cregit-Linux how code gets into the kernel

Release 4.11 mm/vmscan.c

Directory: mm
/*
 *  linux/mm/vmscan.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  Swap reorganised 29.12.95, Stephen Tweedie.
 *  kswapd added: 7.1.96  sct
 *  Removed kswapd_ctl limits, and swap out as many pages as needed
 *  to bring the system back to freepages.high: 2.4.97, Rik van Riel.
 *  Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
 *  Multiqueue VM started 5.8.00, Rik van Riel.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/vmpressure.h>
#include <linux/vmstat.h>
#include <linux/file.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>	/* for try_to_release_page(),
                                        buffer_heads_over_limit */
#include <linux/mm_inline.h>
#include <linux/backing-dev.h>
#include <linux/rmap.h>
#include <linux/topology.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/compaction.h>
#include <linux/notifier.h>
#include <linux/rwsem.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/memcontrol.h>
#include <linux/delayacct.h>
#include <linux/sysctl.h>
#include <linux/oom.h>
#include <linux/prefetch.h>
#include <linux/printk.h>
#include <linux/dax.h>

#include <asm/tlbflush.h>
#include <asm/div64.h>

#include <linux/swapops.h>
#include <linux/balloon_compaction.h>

#include "internal.h"


#define CREATE_TRACE_POINTS
#include <trace/events/vmscan.h>


struct scan_control {
	/* How many pages shrink_list() should reclaim */
	
unsigned long nr_to_reclaim;

	/* This context's GFP mask */
	
gfp_t gfp_mask;

	/* Allocation order */
	
int order;

	/*
         * Nodemask of nodes allowed by the caller. If NULL, all nodes
         * are scanned.
         */
	
nodemask_t	*nodemask;

	/*
         * The memory cgroup that hit its limit and as a result is the
         * primary target of this reclaim invocation.
         */
	
struct mem_cgroup *target_mem_cgroup;

	/* Scan (total_size >> priority) pages at once */
	
int priority;

	/* The highest zone to isolate pages for reclaim from */
	
enum zone_type reclaim_idx;

	/* Writepage batching in laptop mode; RECLAIM_WRITE */
	
unsigned int may_writepage:1;

	/* Can mapped pages be reclaimed? */
	
unsigned int may_unmap:1;

	/* Can pages be swapped as part of reclaim? */
	
unsigned int may_swap:1;

	/* Can cgroups be reclaimed below their normal consumption range? */
	
unsigned int may_thrash:1;

	
unsigned int hibernation_mode:1;

	/* One of the zones is ready for compaction */
	
unsigned int compaction_ready:1;

	/* Incremented by the number of inactive pages that were scanned */
	
unsigned long nr_scanned;

	/* Number of pages freed so far during a call to shrink_zones() */
	
unsigned long nr_reclaimed;
};

#ifdef ARCH_HAS_PREFETCH

#define prefetch_prev_lru_page(_page, _base, _field)			\
	do {                                                            \
                if ((_page)->lru.prev != _base) {                       \
                        struct page *prev;                              \
                                                                        \
                        prev = lru_to_page(&(_page->lru));              \
                        prefetch(&prev->_field);                        \
                }                                                       \
        } while (0)
#else

#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
#endif

#ifdef ARCH_HAS_PREFETCHW

#define prefetchw_prev_lru_page(_page, _base, _field)			\
	do {                                                            \
                if ((_page)->lru.prev != _base) {                       \
                        struct page *prev;                              \
                                                                        \
                        prev = lru_to_page(&(_page->lru));              \
                        prefetchw(&prev->_field);                       \
                }                                                       \
        } while (0)
#else

#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
#endif

/*
 * From 0 .. 100.  Higher means more swappy.
 */

int vm_swappiness = 60;
/*
 * The total number of pages which are beyond the high watermark within all
 * zones.
 */

unsigned long vm_total_pages;

static LIST_HEAD(shrinker_list);
static DECLARE_RWSEM(shrinker_rwsem);

#ifdef CONFIG_MEMCG

static bool global_reclaim(struct scan_control *sc) { return !sc->target_mem_cgroup; }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Weiner17100.00%2100.00%
Total17100.00%2100.00%

/** * sane_reclaim - is the usual dirty throttling mechanism operational? * @sc: scan_control in question * * The normal page dirty throttling mechanism in balance_dirty_pages() is * completely broken with the legacy memcg and direct stalling in * shrink_page_list() is used for throttling instead, which lacks all the * niceties such as fairness, adaptive pausing, bandwidth proportional * allocation and configurability. * * This function tests whether the vmscan currently in progress can assume * that the normal dirty throttling mechanism is operational. */
static bool sane_reclaim(struct scan_control *sc) { struct mem_cgroup *memcg = sc->target_mem_cgroup; if (!memcg) return true; #ifdef CONFIG_CGROUP_WRITEBACK if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return true; #endif return false; }

Contributors

PersonTokensPropCommitsCommitProp
Tejun Heo4291.30%133.33%
Vladimir Davydov24.35%133.33%
Linus Torvalds24.35%133.33%
Total46100.00%3100.00%

#else
static bool global_reclaim(struct scan_control *sc) { return true; }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Weiner14100.00%1100.00%
Total14100.00%1100.00%


static bool sane_reclaim(struct scan_control *sc) { return true; }

Contributors

PersonTokensPropCommitsCommitProp
Tejun Heo14100.00%1100.00%
Total14100.00%1100.00%

#endif /* * This misses isolated pages which are not accounted for to save counters. * As the data only determines if reclaim or compaction continues, it is * not expected that isolated pages will be a dominating factor. */
unsigned long zone_reclaimable_pages(struct zone *zone) { unsigned long nr; nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) + zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE); if (get_nr_swap_pages() > 0) nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) + zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON); return nr; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman57100.00%1100.00%
Total57100.00%1100.00%


unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat) { unsigned long nr; nr = node_page_state_snapshot(pgdat, NR_ACTIVE_FILE) + node_page_state_snapshot(pgdat, NR_INACTIVE_FILE) + node_page_state_snapshot(pgdat, NR_ISOLATED_FILE); if (get_nr_swap_pages() > 0) nr += node_page_state_snapshot(pgdat, NR_ACTIVE_ANON) + node_page_state_snapshot(pgdat, NR_INACTIVE_ANON) + node_page_state_snapshot(pgdat, NR_ISOLATED_ANON); return nr; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman3549.30%133.33%
Lisa Du2636.62%133.33%
Michal Hocko1014.08%133.33%
Total71100.00%3100.00%


bool pgdat_reclaimable(struct pglist_data *pgdat) { return node_page_state_snapshot(pgdat, NR_PAGES_SCANNED) < pgdat_reclaimable_pages(pgdat) * 6; }

Contributors

PersonTokensPropCommitsCommitProp
Lisa Du1456.00%133.33%
Mel Gorman1144.00%266.67%
Total25100.00%3100.00%

/** * lruvec_lru_size - Returns the number of pages on the given LRU list. * @lruvec: lru vector * @lru: lru to use * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list) */
unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx) { unsigned long lru_size; int zid; if (!mem_cgroup_disabled()) lru_size = mem_cgroup_get_lru_size(lruvec, lru); else lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru); for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) { struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid]; unsigned long size; if (!managed_zone(zone)) continue; if (!mem_cgroup_disabled()) size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid); else size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid], NR_ZONE_LRU_BASE + lru); lru_size -= min(size, lru_size); } return lru_size; }

Contributors

PersonTokensPropCommitsCommitProp
Michal Hocko11475.50%220.00%
Motohiro Kosaki2415.89%220.00%
Konstantin Khlebnikov63.97%110.00%
Hugh Dickins31.99%220.00%
Mel Gorman21.32%110.00%
Johannes Weiner10.66%110.00%
Kamezawa Hiroyuki10.66%110.00%
Total151100.00%10100.00%

/* * Add a shrinker callback to be called from the vm. */
int register_shrinker(struct shrinker *shrinker) { size_t size = sizeof(*shrinker->nr_deferred); if (shrinker->flags & SHRINKER_NUMA_AWARE) size *= nr_node_ids; shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); if (!shrinker->nr_deferred) return -ENOMEM; down_write(&shrinker_rwsem); list_add_tail(&shrinker->list, &shrinker_list); up_write(&shrinker_rwsem); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Glauber de Oliveira Costa4251.85%116.67%
Andrew Morton2834.57%116.67%
Nicholas Piggin44.94%116.67%
Konstantin Khlebnikov44.94%116.67%
Rusty Russell22.47%116.67%
Christoph Hellwig11.23%116.67%
Total81100.00%6100.00%

EXPORT_SYMBOL(register_shrinker); /* * Remove one */
void unregister_shrinker(struct shrinker *shrinker) { down_write(&shrinker_rwsem); list_del(&shrinker->list); up_write(&shrinker_rwsem); kfree(shrinker->nr_deferred); }

Contributors

PersonTokensPropCommitsCommitProp
Andrew Morton2567.57%125.00%
Andrey Vagin718.92%125.00%
Nicholas Piggin410.81%125.00%
Rusty Russell12.70%125.00%
Total37100.00%4100.00%

EXPORT_SYMBOL(unregister_shrinker); #define SHRINK_BATCH 128
static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, struct shrinker *shrinker, unsigned long nr_scanned, unsigned long nr_eligible) { unsigned long freed = 0; unsigned long long delta; long total_scan; long freeable; long nr; long new_nr; int nid = shrinkctl->nid; long batch_size = shrinker->batch ? shrinker->batch : SHRINK_BATCH; long scanned = 0, next_deferred; freeable = shrinker->count_objects(shrinker, shrinkctl); if (freeable == 0) return 0; /* * copy the current shrinker scan count into a local variable * and zero it so that other concurrent shrinker invocations * don't also do this scanning work. */ nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); total_scan = nr; delta = (4 * nr_scanned) / shrinker->seeks; delta *= freeable; do_div(delta, nr_eligible + 1); total_scan += delta; if (total_scan < 0) { pr_err("shrink_slab: %pF negative objects to delete nr=%ld\n", shrinker->scan_objects, total_scan); total_scan = freeable; next_deferred = nr; } else next_deferred = total_scan; /* * We need to avoid excessive windup on filesystem shrinkers * due to large numbers of GFP_NOFS allocations causing the * shrinkers to return -1 all the time. This results in a large * nr being built up so when a shrink that can do some work * comes along it empties the entire cache due to nr >>> * freeable. This is bad for sustaining a working set in * memory. * * Hence only allow the shrinker to scan the entire cache when * a large delta change is calculated directly. */ if (delta < freeable / 4) total_scan = min(total_scan, freeable / 2); /* * Avoid risking looping forever due to too large nr value: * never try to free more than twice the estimate number of * freeable entries. */ if (total_scan > freeable * 2) total_scan = freeable * 2; trace_mm_shrink_slab_start(shrinker, shrinkctl, nr, nr_scanned, nr_eligible, freeable, delta, total_scan); /* * Normally, we should not scan less than batch_size objects in one * pass to avoid too frequent shrinker calls, but if the slab has less * than batch_size objects in total and we are really tight on memory, * we will try to reclaim all available objects, otherwise we can end * up failing allocations although there are plenty of reclaimable * objects spread over several slabs with usage less than the * batch_size. * * We detect the "tight on memory" situations by looking at the total * number of objects we want to scan (total_scan). If it is greater * than the total number of objects on slab (freeable), we must be * scanning at high prio and therefore should try to reclaim as much as * possible. */ while (total_scan >= batch_size || total_scan >= freeable) { unsigned long ret; unsigned long nr_to_scan = min(batch_size, total_scan); shrinkctl->nr_to_scan = nr_to_scan; ret = shrinker->scan_objects(shrinker, shrinkctl); if (ret == SHRINK_STOP) break; freed += ret; count_vm_events(SLABS_SCANNED, nr_to_scan); total_scan -= nr_to_scan; scanned += nr_to_scan; cond_resched(); } if (next_deferred >= scanned) next_deferred -= scanned; else next_deferred = 0; /* * move the unused scan count back into the shrinker in a * manner that handles concurrent updates. If we exhausted the * scan, there is no need to do an update. */ if (next_deferred > 0) new_nr = atomic_long_add_return(next_deferred, &shrinker->nr_deferred[nid]); else new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); trace_mm_shrink_slab_end(shrinker, nid, freed, nr, new_nr, total_scan); return freed; }

Contributors

PersonTokensPropCommitsCommitProp
Dave Chinner12032.17%720.00%
Andrew Morton7119.03%1028.57%
Shaohua Li379.92%12.86%
Glauber de Oliveira Costa349.12%12.86%
Vladimir Davydov318.31%38.57%
Konstantin Khlebnikov277.24%25.71%
Andrea Arcangeli184.83%12.86%
Nicholas Piggin133.49%12.86%
Ying Han61.61%25.71%
Johannes Weiner61.61%12.86%
Dave Hansen41.07%25.71%
Christoph Lameter20.54%12.86%
David Rientjes20.54%12.86%
Pintu Kumar10.27%12.86%
Bernardo Innocenti10.27%12.86%
Total373100.00%35100.00%

/** * shrink_slab - shrink slab caches * @gfp_mask: allocation context * @nid: node whose slab caches to target * @memcg: memory cgroup whose slab caches to target * @nr_scanned: pressure numerator * @nr_eligible: pressure denominator * * Call the shrink functions to age shrinkable caches. * * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set, * unaware shrinkers will receive a node id of 0 instead. * * @memcg specifies the memory cgroup to target. If it is not NULL, * only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan * objects from the memory cgroup specified. Otherwise, only unaware * shrinkers are called. * * @nr_scanned and @nr_eligible form a ratio that indicate how much of * the available objects should be scanned. Page reclaim for example * passes the number of pages scanned and the number of pages on the * LRU lists that it considered on @nid, plus a bias in @nr_scanned * when it encountered mapped pages. The ratio is further biased by * the ->seeks setting of the shrink function, which indicates the * cost to recreate an object relative to that of an LRU page. * * Returns the number of reclaimed slab objects. */
static unsigned long shrink_slab(gfp_t gfp_mask, int nid, struct mem_cgroup *memcg, unsigned long nr_scanned, unsigned long nr_eligible) { struct shrinker *shrinker; unsigned long freed = 0; if (memcg && (!memcg_kmem_enabled() || !mem_cgroup_online(memcg))) return 0; if (nr_scanned == 0) nr_scanned = SWAP_CLUSTER_MAX; if (!down_read_trylock(&shrinker_rwsem)) { /* * If we would return 0, our callers would understand that we * have nothing else to shrink and give up trying. By returning * 1 we keep it going and assume we'll be able to shrink next * time. */ freed = 1; goto out; } list_for_each_entry(shrinker, &shrinker_list, list) { struct shrink_control sc = { .gfp_mask = gfp_mask, .nid = nid, .memcg = memcg, }; /* * If kernel memory accounting is disabled, we ignore * SHRINKER_MEMCG_AWARE flag and call all shrinkers * passing NULL for memcg. */ if (memcg_kmem_enabled() && !!memcg != !!(shrinker->flags & SHRINKER_MEMCG_AWARE)) continue; if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) sc.nid = 0; freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible); } up_read(&shrinker_rwsem); out: cond_resched(); return freed; }

Contributors

PersonTokensPropCommitsCommitProp
Vladimir Davydov7038.46%333.33%
Glauber de Oliveira Costa6636.26%111.11%
Johannes Weiner3117.03%111.11%
Andrew Morton73.85%111.11%
MinChan Kim52.75%111.11%
Nicholas Piggin21.10%111.11%
Dave Chinner10.55%111.11%
Total182100.00%9100.00%


void drop_slab_node(int nid) { unsigned long freed; do { struct mem_cgroup *memcg = NULL; freed = 0; do { freed += shrink_slab(GFP_KERNEL, nid, memcg, 1000, 1000); } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); } while (freed > 10); }

Contributors

PersonTokensPropCommitsCommitProp
Vladimir Davydov69100.00%1100.00%
Total69100.00%1100.00%


void drop_slab(void) { int nid; for_each_online_node(nid) drop_slab_node(nid); }

Contributors

PersonTokensPropCommitsCommitProp
Vladimir Davydov19100.00%1100.00%
Total19100.00%1100.00%


static inline int is_page_cache_freeable(struct page *page) { /* * A freeable page cache page is referenced only by the caller * that isolated the page, the page cache radix tree and * optional buffer heads at page->private. */ return page_count(page) - page_has_private(page) == 2; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew Morton2284.62%125.00%
Linus Torvalds27.69%125.00%
Johannes Weiner13.85%125.00%
David Howells13.85%125.00%
Total26100.00%4100.00%


static int may_write_to_inode(struct inode *inode, struct scan_control *sc) { if (current->flags & PF_SWAPWRITE) return 1; if (!inode_write_congested(inode)) return 1; if (inode_to_bdi(inode) == current->backing_dev_info) return 1; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew Morton3665.45%125.00%
Tejun Heo916.36%125.00%
Motohiro Kosaki59.09%125.00%
Christoph Lameter59.09%125.00%
Total55100.00%4100.00%

/* * We detected a synchronous write error writing a page out. Probably * -ENOSPC. We need to propagate that into the address_space for a subsequent * fsync(), msync() or close(). * * The tricky part is that after writepage we cannot touch the mapping: nothing * prevents it from being freed up. But we have a ref on the page and once * that page is locked, the mapping is pinned. * * We're allowed to run sleeping lock_page() here because we know the caller has * __GFP_FS. */
static void handle_write_error(struct address_space *mapping, struct page *page, int error) { lock_page(page); if (page_mapping(page) == mapping) mapping_set_error(mapping, error); unlock_page(page); }

Contributors

PersonTokensPropCommitsCommitProp
Andrew Morton4293.33%360.00%
Guillaume Chazarain24.44%120.00%
Jens Axboe12.22%120.00%
Total45100.00%5100.00%

/* possible outcome of pageout() */ typedef enum { /* failed to write page out, page is locked */ PAGE_KEEP, /* move page to the active list, page is locked */ PAGE_ACTIVATE, /* page has been sent to the disk successfully, page is unlocked */ PAGE_SUCCESS, /* page is clean and locked */ PAGE_CLEAN, } pageout_t; /* * pageout is called by shrink_page_list() for each dirty page. * Calls ->writepage(). */
static pageout_t pageout(struct page *page, struct address_space *mapping, struct scan_control *sc) { /* * If the page is dirty, only perform writeback if that write * will be non-blocking. To prevent this allocation from being * stalled by pagecache activity. But note that there may be * stalls if we need to run get_block(). We could test * PagePrivate for that. * * If this process is currently in __generic_file_write_iter() against * this page's queue, we can perform writeback even if that * will block. * * If the page is swapcache, write it back even if that would * block, for some throttling. This happens by accident, because * swap_backing_dev_info is bust: it doesn't reflect the * congestion state of the swapdevs. Easy to fix, if needed. */ if (!is_page_cache_freeable(page)) return PAGE_KEEP; if (!mapping) { /* * Some data journaling orphaned pages can have * page->mapping == NULL while being dirty with clean buffers. */ if (page_has_private(page)) { if (try_to_free_buffers(page)) { ClearPageDirty(page); pr_info("%s: orphaned page\n", __func__); return PAGE_CLEAN; } } return PAGE_KEEP; } if (mapping->a_ops->writepage == NULL) return PAGE_ACTIVATE; if (!may_write_to_inode(mapping->host, sc)) return PAGE_KEEP; if (clear_page_dirty_for_io(page)) { int res; struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, .nr_to_write = SWAP_CLUSTER_MAX, .range_start = 0, .range_end = LLONG_MAX, .for_reclaim = 1, }; SetPageReclaim(page); res = mapping->a_ops->writepage(page, &wbc); if (res < 0) handle_write_error(mapping, page, res); if (res == AOP_WRITEPAGE_ACTIVATE) { ClearPageReclaim(page); return PAGE_ACTIVATE; } if (!PageWriteback(page)) { /* synchronous write or broken a_ops? */ ClearPageReclaim(page); } trace_mm_vmscan_writepage(page); inc_node_page_state(page, NR_VMSCAN_WRITE); return PAGE_SUCCESS; } return PAGE_CLEAN; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew Morton16771.98%212.50%
Andrea Arcangeli3314.22%16.25%
Hirofumi Ogawa104.31%16.25%
Motohiro Kosaki62.59%16.25%
Mel Gorman62.59%212.50%
Christoph Hellwig20.86%16.25%
Harvey Harrison10.43%16.25%
Tejun Heo10.43%16.25%
Christoph Lameter10.43%16.25%
Zach Brown10.43%16.25%
Mitchel Humpherys10.43%16.25%
David Howells10.43%16.25%
Andy Whitcroft10.43%16.25%
Al Viro10.43%16.25%
Total232100.00%16100.00%

/* * Same as remove_mapping, but if the page is removed from the mapping, it * gets returned with a refcount of 0. */
static int __remove_mapping(struct address_space *mapping, struct page *page, bool reclaimed) { unsigned long flags; BUG_ON(!PageLocked(page)); BUG_ON(mapping != page_mapping(page)); spin_lock_irqsave(&mapping->tree_lock, flags); /* * The non racy check for a busy page. * * Must be careful with the order of the tests. When someone has * a ref to the page, it may be possible that they dirty it then * drop the reference. So if PageDirty is tested before page_count * here, then the following race may occur: * * get_user_pages(&page); * [user mapping goes away] * write_to(page); * !PageDirty(page) [good] * SetPageDirty(page); * put_page(page); * !page_count(page) [good, discard it] * * [oops, our write_to data is lost] * * Reversing the order of the tests ensures such a situation cannot * escape unnoticed. The smp_rmb is needed to ensure the page->flags * load is not satisfied before that of page->_refcount. * * Note that if SetPageDirty is always performed via set_page_dirty, * and thus under tree_lock, then this ordering is not required. */ if (!page_ref_freeze(page, 2)) goto cannot_free; /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ if (unlikely(PageDirty(page))) { page_ref_unfreeze(page, 2); goto cannot_free; } if (PageSwapCache(page)) { swp_entry_t swap = { .val = page_private(page) }; mem_cgroup_swapout(page, swap); __delete_from_swap_cache(page); spin_unlock_irqrestore(&mapping->tree_lock, flags); swapcache_free(swap); } else { void (*freepage)(struct page *); void *shadow = NULL; freepage = mapping->a_ops->freepage; /* * Remember a shadow entry for reclaimed file cache in * order to detect refaults, thus thrashing, later on. * * But don't store shadows in an address space that is * already exiting. This is not just an optizimation, * inode reclaim needs to empty out the radix tree or * the nodes are lost. Don't plant shadows behind its * back. * * We also don't store shadows for DAX mappings because the * only page cache pages found in these are zero pages * covering holes, and because we don't want to mix DAX * exceptional entries and shadow exceptional entries in the * same page_tree. */ if (reclaimed && page_is_file_cache(page) && !mapping_exiting(mapping) && !dax_mapping(mapping)) shadow = workingset_eviction(mapping, page); __delete_from_page_cache(page, shadow); spin_unlock_irqrestore(&mapping->tree_lock, flags); if (freepage != NULL) freepage(page); } return 1; cannot_free: spin_unlock_irqrestore(&mapping->tree_lock, flags); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Christoph Lameter10442.80%17.69%
Johannes Weiner4217.28%323.08%
Nicholas Piggin3313.58%215.38%
Linus Torvalds3012.35%17.69%
Greg Thelen229.05%17.69%
Ross Zwisler72.88%17.69%
JoonSoo Kim31.23%215.38%
Kamezawa Hiroyuki10.41%17.69%
MinChan Kim10.41%17.69%
Total243100.00%13100.00%

/* * Attempt to detach a locked page from its ->mapping. If it is dirty or if * someone else has a ref on the page, abort and return 0. If it was * successfully detached, return 1. Assumes the caller has a single ref on * this page. */
int remove_mapping(struct address_space *mapping, struct page *page) { if (__remove_mapping(mapping, page, false)) { /* * Unfreezing the refcount with 1 rather than 2 effectively * drops the pagecache ref for us without requiring another * atomic operation. */ page_ref_unfreeze(page, 1); return 1; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Nicholas Piggin3992.86%133.33%
Johannes Weiner24.76%133.33%
JoonSoo Kim12.38%133.33%
Total42100.00%3100.00%

/** * putback_lru_page - put previously isolated page onto appropriate LRU list * @page: page to be put back to appropriate lru list * * Add previously isolated @page to appropriate LRU list. * Page may still be unevictable for other reasons. * * lru_lock must not be held, interrupts must be enabled. */
void putback_lru_page(struct page *page) { bool is_unevictable; int was_unevictable = PageUnevictable(page); VM_BUG_ON_PAGE(PageLRU(page), page); redo: ClearPageUnevictable(page); if (page_evictable(page)) { /* * For evictable pages, we can use the cache. * In event of a race, worst case is we end up with an * unevictable page on [in]active list. * We know how to handle that. */ is_unevictable = false; lru_cache_add(page); } else { /* * Put unevictable pages directly on zone's unevictable * list. */ is_unevictable = true; add_page_to_unevictable_list(page); /* * When racing with an mlock or AS_UNEVICTABLE clearing * (page is unlocked) make sure that if the other thread * does not observe our setting of PG_lru and fails * isolation/check_move_unevictable_pages, * we see PG_mlocked/AS_UNEVICTABLE cleared below and move * the page back to the evictable list. * * The other side is TestClearPageMlocked() or shmem_lock(). */ smp_mb(); } /* * page's status can change while we move it among lru. If an evictable * page is on unevictable list, it never be freed. To avoid that, * check after we added it to the list, again. */ if (is_unevictable && page_evictable(page)) { if (!isolate_lru_page(page)) { put_page(page); goto redo; } /* This means someone else dropped this page from LRU * So, it will be freed or putback to LRU again. There is * nothing to do here. */ } if (was_unevictable && !is_unevictable) count_vm_event(UNEVICTABLE_PGRESCUED); else if (!was_unevictable && is_unevictable) count_vm_event(UNEVICTABLE_PGCULLED); put_page(page); /* drop ref from isolate */ }

Contributors

PersonTokensPropCommitsCommitProp
Lee Schermerhorn11886.76%228.57%
Vlastimil Babka107.35%114.29%
Sasha Levin32.21%114.29%
Johannes Weiner32.21%114.29%
Hugh Dickins10.74%114.29%
Mel Gorman10.74%114.29%
Total136100.00%7100.00%

enum page_references { PAGEREF_RECLAIM, PAGEREF_RECLAIM_CLEAN, PAGEREF_KEEP, PAGEREF_ACTIVATE, };
static enum page_references page_check_references(struct page *page, struct scan_control *sc) { int referenced_ptes, referenced_page; unsigned long vm_flags; referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup, &vm_flags); referenced_page = TestClearPageReferenced(page); /* * Mlock lost the isolation race with us. Let try_to_unmap() * move the page to the unevictable list. */ if (vm_flags & VM_LOCKED) return PAGEREF_RECLAIM; if (referenced_ptes) { if (PageSwapBacked(page)) return PAGEREF_ACTIVATE; /* * All mapped pages start out with page table * references from the instantiating fault, so we need * to look twice if a mapped file page is used more * than once. * * Mark it and spare it for another trip around the * inactive list. Another page table reference will * lead to its activation. * * Note: the mark is set for activated pages as well * so that recently deactivated but used pages are * quickly recovered. */ SetPageReferenced(page); if (referenced_page || referenced_ptes > 1) return PAGEREF_ACTIVATE; /* * Activate file-backed executable pages after first usage. */ if (vm_flags & VM_EXEC) return PAGEREF_ACTIVATE; return PAGEREF_KEEP; } /* Reclaim if clean, defer dirty pages to writeback */ if (referenced_page && !PageSwapBacked(page)) return PAGEREF_RECLAIM_CLEAN; return PAGEREF_RECLAIM; }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Weiner10182.79%342.86%
Konstantin Khlebnikov1411.48%228.57%
Motohiro Kosaki64.92%114.29%
Michal Hocko10.82%114.29%
Total122100.00%7100.00%

/* Check if a page is dirty or under writeback */
static void page_check_dirty_writeback(struct page *page, bool *dirty, bool *writeback) { struct address_space *mapping; /* * Anonymous pages are not handled by flushers and must be written * from reclaim context. Do not stall reclaim based on them */ if (!page_is_file_cache(page)) { *dirty = false; *writeback = false; return; } /* By default assume that the page flags are accurate */ *dirty = PageDirty(page); *writeback = PageWriteback(page); /* Verify dirty/writeback state if the filesystem supports it */ if (!page_has_private(page)) return; mapping = page_mapping(page); if (mapping && mapping->a_ops->is_dirty_writeback) mapping->a_ops->is_dirty_writeback(page, dirty, writeback); }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman103100.00%2100.00%
Total103100.00%2100.00%

struct reclaim_stat { unsigned nr_dirty; unsigned nr_unqueued_dirty; unsigned nr_congested; unsigned nr_writeback; unsigned nr_immediate; unsigned nr_activate; unsigned nr_ref_keep; unsigned nr_unmap_fail; }; /* * shrink_page_list() returns the number of reclaimed pages */
static unsigned long shrink_page_list(struct list_head *page_list, struct pglist_data *pgdat, struct scan_control *sc, enum ttu_flags ttu_flags, struct reclaim_stat *stat, bool force_reclaim) { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); int pgactivate = 0; unsigned nr_unqueued_dirty = 0; unsigned nr_dirty = 0; unsigned nr_congested = 0; unsigned nr_reclaimed = 0; unsigned nr_writeback = 0; unsigned nr_immediate = 0; unsigned nr_ref_keep = 0; unsigned nr_unmap_fail = 0; cond_resched(); while (!list_empty(page_list)) { struct address_space *mapping; struct page *page; int may_enter_fs; enum page_references references = PAGEREF_RECLAIM_CLEAN; bool dirty, writeback; bool lazyfree = false; int ret = SWAP_SUCCESS; cond_resched(); page = lru_to_page(page_list); list_del(&page->lru); if (!trylock_page(page)) goto keep; VM_BUG_ON_PAGE(PageActive(page), page); sc->nr_scanned++; if (unlikely(!page_evictable(page))) goto cull_mlocked; if (!sc->may_unmap && page_mapped(page)) goto keep_locked; /* Double the slab pressure for mapped and swapcache pages */ if (page_mapped(page) || PageSwapCache(page)) sc->nr_scanned++; may_enter_fs = (sc->gfp_mask & __GFP_FS) || (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); /* * The number of dirty pages determines if a zone is marked * reclaim_congested which affects wait_iff_congested. kswapd * will stall and start writing pages if the tail of the LRU * is all dirty unqueued pages. */ page_check_dirty_writeback(page, &dirty, &writeback); if (dirty || writeback) nr_dirty++; if (dirty && !writeback) nr_unqueued_dirty++; /* * Treat this page as congested if the underlying BDI is or if * pages are cycling through the LRU so quickly that the * pages marked for immediate reclaim are making it to the * end of the LRU a second time. */ mapping = page_mapping(page); if (((dirty || writeback) && mapping && inode_write_congested(mapping->host)) || (writeback && PageReclaim(page))) nr_congested++; /* * If a page at the tail of the LRU is under writeback, there * are three cases to consider. * * 1) If reclaim is encountering an excessive number of pages * under writeback and this page is both under writeback and * PageReclaim then it indicates that pages are being queued * for IO but are being recycled through the LRU before the * IO can complete. Waiting on the page itself risks an * indefinite stall if it is impossible to writeback the * page due to IO error or disconnected storage so instead * note that the LRU is being scanned too quickly and the * caller can stall after page list has been processed. * * 2) Global or new memcg reclaim encounters a page that is * not marked for immediate reclaim, or the caller does not * have __GFP_FS (or __GFP_IO if it's simply going to swap, * not to fs). In this case mark the page for immediate * reclaim and continue scanning. * * Require may_enter_fs because we would wait on fs, which * may not have submitted IO yet. And the loop driver might * enter reclaim, and deadlock if it waits on a page for * which it is needed to do the write (loop masks off * __GFP_IO|__GFP_FS for this reason); but more thought * would probably show more reasons. * * 3) Legacy memcg encounters a page that is already marked * PageReclaim. memcg does not have any dirty pages * throttling so we could easily OOM just because too many * pages are in writeback and there is nothing else to * reclaim. Wait for the writeback to complete. * * In cases 1) and 2) we activate the pages to get them out of * the way while we continue scanning for clean pages on the * inactive list and refilling from the active list. The * observation here is that waiting for disk writes is more * expensive than potentially causing reloads down the line. * Since they're marked for immediate reclaim, they won't put * memory pressure on the cache working set any longer than it * takes to write them to disk. */ if (PageWriteback(page)) { /* Case 1 above */ if (current_is_kswapd() && PageReclaim(page) && test_bit(PGDAT_WRITEBACK, &pgdat->flags)) { nr_immediate++; goto activate_locked; /* Case 2 above */ } else if (sane_reclaim(sc) || !PageReclaim(page) || !may_enter_fs) { /* * This is slightly racy - end_page_writeback() * might have just cleared PageReclaim, then * setting PageReclaim here end up interpreted * as PageReadahead - but that does not matter * enough to care. What we do want is for this * page to have PageReclaim set next time memcg * reclaim reaches the tests above, so it will * then wait_on_page_writeback() to avoid OOM; * and it's also appropriate in global reclaim. */ SetPageReclaim(page); nr_writeback++; goto activate_locked; /* Case 3 above */ } else { unlock_page(page); wait_on_page_writeback(page); /* then go back and try same page again */ list_add_tail(&page->lru, page_list); continue; } } if (!force_reclaim) references = page_check_references(page, sc); switch (references) { case PAGEREF_ACTIVATE: goto activate_locked; case PAGEREF_KEEP: nr_ref_keep++; goto keep_locked; case PAGEREF_RECLAIM: case PAGEREF_RECLAIM_CLEAN: ; /* try to reclaim the page below */ } /* * Anonymous process memory has backing store? * Try to allocate it some swap space here. */ if (PageAnon(page) && !PageSwapCache(page)) { if (!(sc->gfp_mask & __GFP_IO)) goto keep_locked; if (!add_to_swap(page, page_list)) goto activate_locked; lazyfree = true; may_enter_fs = 1; /* Adding to swap updated mapping */ mapping = page_mapping(page); } else if (unlikely(PageTransHuge(page))) { /* Split file THP */ if (split_huge_page_to_list(page, page_list)) goto keep_locked; } VM_BUG_ON_PAGE(PageTransHuge(page), page); /* * The page is mapped into the page tables of one or more * processes. Try to unmap it here. */ if (page_mapped(page) && mapping) { switch (ret = try_to_unmap(page, lazyfree ? (ttu_flags | TTU_BATCH_FLUSH | TTU_LZFREE) : (ttu_flags | TTU_BATCH_FLUSH))) { case SWAP_FAIL: nr_unmap_fail++; goto activate_locked; case SWAP_AGAIN: goto keep_locked; case SWAP_MLOCK: goto cull_mlocked; case SWAP_LZFREE: goto lazyfree; case SWAP_SUCCESS: ; /* try to free the page below */ } } if (PageDirty(page)) { /* * Only kswapd can writeback filesystem pages * to avoid risk of stack overflow. But avoid * injecting inefficient single-page IO into * flusher writeback as much as possible: only * write pages when we've encountered many * dirty pages, and when we've already scanned * the rest of the LRU for clean pages and see * the same dirty pages again (PageReclaim). */ if (page_is_file_cache(page) && (!current_is_kswapd() || !PageReclaim(page) || !test_bit(PGDAT_DIRTY, &pgdat->flags))) { /* * Immediately reclaim when written back. * Similar in principal to deactivate_page() * except we already have the page isolated * and know it's dirty */ inc_node_page_state(page, NR_VMSCAN_IMMEDIATE); SetPageReclaim(page); goto activate_locked; } if (references == PAGEREF_RECLAIM_CLEAN) goto keep_locked; if (!may_enter_fs) goto keep_locked; if (!sc->may_writepage) goto keep_locked; /* * Page is dirty. Flush the TLB if a writable entry * potentially exists to avoid CPU writes after IO * starts and then write it out here. */ try_to_unmap_flush_dirty(); switch (pageout(page, mapping, sc)) { case PAGE_KEEP: goto keep_locked; case PAGE_ACTIVATE: goto activate_locked; case PAGE_SUCCESS: if (PageWriteback(page)) goto keep; if (PageDirty(page)) goto keep; /* * A synchronous write - probably a ramdisk. Go * ahead and try to reclaim the page. */ if (!trylock_page(page)) goto keep; if (PageDirty(page) || PageWriteback(page)) goto keep_locked; mapping = page_mapping(page); case PAGE_CLEAN: ; /* try to free the page below */ } } /* * If the page has buffers, try to free the buffer mappings * associated with this page. If we succeed we try to free * the page as well. * * We do this even if the page is PageDirty(). * try_to_release_page() does not perform I/O, but it is * possible for a page to have PageDirty set, but it is actually * clean (all its buffers are clean). This happens if the * buffers were written out directly, with submit_bh(). ext3 * will do this, as well as the blockdev mapping. * try_to_release_page() will discover that cleanness and will * drop the buffers and mark the page clean - it can be freed. * * Rarely, pages can have buffers and no ->mapping. These are * the pages which were not successfully invalidated in * truncate_complete_page(). We try to drop those buffers here * and if that worked, and the page is no longer mapped into * process address space (page_count == 1) it can be freed. * Otherwise, leave the page on the LRU so it is swappable. */ if (page_has_private(page)) { if (!try_to_release_page(page, sc->gfp_mask)) goto activate_locked; if (!mapping && page_count(page) == 1) { unlock_page(page); if (put_page_testzero(page)) goto free_it; else { /* * rare race with speculative reference. * the speculative reference will free * this page shortly, so we may * increment nr_reclaimed here (and * leave it off the LRU). */ nr_reclaimed++; continue; } } } lazyfree: if (!mapping || !__remove_mapping(mapping, page, true)) goto keep_locked; /* * At this point, we have no other references and there is * no way to pick any more up (removed from LRU, removed * from pagecache). Can use non-atomic bitops now (and * we obviously don't have to worry about waking up a process * waiting on the page lock, because there are no references. */ __ClearPageLocked(page); free_it: if (ret == SWAP_LZFREE) count_vm_event(PGLAZYFREED); nr_reclaimed++; /* * Is there need to periodically free_page_list? It would * appear not as the counts should be low */ list_add(&page->lru, &free_pages); continue; cull_mlocked: if (PageSwapCache(page)) try_to_free_swap(page); unlock_page(page); list_add(&page->lru, &ret_pages); continue; activate_locked: /* Not a candidate for swapping, so reclaim swap space. */ if (PageSwapCache(page) && mem_cgroup_swap_full(page)) try_to_free_swap(page); VM_BUG_ON_PAGE(PageActive(page), page); SetPageActive(page); pgactivate++; keep_locked: unlock_page(page); keep: list_add(&page->lru, &ret_pages); VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page); } mem_cgroup_uncharge_list(&free_pages); try_to_unmap_flush(); free_hot_cold_page_list(&free_pages, true); list_splice(&ret_pages, page_list); count_vm_events(PGACTIVATE, pgactivate); if (stat) { stat->nr_dirty = nr_dirty; stat->nr_congested = nr_congested; stat->nr_unqueued_dirty = nr_unqueued_dirty; stat->nr_writeback = nr_writeback; stat->nr_immediate = nr_immediate; stat->nr_activate = pgactivate; stat->nr_ref_keep = nr_ref_keep; stat->nr_unmap_fail = nr_unmap_fail; } return nr_reclaimed; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew Morton29426.39%2925.89%
Mel Gorman20518.40%1816.07%
Michal Hocko797.09%43.57%
MinChan Kim655.83%21.79%
Hugh Dickins635.66%76.25%
Nicholas Piggin635.66%54.46%
Johannes Weiner565.03%98.04%
Christoph Lameter565.03%54.46%
Linus Torvalds524.67%98.04%
Kirill A. Shutemov373.32%21.79%
Andy Whitcroft272.42%10.89%
Rik Van Riel221.97%32.68%
Linus Torvalds (pre-git)211.89%21.79%
Lee Schermerhorn201.80%21.79%
Motohiro Kosaki100.90%10.89%
Sasha Levin90.81%10.89%
Jaewon Kim70.63%10.89%
Christoph Hellwig70.63%21.79%
Jamie Liu60.54%10.89%
Vladimir Davydov40.36%10.89%
Ingo Molnar30.27%10.89%
Konstantin Khlebnikov20.18%10.89%
Tejun Heo20.18%21.79%
Shaohua Li20.18%10.89%
David Howells10.09%10.89%
Balbir Singh10.09%10.89%
Total1114100.00%112100.00%


unsigned long reclaim_clean_pages_from_list(struct zone *zone, struct list_head *page_list) { struct scan_control sc = { .gfp_mask = GFP_KERNEL, .priority = DEF_PRIORITY, .may_unmap = 1, }; unsigned long ret; struct page *page, *next; LIST_HEAD(clean_pages); list_for_each_entry_safe(page, next, page_list, lru) { if (page_is_file_cache(page) && !PageDirty(page) && !__PageMovable(page)) { ClearPageActive(page); list_move(&page->lru, &clean_pages); } } ret = shrink_page_list(&clean_pages, zone->zone_pgdat, &sc, TTU_UNMAP|TTU_IGNORE_ACCESS, NULL, true); list_splice(&clean_pages, page_list); mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -ret); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
MinChan Kim13791.95%233.33%
Mel Gorman64.03%233.33%
Rafael Aquini53.36%116.67%
Michal Hocko10.67%116.67%
Total149100.00%6100.00%

/* * Attempt to remove the specified page from its LRU. Only take this page * if it is of the appropriate PageActive status. Pages which are being * freed elsewhere are also ignored. * * page: page to consider * mode: one of the LRU isolation modes defined above * * returns 0 on success, -ve errno on failure. */
int __isolate_lru_page(struct page *page, isolate_mode_t mode) { int ret = -EINVAL; /* Only take pages on the LRU. */ if (!PageLRU(page)) return ret; /* Compaction should not handle unevictable pages but CMA can do so */ if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE)) return ret; ret = -EBUSY; /* * To minimise LRU disruption, the caller can indicate that it only * wants to isolate pages it will be able to operate on without * blocking - clean pages for the most part. * * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages * that it is possible to migrate without blocking */ if (mode & ISOLATE_ASYNC_MIGRATE) { /* All the caller can do on PageWriteback is block */ if (PageWriteback(page)) return ret; if (PageDirty(page)) { struct address_space *mapping; /* * Only pages without mappings or that have a * ->migratepage callback are possible to migrate * without blocking */ mapping = page_mapping(page); if (mapping && !mapping->a_ops->migratepage) return ret; } } if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) return ret; if (likely(get_page_unless_zero(page))) { /* * Be careful not to clear PageLRU until after we're * sure the page is not being freed elsewhere -- the * page release code relies on it. */ ClearPageLRU(page); ret = 0; } return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Andy Whitcroft6039.74%112.50%
MinChan Kim4026.49%450.00%
Mel Gorman4026.49%112.50%
Lee Schermerhorn106.62%112.50%
Johannes Weiner10.66%112.50%
Total151100.00%8100.00%

/* * Update LRU sizes after isolating pages. The LRU size updates must * be complete before mem_cgroup_update_lru_size due to a santity check. */
static __always_inline void update_lru_sizes(struct lruvec *lruvec, enum lru_list lru, unsigned long *nr_zone_taken) { int zid; for (zid = 0; zid < MAX_NR_ZONES; zid++) { if (!nr_zone_taken[zid]) continue; __update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); #ifdef CONFIG_MEMCG mem_cgroup_update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]); #endif } }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman7691.57%150.00%
Michal Hocko78.43%150.00%
Total83100.00%2100.00%

/* * zone_lru_lock is heavily contended. Some of the functions that * shrink the lists perform better by taking out a batch of pages * and working on them outside the LRU lock. * * For pagecache intensive workloads, this function is the hottest * spot in the kernel (apart from copy_*_user functions). * * Appropriate locks must be held before calling this function. * * @nr_to_scan: The number of pages to look through on the list. * @lruvec: The LRU vector to pull pages from. * @dst: The temp list to put pages on to. * @nr_scanned: The number of pages that were scanned. * @sc: The scan_control struct for this reclaim session * @mode: One of the LRU isolation modes * @lru: LRU list id for isolating * * returns how many pages were moved onto *@dst. */
static unsigned long isolate_lru_pages(unsigned long nr_to_scan, struct lruvec *lruvec, struct list_head *dst, unsigned long *nr_scanned, struct scan_control *sc, isolate_mode_t mode, enum lru_list lru) { struct list_head *src = &lruvec->lists[lru]; unsigned long nr_taken = 0; unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 }; unsigned long nr_skipped[MAX_NR_ZONES] = { 0, }; unsigned long skipped = 0, total_skipped = 0; unsigned long scan, nr_pages; LIST_HEAD(pages_skipped); for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan && !list_empty(src);) { struct page *page; page = lru_to_page(src); prefetchw_prev_lru_page(page, src, flags); VM_BUG_ON_PAGE(!PageLRU(page), page); if (page_zonenum(page) > sc->reclaim_idx) { list_move(&page->lru, &pages_skipped); nr_skipped[page_zonenum(page)]++; continue; } /* * Account for scanned and skipped separetly to avoid the pgdat * being prematurely marked unreclaimable by pgdat_reclaimable. */ scan++; switch (__isolate_lru_page(page, mode)) { case 0: nr_pages = hpage_nr_pages(page); nr_taken += nr_pages; nr_zone_taken[page_zonenum(page)] += nr_pages; list_move(&page->lru, dst); break; case -EBUSY: /* else it is being freed elsewhere */ list_move(&page->lru, src); continue; default: BUG(); } } /* * Splice any skipped pages to the start of the LRU list. Note that * this disrupts the LRU order when reclaiming for lower zones but * we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX * scanning would soon rescan the same pages to skip and put the * system at risk of premature OOM. */ if (!list_empty(&pages_skipped)) { int zid; for (zid = 0; zid < MAX_NR_ZONES; zid++) { if (!nr_skipped[zid]) continue; __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]); skipped += nr_skipped[zid]; } /* * Account skipped pages as a partial scan as the pgdat may be * close to unreclaimable. If the LRU list is empty, account * skipped pages as a full scan. */ total_skipped = list_empty(src) ? skipped : skipped >> 2; list_splice(&pages_skipped, src); } *nr_scanned = scan + total_skipped; trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, scan, skipped, nr_taken, mode, lru); update_lru_sizes(lruvec, lru, nr_zone_taken); return nr_taken; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman18348.03%725.93%
Christoph Lameter6316.54%13.70%
Andy Whitcroft4211.02%13.70%
Hugh Dickins215.51%414.81%
Michal Hocko194.99%13.70%
Nicholas Piggin123.15%27.41%
Andrew Morton102.62%13.70%
Fengguang Wu82.10%13.70%
Rik Van Riel71.84%27.41%
Konstantin Khlebnikov51.31%27.41%
Vladimir Davydov41.05%13.70%
Sasha Levin30.79%13.70%
Johannes Weiner20.52%13.70%
Tao Ma10.26%13.70%
MinChan Kim10.26%13.70%
Total381100.00%27100.00%

/** * isolate_lru_page - tries to isolate a page from its LRU list * @page: page to isolate from its LRU list * * Isolates a @page from an LRU list, clears PageLRU and adjusts the * vmstat statistic corresponding to whatever LRU list the page was on. * * Returns 0 if the page was removed from an LRU list. * Returns -EBUSY if the page was not on an LRU list. * * The returned page will have PageLRU() cleared. If it was found on * the active list, it will have PageActive set. If it was found on * the unevictable list, it will have the PageUnevictable bit set. That flag * may need to be cleared by the caller before letting the page go. * * The vmstat statistic corresponding to the list on which the page was * found will be decremented. * * Restrictions: * (1) Must be called with an elevated refcount on the page. This is a * fundamentnal difference from isolate_lru_pages (which is called * without a stable reference). * (2) the lru_lock must not be held. * (3) interrupts must be enabled. */
int isolate_lru_page(struct page *page) { int ret = -EBUSY; VM_BUG_ON_PAGE(!page_count(page), page); WARN_RATELIMIT(PageTail(page), "trying to isolate tail page"); if (PageLRU(page)) { struct zone *zone = page_zone(page); struct lruvec *lruvec; spin_lock_irq(zone_lru_lock(zone)); lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat); if (PageLRU(page)) { int lru = page_lru(page); get_page(page); ClearPageLRU(page); del_page_from_lru_list(page, lruvec, lru); ret = 0; } spin_unlock_irq(zone_lru_lock(zone)); } return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Nicholas Piggin6650.38%110.00%
Hugh Dickins2015.27%110.00%
Konstantin Khlebnikov139.92%110.00%
Kirill A. Shutemov107.63%220.00%
Mel Gorman86.11%220.00%
Rik Van Riel75.34%110.00%
Lee Schermerhorn43.05%110.00%
Sasha Levin32.29%110.00%
Total131100.00%10100.00%

/* * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and * then get resheduled. When there are massive number of tasks doing page * allocation, such sleeping direct reclaimers may keep piling up on each CPU, * the LRU list will go small and be scanned faster than necessary, leading to * unnecessary swapping, thrashing and OOM. */
static int too_many_isolated(struct pglist_data *pgdat, int file, struct scan_control *sc) { unsigned long inactive, isolated; if (current_is_kswapd()) return 0; if (!sane_reclaim(sc)) return 0; if (file) { inactive = node_page_state(pgdat, NR_INACTIVE_FILE); isolated = node_page_state(pgdat, NR_ISOLATED_FILE); } else { inactive = node_page_state(pgdat, NR_INACTIVE_ANON); isolated = node_page_state(pgdat, NR_ISOLATED_ANON); } /* * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they * won't get blocked by normal direct-reclaimers, forming a circular * deadlock. */ if ((sc->gfp_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS)) inactive >>= 3; return isolated > inactive; }

Contributors

PersonTokensPropCommitsCommitProp
Rik Van Riel8369.75%120.00%
Mel Gorman2016.81%240.00%
Fengguang Wu1512.61%120.00%
Tejun Heo10.84%120.00%
Total119100.00%5100.00%


static noinline_for_stack void putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) { struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; struct pglist_data *pgdat = lruvec_pgdat(lruvec); LIST_HEAD(pages_to_free); /* * Put back any unfreeable pages. */ while (!list_empty(page_list)) { struct page *page = lru_to_page(page_list); int lru; VM_BUG_ON_PAGE(PageLRU(page), page); list_del(&page->lru); if (unlikely(!page_evictable(page))) { spin_unlock_irq(&pgdat->lru_lock); putback_lru_page(page); spin_lock_irq(&pgdat->lru_lock); continue; } lruvec = mem_cgroup_page_lruvec(page, pgdat); SetPageLRU(page); lru = page_lru(page); add_page_to_lru_list(page, lruvec, lru); if (is_active_lru(lru)) { int file = is_file_lru(lru); int numpages = hpage_nr_pages(page); reclaim_stat->recent_rotated[file] += numpages; } if (put_page_testzero(page)) { __ClearPageLRU(page); __ClearPageActive(page); del_page_from_lru_list(page, lruvec, lru); if (unlikely(PageCompound(page))) { spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge(page); (*get_compound_page_dtor(page))(page); spin_lock_irq(&pgdat->lru_lock); } else list_add(&page->lru, &pages_to_free); } } /* * To save our caller's stack, now use input list for pages to free. */ list_splice(&pages_to_free, page_list); }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman15154.71%325.00%
Hugh Dickins8330.07%325.00%
Linus Torvalds124.35%18.33%
Rik Van Riel103.62%18.33%
Konstantin Khlebnikov93.26%18.33%
Johannes Weiner82.90%216.67%
Sasha Levin31.09%18.33%
Total276100.00%12100.00%

/* * If a kernel thread (such as nfsd for loop-back mounts) services * a backing device by writing to the page cache it sets PF_LESS_THROTTLE. * In that case we should only throttle if the backing device it is * writing to is congested. In other cases it is safe to throttle. */
static int current_may_throttle(void) { return !(current->flags & PF_LESS_THROTTLE) || current->backing_dev_info == NULL || bdi_write_congested(current->backing_dev_info); }

Contributors

PersonTokensPropCommitsCommitProp
Neil Brown31100.00%1100.00%
Total31100.00%1100.00%

/* * shrink_inactive_list() is a helper for shrink_node(). It returns the number * of reclaimed pages */
static noinline_for_stack unsigned long shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc, enum lru_list lru) { LIST_HEAD(page_list); unsigned long nr_scanned; unsigned long nr_reclaimed = 0; unsigned long nr_taken; struct reclaim_stat stat = {}; isolate_mode_t isolate_mode = 0; int file = is_file_lru(lru); struct pglist_data *pgdat = lruvec_pgdat(lruvec); struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; while (unlikely(too_many_isolated(pgdat, file, sc))) { congestion_wait(BLK_RW_ASYNC, HZ/10); /* We are about to die and free our memory. Return now. */ if (fatal_signal_pending(current)) return SWAP_CLUSTER_MAX; } lru_add_drain(); if (!sc->may_unmap) isolate_mode |= ISOLATE_UNMAPPED; spin_lock_irq(&pgdat->lru_lock); nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list, &nr_scanned, sc, isolate_mode, lru); __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); reclaim_stat->recent_scanned[file] += nr_taken; if (global_reclaim(sc)) { __mod_node_page_state(pgdat, NR_PAGES_SCANNED, nr_scanned); if (current_is_kswapd()) __count_vm_events(PGSCAN_KSWAPD, nr_scanned); else __count_vm_events(PGSCAN_DIRECT, nr_scanned); } spin_unlock_irq(&pgdat->lru_lock); if (nr_taken == 0) return 0; nr_reclaimed = shrink_page_list(&page_list, pgdat, sc, TTU_UNMAP, &stat, false); spin_lock_irq(&pgdat->lru_lock); if (global_reclaim(sc)) { if (current_is_kswapd()) __count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed); else __count_vm_events(PGSTEAL_DIRECT, nr_reclaimed); } putback_inactive_pages(lruvec, &page_list); __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge_list(&page_list); free_hot_cold_page_list(&page_list, true); /* * If reclaim is isolating dirty pages under writeback, it implies * that the long-lived page allocation rate is exceeding the page * laundering rate. Either the global limits are not being effective * at throttling processes due to the page distribution throughout * zones or there is heavy usage of a slow backing device. The * only option is to throttle from reclaim context which is not ideal * as there is no guarantee the dirtying process is throttled in the * same way balance_dirty_pages() manages. * * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number * of pages under pages flagged for immediate reclaim and stall if any * are encountered in the nr_immediate check below. */ if (stat.nr_writeback && stat.nr_writeback == nr_taken) set_bit(PGDAT_WRITEBACK, &pgdat->flags); /* * Legacy memcg will stall in page writeback so avoid forcibly * stalling here. */ if (sane_reclaim(sc)) { /* * Tag a zone as congested if all the dirty pages scanned were * backed by a congested BDI and wait_iff_congested will stall. */ if (stat.nr_dirty && stat.nr_dirty == stat.nr_congested) set_bit(PGDAT_CONGESTED, &pgdat->flags); /* * If dirty pages are scanned that are not queued for IO, it * implies that flushers are not doing their job. This can * happen when memory pressure pushes dirty pages to the end of * the LRU before the dirty limits are breached and the dirty * data has expired. It can also happen when the proportion of * dirty pages grows not through writes but through memory * pressure reclaiming all the clean cache. And in some cases, * the flushers simply cannot keep up with the allocation * rate. Nudge the flusher threads in case they are asleep, but * also allow kswapd to start writing pages during reclaim. */ if (stat.nr_unqueued_dirty == nr_taken) { wakeup_flusher_threads(0, WB_REASON_VMSCAN); set_bit(PGDAT_DIRTY, &pgdat->flags); } /* * If kswapd scans pages marked marked for immediate * reclaim and under writeback (nr_immediate), it implies * that pages are cycling through the LRU faster than * they are written so also forcibly stall. */ if (stat.nr_immediate && current_may_throttle()) congestion_wait(BLK_RW_ASYNC, HZ/10); } /* * Stall direct reclaim for IO completions if underlying BDIs or zone * is congested. Allow kswapd to continue until it starts encountering * unqueued dirty pages or cycling through the LRU too quickly. */ if (!sc->hibernation_mode && !current_is_kswapd() && current_may_throttle()) wait_iff_congested(pgdat, BLK_RW_ASYNC, HZ/10); trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, nr_scanned, nr_reclaimed, stat.nr_dirty, stat.nr_writeback, stat.nr_congested, stat.nr_immediate, stat.nr_activate, stat.nr_ref_keep, stat.nr_unmap_fail, sc->priority, file); return nr_reclaimed; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman15129.32%1425.00%
Johannes Weiner7414.37%610.71%
Michal Hocko479.13%23.57%
Konstantin Khlebnikov397.57%712.50%
Andrew Morton366.99%58.93%
Rik Van Riel356.80%23.57%
Hugh Dickins316.02%35.36%
Martin Hicks275.24%11.79%
MinChan Kim163.11%35.36%
Hillf Danton142.72%23.57%
Ying Han132.52%11.79%
Motohiro Kosaki112.14%23.57%
Nicholas Piggin71.36%11.79%
Neil Brown61.17%11.79%
Tejun Heo20.39%11.79%
Andy Whitcroft20.39%11.79%
Shantanu Goel10.19%11.79%
Lee Schermerhorn10.19%11.79%
Linus Torvalds10.19%11.79%
Christoph Lameter10.19%11.79%
Total515100.00%56100.00%

/* * This moves pages from the active list to the inactive list. * * We move them the other way if the page is referenced by one or more * processes, from rmap. * * If the pages are mostly unmapped, the processing is fast and it is * appropriate to hold zone_lru_lock across the whole operation. But if * the pages are mapped, the processing is slow (page_referenced()) so we * should drop zone_lru_lock around each page. It's impossible to balance * this, so instead we remove the pages from the LRU while processing them. * It is safe to rely on PG_active against the non-LRU pages in here because * nobody will play with that bit on a non-LRU page. * * The downside is that we have to touch page->_refcount against each page. * But we had to alter page->flags anyway. * * Returns the number of pages moved to the given lru. */
static unsigned move_active_pages_to_lru(struct lruvec *lruvec, struct list_head *list, struct list_head *pages_to_free, enum lru_list lru) { struct pglist_data *pgdat = lruvec_pgdat(lruvec); struct page *page; int nr_pages; int nr_moved = 0; while (!list_empty(list)) { page = lru_to_page(list); lruvec = mem_cgroup_page_lruvec(page, pgdat); VM_BUG_ON_PAGE(PageLRU(page), page); SetPageLRU(page); nr_pages = hpage_nr_pages(page); update_lru_size(lruvec, lru, page_zonenum(page), nr_pages); list_move(&page->lru, &lruvec->lists[lru]); if (put_page_testzero(page)) { __ClearPageLRU(page); __ClearPageActive(page); del_page_from_lru_list(page, lruvec, lru); if (unlikely(PageCompound(page))) { spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge(page); (*get_compound_page_dtor(page))(page); spin_lock_irq(&pgdat->lru_lock); } else list_add(&page->lru, pages_to_free); } else { nr_moved += nr_pages; } } if (!is_active_lru(lru)) __count_vm_events(PGDEACTIVATE, nr_moved); return nr_moved; }

Contributors

PersonTokensPropCommitsCommitProp
Fengguang Wu10344.02%19.09%
Hugh Dickins7933.76%327.27%
Mel Gorman177.26%19.09%
Michal Hocko177.26%218.18%
Johannes Weiner156.41%327.27%
Sasha Levin31.28%19.09%
Total234100.00%11100.00%


static void shrink_active_list(unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc, enum lru_list lru) { unsigned long nr_taken; unsigned long nr_scanned; unsigned long vm_flags; LIST_HEAD(l_hold); /* The pages which were snipped off */ LIST_HEAD(l_active); LIST_HEAD(l_inactive); struct page *page; struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; unsigned nr_deactivate, nr_activate; unsigned nr_rotated = 0; isolate_mode_t isolate_mode = 0; int file = is_file_lru(lru); struct pglist_data *pgdat = lruvec_pgdat(lruvec); lru_add_drain(); if (!sc->may_unmap) isolate_mode |= ISOLATE_UNMAPPED; spin_lock_irq(&pgdat->lru_lock); nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold, &nr_scanned, sc, isolate_mode, lru); __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken); reclaim_stat->recent_scanned[file] += nr_taken; if (global_reclaim(sc)) __mod_node_page_state(pgdat, NR_PAGES_SCANNED, nr_scanned); __count_vm_events(PGREFILL, nr_scanned); spin_unlock_irq(&pgdat->lru_lock); while (!list_empty(&l_hold)) { cond_resched(); page = lru_to_page(&l_hold); list_del(&page->lru); if (unlikely(!page_evictable(page))) { putback_lru_page(page); continue; } if (unlikely(buffer_heads_over_limit)) { if (page_has_private(page) && trylock_page(page)) { if (page_has_private(page)) try_to_release_page(page, 0); unlock_page(page); } } if (page_referenced(page, 0, sc->target_mem_cgroup, &vm_flags)) { nr_rotated += hpage_nr_pages(page); /* * Identify referenced, file-backed active pages and * give them one more trip around the active list. So * that executable code get better chances to stay in * memory under moderate memory pressure. Anon pages * are not likely to be evicted by use-once streaming * IO, plus JVM can create lots of anon VM_EXEC pages, * so we ignore them here. */ if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { list_add(&page->lru, &l_active); continue; } } ClearPageActive(page); /* we are de-activating */ list_add(&page->lru, &l_inactive); } /* * Move pages back to the lru list. */ spin_lock_irq(&pgdat->lru_lock); /* * Count referenced pages from currently used mappings as rotated, * even though only some of them are actually re-activated. This * helps balance scan pressure between file and anonymous pages in * get_scan_count. */ reclaim_stat->recent_rotated[file] += nr_rotated; nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru); nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE); __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken); spin_unlock_irq(&pgdat->lru_lock); mem_cgroup_uncharge_list(&l_hold); free_hot_cold_page_list(&l_hold, true); trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate, nr_deactivate, nr_rotated, sc->priority, file); }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman7315.84%48.33%
Fengguang Wu6113.23%48.33%
Andrew Morton4810.41%714.58%
Kamezawa Hiroyuki398.46%12.08%
Rik Van Riel388.24%48.33%
Motohiro Kosaki378.03%48.33%
Hugh Dickins337.16%48.33%
Michal Hocko306.51%12.08%
Konstantin Khlebnikov286.07%48.33%
Johannes Weiner275.86%612.50%
Lee Schermerhorn194.12%12.08%
MinChan Kim132.82%12.08%
Christoph Lameter51.08%24.17%
Hillf Danton30.65%12.08%
Linus Torvalds30.65%24.17%
Ingo Molnar30.65%12.08%
Jerome Marchand10.22%12.08%
Total461100.00%48100.00%

/* * The inactive anon list should be small enough that the VM never has * to do too much work. * * The inactive file list should be small enough to leave most memory * to the established workingset on the scan-resistant active list, * but large enough to avoid thrashing the aggregate readahead window. * * Both inactive lists should also be large enough that each inactive * page has a chance to be referenced again before it is reclaimed. * * The inactive_ratio is the target ratio of ACTIVE to INACTIVE pages * on this LRU, maintained by the pageout code. A zone->inactive_ratio * of 3 means 3:1 or 25% of the pages are kept on the inactive list. * * total target max * memory ratio inactive * ------------------------------------- * 10MB 1 5MB * 100MB 1 50MB * 1GB 3 250MB * 10GB 10 0.9GB * 100GB 31 3GB * 1TB 101 10GB * 10TB 320 32GB */
static bool inactive_list_is_low(struct lruvec *lruvec, bool file, struct scan_control *sc, bool trace) { unsigned long inactive_ratio; unsigned long inactive, active; enum lru_list inactive_lru = file * LRU_FILE; enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE; unsigned long gb; /* * If we don't have swap space, anonymous page deactivation * is pointless. */ if (!file && !total_swap_pages) return false; inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx); active = lruvec_lru_size(lruvec, active_lru, sc->reclaim_idx); gb = (inactive + active) >> (30 - PAGE_SHIFT); if (gb) inactive_ratio = int_sqrt(10 * gb); else inactive_ratio = 1; if (trace) trace_mm_vmscan_inactive_list_is_low(lruvec_pgdat(lruvec)->node_id, sc->reclaim_idx, lruvec_lru_size(lruvec, inactive_lru, MAX_NR_ZONES), inactive, lruvec_lru_size(lruvec, active_lru, MAX_NR_ZONES), active, inactive_ratio, file); return inactive * inactive_ratio < active; }

Contributors

PersonTokensPropCommitsCommitProp
Michal Hocko7542.86%325.00%
Rik Van Riel5833.14%325.00%
Mel Gorman1810.29%18.33%
Motohiro Kosaki116.29%18.33%
MinChan Kim84.57%18.33%
Johannes Weiner31.71%216.67%
Yaowei Bai21.14%18.33%
Total175100.00%12100.00%


static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc) { if (is_active_lru(lru)) { if (inactive_list_is_low(lruvec, is_file_lru(lru), sc, true)) shrink_active_list(nr_to_scan, lruvec, sc, lru); return 0; } return shrink_inactive_list(nr_to_scan, lruvec, sc, lru); }

Contributors

PersonTokensPropCommitsCommitProp
Rik Van Riel3647.37%541.67%
Christoph Lameter2836.84%18.33%
Konstantin Khlebnikov79.21%325.00%
Michal Hocko22.63%18.33%
Mel Gorman22.63%18.33%
Hugh Dickins11.32%18.33%
Total76100.00%12100.00%

enum scan_balance { SCAN_EQUAL, SCAN_FRACT, SCAN_ANON, SCAN_FILE, }; /* * Determine how aggressively the anon and file LRU lists should be * scanned. The relative value of each set of LRU lists is determined * by looking at the fraction of the pages scanned we did rotate back * onto the active list instead of evict. * * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan */
static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, struct scan_control *sc, unsigned long *nr, unsigned long *lru_pages) { int swappiness = mem_cgroup_swappiness(memcg); struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; u64 fraction[2]; u64 denominator = 0; /* gcc */ struct pglist_data *pgdat = lruvec_pgdat(lruvec); unsigned long anon_prio, file_prio; enum scan_balance scan_balance; unsigned long anon, file; bool force_scan = false; unsigned long ap, fp; enum lru_list lru; bool some_scanned; int pass; /* * If the zone or memcg is small, nr[l] can be 0. This * results in no scanning on this priority and a potential * priority drop. Global direct reclaim can go to the next * zone and tends to have no problems. Global kswapd is for * zone balancing and it needs to scan a minimum amount. When * reclaiming for a memcg, a priority drop can cause high * latencies, so it's better to scan a minimum amount there as * well. */ if (current_is_kswapd()) { if (!pgdat_reclaimable(pgdat)) force_scan = true; if (!mem_cgroup_online(memcg)) force_scan = true; } if (!global_reclaim(sc)) force_scan = true; /* If we have no swap space, do not bother scanning anon pages. */ if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) { scan_balance = SCAN_FILE; goto out; } /* * Global reclaim will swap to prevent OOM even with no * swappiness, but memcg users want to use this knob to * disable swapping for individual groups completely when * using the memory controller's swap limit feature would be * too expensive. */ if (!global_reclaim(sc) && !swappiness) { scan_balance = SCAN_FILE; goto out; } /* * Do not apply any pressure balancing cleverness when the * system is close to OOM, scan both anon and file equally * (unless the swappiness setting disagrees with swapping). */ if (!sc->priority && swappiness) { scan_balance = SCAN_EQUAL; goto out; } /* * Prevent the reclaimer from falling into the cache trap: as * cache pages start out inactive, every cache fault will tip * the scan balance towards the file LRU. And as the file LRU * shrinks, so does the window for rotation from references. * This means we have a runaway feedback loop where a tiny * thrashing file LRU becomes infinitely more attractive than * anon pages. Try to detect this based on file LRU size. */ if (global_reclaim(sc)) { unsigned long pgdatfile; unsigned long pgdatfree; int z; unsigned long total_high_wmark = 0; pgdatfree = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES); pgdatfile = node_page_state(pgdat, NR_ACTIVE_FILE) + node_page_state(pgdat, NR_INACTIVE_FILE); for (z = 0; z < MAX_NR_ZONES; z++) { struct zone *zone = &pgdat->node_zones[z]; if (!managed_zone(zone)) continue; total_high_wmark += high_wmark_pages(zone); } if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) { scan_balance = SCAN_ANON; goto out; } } /* * If there is enough inactive page cache, i.e. if the size of the * inactive list is greater than that of the active list *and* the * inactive list actually has some pages to scan on this priority, we * do not reclaim anything from the anonymous working set right now. * Without the second condition we could end up never scanning an * lruvec even if it has plenty of old anonymous pages unless the * system is under heavy pressure. */ if (!inactive_list_is_low(lruvec, true, sc, false) && lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) { scan_balance = SCAN_FILE; goto out; } scan_balance = SCAN_FRACT; /* * With swappiness at 100, anonymous and file have the same priority. * This scanning priority is essentially the inverse of IO cost. */ anon_prio = swappiness; file_prio = 200 - anon_prio; /* * OK, so we have swap space and a fair amount of page cache * pages. We use the recently rotated / recently scanned * ratios to determine how valuable each cache is. * * Because workloads change over time (and to avoid overflow) * we keep these statistics as a floating average, which ends * up weighing recent references more than old ones. * * anon in [0], file in [1] */ anon = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON, MAX_NR_ZONES) + lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, MAX_NR_ZONES); file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) + lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES); spin_lock_irq(&pgdat->lru_lock); if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { reclaim_stat->recent_scanned[0] /= 2; reclaim_stat->recent_rotated[0] /= 2; } if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { reclaim_stat->recent_scanned[1] /= 2; reclaim_stat->recent_rotated[1] /= 2; } /* * The amount of pressure on anon vs file pages is inversely * proportional to the fraction of recently scanned pages on * each list that were recently referenced and in active use. */ ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); ap /= reclaim_stat->recent_rotated[0] + 1; fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); fp /= reclaim_stat->recent_rotated[1] + 1; spin_unlock_irq(&pgdat->lru_lock); fraction[0] = ap; fraction[1] = fp; denominator = ap + fp + 1; out: some_scanned = false; /* Only use force_scan on second pass. */ for (pass = 0; !some_scanned && pass < 2; pass++) { *lru_pages = 0; for_each_evictable_lru(lru) { int file = is_file_lru(lru); unsigned long size; unsigned long scan; size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); scan = size >> sc->priority; if (!scan && pass && force_scan) scan = min(size, SWAP_CLUSTER_MAX); switch (scan_balance) { case SCAN_EQUAL: /* Scan lists relative to size */ break; case SCAN_FRACT: /* * Scan types proportional to swappiness and * their relative recent reclaim efficiency. */ scan = div64_u64(scan * fraction[file], denominator); break; case SCAN_FILE: case SCAN_ANON: /* Scan one type exclusively */ if ((scan_balance == SCAN_FILE) != file) { size = 0; scan = 0; } break; default: /* Look ma, no brain */ BUG(); } *lru_pages += size; nr[lru] = scan; /* * Skip the second pass and don't force_scan, * if we found something to scan. */ some_scanned |= !!scan; } } }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Weiner21327.84%1126.83%
Rik Van Riel15720.52%49.76%
Mel Gorman8210.72%37.32%
David Shaohua Li547.06%12.44%
Jerome Marchand455.88%12.44%
Vladimir Davydov445.75%512.20%
Kamezawa Hiroyuki395.10%12.44%
Suleiman Souhlal395.10%12.44%
Motohiro Kosaki334.31%24.88%
Michal Hocko212.75%49.76%
Konstantin Khlebnikov162.09%37.32%
Fengguang Wu121.57%12.44%
Hugh Dickins50.65%24.88%
Lisa Du30.39%12.44%
Christoph Lameter20.26%12.44%
Total765100.00%41100.00%

/* * This is a basic per-node page freer. Used by both kswapd and direct reclaim. */
static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memcg, struct scan_control *sc, unsigned long *lru_pages) { struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); unsigned long nr[NR_LRU_LISTS]; unsigned long targets[NR_LRU_LISTS]; unsigned long nr_to_scan; enum lru_list lru; unsigned long nr_reclaimed = 0; unsigned long nr_to_reclaim = sc->nr_to_reclaim; struct blk_plug plug; bool scan_adjusted; get_scan_count(lruvec, memcg, sc, nr, lru_pages); /* Record the original scan target for proportional adjustments later */ memcpy(targets, nr, sizeof(nr)); /* * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal * event that can occur when there is little memory pressure e.g. * multiple streaming readers/writers. Hence, we do not abort scanning * when the requested number of pages are reclaimed when scanning at * DEF_PRIORITY on the assumption that the fact we are direct * reclaiming implies that kswapd is not keeping up and it is best to * do a batch of work at once. For memcg reclaim one check is made to * abort proportional reclaim if either the file or anon lru has already * dropped to zero at the first pass. */ scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() && sc->priority == DEF_PRIORITY); blk_start_plug(&plug); while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || nr[LRU_INACTIVE_FILE]) { unsigned long nr_anon, nr_file, percentage; unsigned long nr_scanned; for_each_evictable_lru(lru) { if (nr[lru]) { nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX); nr[lru] -= nr_to_scan; nr_reclaimed += shrink_list(lru, nr_to_scan, lruvec, sc); } } cond_resched(); if (nr_reclaimed < nr_to_reclaim || scan_adjusted) continue; /* * For kswapd and memcg, reclaim at least the number of pages * requested. Ensure that the anon and file LRUs are scanned * proportionally what was requested by get_scan_count(). We * stop reclaiming one LRU and reduce the amount scanning * proportional to the original scan target. */ nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE]; nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON]; /* * It's just vindictive to attack the larger once the smaller * has gone to zero. And given the way we stop scanning the * smaller below, this makes sure that we only make one nudge * towards proportionality once we've got nr_to_reclaim. */ if (!nr_file || !nr_anon) break; if (nr_file > nr_anon) { unsigned long scan_target = targets[LRU_INACTIVE_ANON] + targets[LRU_ACTIVE_ANON] + 1; lru = LRU_BASE; percentage = nr_anon * 100 / scan_target; } else { unsigned long scan_target = targets[LRU_INACTIVE_FILE] + targets[LRU_ACTIVE_FILE] + 1; lru = LRU_FILE; percentage = nr_file * 100 / scan_target; } /* Stop scanning the smaller of the LRU */ nr[lru] = 0; nr[lru + LRU_ACTIVE] = 0; /* * Recalculate the other LRU scan count based on its original * scan target and the percentage scanning already complete */ lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; nr_scanned = targets[lru] - nr[lru]; nr[lru] = targets[lru] * (100 - percentage) / 100; nr[lru] -= min(nr[lru], nr_scanned); lru += LRU_ACTIVE; nr_scanned = targets[lru] - nr[lru]; nr[lru] = targets[lru] * (100 - percentage) / 100; nr[lru] -= min(nr[lru], nr_scanned); scan_adjusted = true; } blk_finish_plug(&plug); sc->nr_reclaimed += nr_reclaimed; /* * Even if we did not try to evict anon pages at all, we want to * rebalance the anon lru active/inactive ratio. */ if (inactive_list_is_low(lruvec, false, sc, true)) shrink_active_list(SWAP_CLUSTER_MAX, lruvec, sc, LRU_ACTIVE_ANON); }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman29860.82%436.36%
Johannes Weiner17034.69%327.27%
Vladimir Davydov142.86%19.09%
Michal Hocko51.02%218.18%
Rik Van Riel30.61%19.09%
Total490100.00%11100.00%

/* Use reclaim/compaction for costly allocs or under memory pressure */
static bool in_reclaim_compaction(struct scan_control *sc) { if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && (sc->order > PAGE_ALLOC_COSTLY_ORDER || sc->priority < DEF_PRIORITY - 2)) return true; return false; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman3886.36%133.33%
Kirill A. Shutemov49.09%133.33%
Konstantin Khlebnikov24.55%133.33%
Total44100.00%3100.00%

/* * Reclaim/compaction is used for high-order allocation requests. It reclaims * order-0 pages before compacting the zone. should_continue_reclaim() returns * true if more pages should be reclaimed such that when the page allocator * calls try_to_compact_zone() that it will have enough free pages to succeed. * It will give up earlier than that if there is difficulty reclaiming pages. */
static inline bool should_continue_reclaim(struct pglist_data *pgdat, unsigned long nr_reclaimed, unsigned long nr_scanned, struct scan_control *sc) { unsigned long pages_for_compaction; unsigned long inactive_lru_pages; int z; /* If not in reclaim/compaction mode, stop */ if (!in_reclaim_compaction(sc)) return false; /* Consider stopping depending on scan and reclaim activity */ if (sc->gfp_mask & __GFP_REPEAT) { /* * For __GFP_REPEAT allocations, stop reclaiming if the * full LRU list has been scanned and we are still failing * to reclaim pages. This full LRU scan is potentially * expensive but a __GFP_REPEAT caller really wants to succeed */ if (!nr_reclaimed && !nr_scanned) return false; } else { /* * For non-__GFP_REPEAT allocations which can presumably * fail without consequence, stop if we failed to reclaim * any pages from the last SWAP_CLUSTER_MAX number of * pages that were scanned. This will return to the * caller faster at the risk reclaim/compaction and * the resulting allocation attempt fails */ if (!nr_reclaimed) return false; } /* * If we have not reclaimed enough pages for compaction and the * inactive lists are large enough, continue reclaiming */ pages_for_compaction = compact_gap(sc->order); inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); if (get_nr_swap_pages() > 0) inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); if (sc->nr_reclaimed < pages_for_compaction && inactive_lru_pages > pages_for_compaction) return true; /* If compaction would go ahead or the allocation would succeed, stop */ for (z = 0; z <= sc->reclaim_idx; z++) { struct zone *zone = &pgdat->node_zones[z]; if (!managed_zone(zone)) continue; switch (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx)) { case COMPACT_SUCCESS: case COMPACT_CONTINUE: return false; default: /* check next zone */ ; } } return true; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman18790.34%650.00%
MinChan Kim83.86%18.33%
Vlastimil Babka73.38%325.00%
Johannes Weiner31.45%18.33%
Shaohua Li20.97%18.33%
Total207100.00%12100.00%


static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) { struct reclaim_state *reclaim_state = current->reclaim_state; unsigned long nr_reclaimed, nr_scanned; bool reclaimable = false; do { struct mem_cgroup *root = sc->target_mem_cgroup; struct mem_cgroup_reclaim_cookie reclaim = { .pgdat = pgdat, .priority = sc->priority, }; unsigned long node_lru_pages = 0; struct mem_cgroup *memcg; nr_reclaimed = sc->nr_reclaimed; nr_scanned = sc->nr_scanned; memcg = mem_cgroup_iter(root, NULL, &reclaim); do { unsigned long lru_pages; unsigned long reclaimed; unsigned long scanned; if (mem_cgroup_low(root, memcg)) { if (!sc->may_thrash) continue; mem_cgroup_events(memcg, MEMCG_LOW, 1); } reclaimed = sc->nr_reclaimed; scanned = sc->nr_scanned; shrink_node_memcg(pgdat, memcg, sc, &lru_pages); node_lru_pages += lru_pages; if (memcg) shrink_slab(sc->gfp_mask, pgdat->node_id, memcg, sc->nr_scanned - scanned, lru_pages); /* Record the group's reclaim efficiency */ vmpressure(sc->gfp_mask, memcg, false, sc->nr_scanned - scanned, sc->nr_reclaimed - reclaimed); /* * Direct reclaim and kswapd have to scan all memory * cgroups to fulfill the overall scan target for the * node. * * Limit reclaim, on the other hand, only cares about * nr_to_reclaim pages to be reclaimed and it will * retry with decreasing priority if one round over the * whole hierarchy is not sufficient. */ if (!global_reclaim(sc) && sc->nr_reclaimed >= sc->nr_to_reclaim) { mem_cgroup_iter_break(root, memcg); break; } } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); /* * Shrink the slab caches in the same proportion that * the eligible LRU pages were scanned. */ if (global_reclaim(sc)) shrink_slab(sc->gfp_mask, pgdat->node_id, NULL, sc->nr_scanned - nr_scanned, node_lru_pages); if (reclaim_state) { sc->nr_reclaimed += reclaim_state->reclaimed_slab; reclaim_state->reclaimed_slab = 0; } /* Record the subtree's reclaim efficiency */ vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, sc->nr_scanned - nr_scanned, sc->nr_reclaimed - nr_reclaimed); if (sc->nr_reclaimed - nr_reclaimed) reclaimable = true; } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, sc->nr_scanned - nr_scanned, sc)); return reclaimable; }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Weiner24966.22%933.33%
Vladimir Davydov4511.97%311.11%
Anton Vorontsov236.12%13.70%
Andrew Morton215.59%311.11%
Mel Gorman195.05%414.81%
Michal Hocko82.13%13.70%
Linus Torvalds51.33%311.11%
Linus Torvalds (pre-git)30.80%13.70%
Konstantin Khlebnikov20.53%13.70%
Motohiro Kosaki10.27%13.70%
Total376100.00%27100.00%

/* * Returns true if compaction should go ahead for a costly-order request, or * the allocation would already succeed without compaction. Return false if we * should reclaim first. */
static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) { unsigned long watermark; enum compact_result suitable; suitable = compaction_suitable(zone, sc->order, 0, sc->reclaim_idx); if (suitable == COMPACT_SUCCESS) /* Allocation should succeed already. Don't reclaim. */ return true; if (suitable == COMPACT_SKIPPED) /* Compaction cannot yet proceed. Do reclaim. */ return false; /* * Compaction is already possible, but it takes time to run and there * are potentially other callers using the pages just freed. So proceed * with reclaim to make a buffer of free pages available to give * compaction a reasonable chance of completing and allocating the page. * Note that we won't actually reclaim the whole buffer in one attempt * as the target watermark in should_continue_reclaim() is lower. But if * we are already above the high+gap watermark, don't reclaim at all. */ watermark = high_wmark_pages(zone) + compact_gap(sc->order); return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx); }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman5358.24%250.00%
Vlastimil Babka3841.76%250.00%
Total91100.00%4100.00%

/* * This is the direct reclaim path, for page-allocating processes. We only * try to reclaim pages from zones which will satisfy the caller's allocation * request. * * If a zone is deemed to be full of pinned pages then just give it a light * scan then give up on it. */
static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) { struct zoneref *z; struct zone *zone; unsigned long nr_soft_reclaimed; unsigned long nr_soft_scanned; gfp_t orig_mask; pg_data_t *last_pgdat = NULL; /* * If the number of buffer_heads in the machine exceeds the maximum * allowed level, force direct reclaim to scan the highmem zone as * highmem pages could be pinning lowmem pages storing buffer_heads */ orig_mask = sc->gfp_mask; if (buffer_heads_over_limit) { sc->gfp_mask |= __GFP_HIGHMEM; sc->reclaim_idx = gfp_zone(sc->gfp_mask); } for_each_zone_zonelist_nodemask(zone, z, zonelist, sc->reclaim_idx, sc->nodemask) { /* * Take care memory controller reclaiming has small influence * to global LRU. */ if (global_reclaim(sc)) { if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) continue; if (sc->priority != DEF_PRIORITY && !pgdat_reclaimable(zone->zone_pgdat)) continue; /* Let kswapd poll it */ /* * If we already have plenty of memory free for * compaction in this zone, don't free any more. * Even though compaction is invoked for any * non-zero order, only frequent costly order * reclamation is disruptive enough to become a * noticeable problem, like transparent huge * page allocations. */ if (IS_ENABLED(CONFIG_COMPACTION) && sc->order > PAGE_ALLOC_COSTLY_ORDER && compaction_ready(zone, sc)) { sc->compaction_ready = true; continue; } /* * Shrink each node in the zonelist once. If the * zonelist is ordered by zone (not the default) then a * node may be shrunk multiple times but in that case * the user prefers lower zones being preserved. */ if (zone->zone_pgdat == last_pgdat) continue; /* * This steals pages from memory cgroups over softlimit * and returns the number of reclaimed pages and * scanned pages. This works for global memory pressure * and balancing, not for a memcg's limit. */ nr_soft_scanned = 0; nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone->zone_pgdat, sc->order, sc->gfp_mask, &nr_soft_scanned); sc->nr_reclaimed += nr_soft_reclaimed; sc->nr_scanned += nr_soft_scanned; /* need some check for avoid more shrink_zone() */ } /* See comment about same check for global reclaim above */ if (zone->zone_pgdat == last_pgdat) continue; last_pgdat = zone->zone_pgdat; shrink_node(zone->zone_pgdat, sc); } /* * Restore to original mask to avoid the impact on the caller if we * promoted it to __GFP_HIGHMEM. */ sc->gfp_mask = orig_mask; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman8937.39%1029.41%
Andrew Morton7230.25%823.53%
Weijie Yang166.72%12.94%
Kamezawa Hiroyuki135.46%38.82%
Johannes Weiner125.04%25.88%
Paul Jackson104.20%38.82%
Rik Van Riel104.20%12.94%
Lisa Du52.10%12.94%
Kirill A. Shutemov41.68%12.94%
Vladimir Davydov31.26%12.94%
Konstantin Khlebnikov20.84%12.94%
MinChan Kim10.42%12.94%
Michal Hocko10.42%12.94%
Total238100.00%34100.00%

/* * This is the main entry point to direct page reclaim. * * If a full scan of the inactive list fails to free enough memory then we * are "out of memory" and something needs to be killed. * * If the caller is !__GFP_FS then the probability of a failure is reasonably * high - the zone may be full of dirty or under-writeback pages, which this * caller can't do much about. We kick the writeback threads and take explicit * naps in the hope that some of these pages can be written. But if the * allocating task holds filesystem locks which prevent writeout this might not * work, and the allocation attempt will fail. * * returns: 0, if no pages reclaimed * else, the number of pages reclaimed */
static unsigned long do_try_to_free_pages(struct zonelist *zonelist, struct scan_control *sc) { int initial_priority = sc->priority; retry: delayacct_freepages_start(); if (global_reclaim(sc)) __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1); do { vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, sc->priority); sc->nr_scanned = 0; shrink_zones(zonelist, sc); if (sc->nr_reclaimed >= sc->nr_to_reclaim) break; if (sc->compaction_ready) break; /* * If we're getting trouble reclaiming, start doing * writepage even in laptop mode. */ if (sc->priority < DEF_PRIORITY - 2) sc->may_writepage = 1; } while (--sc->priority >= 0); delayacct_freepages_end(); if (sc->nr_reclaimed) return sc->nr_reclaimed; /* Aborted reclaim to try compaction? don't OOM, then */ if (sc->compaction_ready) return 1; /* Untapped cgroup reserves? Don't OOM, retry. */ if (!sc->may_thrash) { sc->priority = initial_priority; sc->may_thrash = 1; goto retry; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Weiner4626.29%39.38%
Mel Gorman1810.29%515.62%
Andrew Morton1810.29%825.00%
MinChan Kim179.71%13.12%
Anton Vorontsov158.57%13.12%
Motohiro Kosaki137.43%26.25%
Konstantin Khlebnikov116.29%13.12%
Balbir Singh84.57%13.12%
Linus Torvalds74.00%39.38%
Kamezawa Hiroyuki63.43%13.12%
Keika Kobayashi63.43%13.12%
Linus Torvalds (pre-git)42.29%13.12%
Rik Van Riel21.14%13.12%
Nicholas Piggin21.14%13.12%
Nigel Cunningham10.57%13.12%
Christoph Lameter10.57%13.12%
Total175100.00%32100.00%


static bool pfmemalloc_watermark_ok(pg_data_t *pgdat) { struct zone *zone; unsigned long pfmemalloc_reserve = 0; unsigned long free_pages = 0; int i; bool wmark_ok; for (i = 0; i <= ZONE_NORMAL; i++) { zone = &pgdat->node_zones[i]; if (!managed_zone(zone) || pgdat_reclaimable_pages(pgdat) == 0) continue; pfmemalloc_reserve += min_wmark_pages(zone); free_pages += zone_page_state(zone, NR_FREE_PAGES); } /* If there are no reserves (unexpected config) then do not throttle */ if (!pfmemalloc_reserve) return true; wmark_ok = free_pages > pfmemalloc_reserve / 2; /* kswapd must be awake if processes are being throttled */ if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) { pgdat->kswapd_classzone_idx = min(pgdat->kswapd_classzone_idx, (enum zone_type)ZONE_NORMAL); wake_up_interruptible(&pgdat->kswapd_wait); } return wmark_ok; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman14696.69%583.33%
Nishanth Aravamudan53.31%116.67%
Total151100.00%6100.00%

/* * Throttle direct reclaimers if backing storage is backed by the network * and the PFMEMALLOC reserve for the preferred node is getting dangerously * depleted. kswapd will continue to make progress and wake the processes * when the low watermark is reached. * * Returns true if a fatal signal was delivered during throttling. If this * happens, the page allocator should not consider triggering the OOM killer. */
static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, nodemask_t *nodemask) { struct zoneref *z; struct zone *zone; pg_data_t *pgdat = NULL; /* * Kernel threads should not be throttled as they may be indirectly * responsible for cleaning pages necessary for reclaim to make forward * progress. kjournald for example may enter direct reclaim while * committing a transaction where throttling it could forcing other * processes to block on log_wait_commit(). */ if (current->flags & PF_KTHREAD) goto out; /* * If a fatal signal is pending, this process should not throttle. * It should return quickly so it can exit and free its memory */ if (fatal_signal_pending(current)) goto out; /* * Check if the pfmemalloc reserves are ok by finding the first node * with a usable ZONE_NORMAL or lower zone. The expectation is that * GFP_KERNEL will be required for allocating network buffers when * swapping over the network so ZONE_HIGHMEM is unusable. * * Throttling is based on the first usable node and throttled processes * wait on a queue until kswapd makes progress and wakes them. There * is an affinity then between processes waking up and where reclaim * progress has been made assuming the process wakes on the same node. * More importantly, processes running on remote nodes will not compete * for remote pfmemalloc reserves and processes on different nodes * should make reasonable progress. */ for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nodemask) { if (zone_idx(zone) > ZONE_NORMAL) continue; /* Throttle based on the first usable node */ pgdat = zone->zone_pgdat; if (pfmemalloc_watermark_ok(pgdat)) goto out; break; } /* If no zone was usable by the allocation flags then do not throttle */ if (!pgdat) goto out; /* Account for the throttling */ count_vm_event(PGSCAN_DIRECT_THROTTLE); /* * If the caller cannot enter the filesystem, it's possible that it * is due to the caller holding an FS lock or performing a journal * transaction in the case of a filesystem like ext[3|4]. In this case, * it is not safe to block on pfmemalloc_wait as kswapd could be * blocked waiting on the same lock. Instead, throttle for up to a * second before continuing. */ if (!(gfp_mask & __GFP_FS)) { wait_event_interruptible_timeout(pgdat->pfmemalloc_wait, pfmemalloc_watermark_ok(pgdat), HZ); goto check_pending; } /* Throttle until kswapd wakes the process */ wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, pfmemalloc_watermark_ok(pgdat)); check_pending: if (fatal_signal_pending(current)) return true; out: return false; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman17599.43%480.00%
Michael S. Tsirkin10.57%120.00%
Total176100.00%5100.00%


unsigned long try_to_free_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *nodemask) { unsigned long nr_reclaimed; struct scan_control sc = { .nr_to_reclaim = SWAP_CLUSTER_MAX, .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), .reclaim_idx = gfp_zone(gfp_mask), .order = order, .nodemask = nodemask, .priority = DEF_PRIORITY, .may_writepage = !laptop_mode, .may_unmap = 1, .may_swap = 1, }; /* * Do not enter reclaim if fatal signal was delivered while throttled. * 1 is returned so that the page allocator does not OOM kill at this * point. */ if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask)) return 1; trace_mm_vmscan_direct_reclaim_begin(order, sc.may_writepage, gfp_mask, sc.reclaim_idx); nr_reclaimed = do_try_to_free_pages(zonelist, &sc); trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); return nr_reclaimed; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman5540.74%650.00%
Balbir Singh4432.59%18.33%
Johannes Weiner1813.33%18.33%
Ming Lei75.19%18.33%
Kamezawa Hiroyuki53.70%18.33%
Konstantin Khlebnikov32.22%18.33%
Motohiro Kosaki32.22%18.33%
Total135100.00%12100.00%

#ifdef CONFIG_MEMCG
unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, gfp_t gfp_mask, bool noswap, pg_data_t *pgdat, unsigned long *nr_scanned) { struct scan_control sc = { .nr_to_reclaim = SWAP_CLUSTER_MAX, .target_mem_cgroup = memcg, .may_writepage = !laptop_mode, .may_unmap = 1, .reclaim_idx = MAX_NR_ZONES - 1, .may_swap = !noswap, }; unsigned long lru_pages; sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, sc.may_writepage, sc.gfp_mask, sc.reclaim_idx); /* * NOTE: Although we can get the priority field, using it * here is not a good idea, since it limits the pages we can scan. * if we don't reclaim here, the shrink_node from balance_pgdat * will pick up pages from other mem cgroup's as well. We hack * the priority and make it zero. */ shrink_node_memcg(pgdat, memcg, &sc, &lru_pages); trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); *nr_scanned = sc.nr_scanned; return sc.nr_reclaimed; }

Contributors

PersonTokensPropCommitsCommitProp
Balbir Singh6848.92%17.14%
Motohiro Kosaki2215.83%214.29%
Mel Gorman1712.23%428.57%
Ying Han1510.79%17.14%
Johannes Weiner139.35%428.57%
Konstantin Khlebnikov32.16%17.14%
Vladimir Davydov10.72%17.14%
Total139100.00%14100.00%


unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, unsigned long nr_pages, gfp_t gfp_mask, bool may_swap) { struct zonelist *zonelist; unsigned long nr_reclaimed; int nid; struct scan_control sc = { .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), .reclaim_idx = MAX_NR_ZONES - 1, .target_mem_cgroup = memcg, .priority = DEF_PRIORITY, .may_writepage = !laptop_mode, .may_unmap = 1, .may_swap = may_swap, }; /* * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't * take care of from where we get pages. So the node where we start the * scan does not need to be the current node. */ nid = mem_cgroup_select_victim_node(memcg); zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK]; trace_mm_vmscan_memcg_reclaim_begin(0, sc.may_writepage, sc.gfp_mask, sc.reclaim_idx); current->flags |= PF_MEMALLOC; nr_reclaimed = do_try_to_free_pages(zonelist, &sc); current->flags &= ~PF_MEMALLOC; trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); return nr_reclaimed; }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Weiner4929.34%420.00%
Balbir Singh4426.35%315.00%
Motohiro Kosaki3319.76%315.00%
Mel Gorman158.98%420.00%
Ying Han137.78%210.00%
Konstantin Khlebnikov52.99%15.00%
Kamezawa Hiroyuki42.40%210.00%
Aneesh Kumar K.V42.40%15.00%
Total167100.00%20100.00%

#endif
static void age_active_anon(struct pglist_data *pgdat, struct scan_control *sc) { struct mem_cgroup *memcg; if (!total_swap_pages) return; memcg = mem_cgroup_iter(NULL, NULL, NULL); do { struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg); if (inactive_list_is_low(lruvec, false, sc, true)) shrink_active_list(SWAP_CLUSTER_MAX, lruvec, sc, LRU_ACTIVE_ANON); memcg = mem_cgroup_iter(NULL, memcg, NULL); } while (memcg); }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Weiner6772.04%220.00%
Konstantin Khlebnikov1111.83%330.00%
Mel Gorman1010.75%330.00%
Rik Van Riel33.23%110.00%
Michal Hocko22.15%110.00%
Total93100.00%10100.00%


static bool zone_balanced(struct zone *zone, int order, int classzone_idx) { unsigned long mark = high_wmark_pages(zone); if (!zone_watermark_ok_safe(zone, order, mark, classzone_idx)) return false; /* * If any eligible zone is balanced then the node is not considered * to be congested or dirty */ clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags); clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags); clear_bit(PGDAT_WRITEBACK, &zone->zone_pgdat->flags); return true; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman4655.42%240.00%
Johannes Weiner2732.53%120.00%
Vlastimil Babka1012.05%240.00%
Total83100.00%5100.00%

/* * Prepare kswapd for sleeping. This verifies that there are no processes * waiting in throttle_direct_reclaim() and that watermarks have been met. * * Returns true if kswapd is ready to sleep */
static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx) { int i; /* * The throttled processes are normally woken up in balance_pgdat() as * soon as pfmemalloc_watermark_ok() is true. But there is a potential * race between when kswapd checks the watermarks and a process gets * throttled. There is also a potential race if processes get * throttled, kswapd wakes, a large process exits thereby balancing the * zones, which causes kswapd to exit balance_pgdat() before reaching * the wake up checks. If kswapd is going to sleep, no process should * be sleeping on pfmemalloc_wait, so wake them now if necessary. If * the wake up is premature, processes will wake kswapd and get * throttled again. The difference from wake ups in balance_pgdat() is * that here we are under prepare_to_wait(). */ if (waitqueue_active(&pgdat->pfmemalloc_wait)) wake_up_all(&pgdat->pfmemalloc_wait); for (i = 0; i <= classzone_idx; i++) { struct zone *zone = pgdat->node_zones + i; if (!managed_zone(zone)) continue; if (!zone_balanced(zone, order, classzone_idx)) return false; } return true; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman6167.03%583.33%
Zlatko Calusic3032.97%116.67%
Total91100.00%6100.00%

/* * kswapd shrinks a node of pages that are at or below the highest usable * zone that is currently unbalanced. * * Returns true if kswapd scanned at least the requested number of pages to * reclaim or if the lack of progress was due to pages under writeback. * This is used to determine if the scanning priority needs to be raised. */
static bool kswapd_shrink_node(pg_data_t *pgdat, struct scan_control *sc) { struct zone *zone; int z; /* Reclaim a number of pages proportional to the number of zones */ sc->nr_to_reclaim = 0; for (z = 0; z <= sc->reclaim_idx; z++) { zone = pgdat->node_zones + z; if (!managed_zone(zone)) continue; sc->nr_to_reclaim += max(high_wmark_pages(zone), SWAP_CLUSTER_MAX); } /* * Historically care was taken to put equal pressure on all zones but * now pressure is applied based on node LRU order. */ shrink_node(pgdat, sc); /* * Fragmentation may mean that the system cannot be rebalanced for * high-order allocations. If twice the allocation size has been * reclaimed then recheck watermarks only at order-0 to prevent * excessive reclaim. Assume that a process requested a high-order * can direct reclaim/compact. */ if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order)) sc->order = 0; return sc->nr_scanned >= sc->nr_to_reclaim; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman10991.60%872.73%
Vlastimil Babka86.72%218.18%
Johannes Weiner21.68%19.09%
Total119100.00%11100.00%

/* * For kswapd, balance_pgdat() will reclaim pages across a node from zones * that are eligible for use by the caller until at least one zone is * balanced. * * Returns the order kswapd finished reclaiming at. * * kswapd scans the zones in the highmem->normal->dma direction. It skips * zones which have free_pages > high_wmark_pages(zone), but once a zone is * found to have free_pages <= high_wmark_pages(zone), any page is that zone * or lower is eligible for reclaim until at least one usable zone is * balanced. */
static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) { int i; unsigned long nr_soft_reclaimed; unsigned long nr_soft_scanned; struct zone *zone; struct scan_control sc = { .gfp_mask = GFP_KERNEL, .order = order, .priority = DEF_PRIORITY, .may_writepage = !laptop_mode, .may_unmap = 1, .may_swap = 1, }; count_vm_event(PAGEOUTRUN); do { bool raise_priority = true; sc.nr_reclaimed = 0; sc.reclaim_idx = classzone_idx; /* * If the number of buffer_heads exceeds the maximum allowed * then consider reclaiming from all zones. This has a dual * purpose -- on 64-bit systems it is expected that * buffer_heads are stripped during active rotation. On 32-bit * systems, highmem pages can pin lowmem memory and shrinking * buffers can relieve lowmem pressure. Reclaim may still not * go ahead if all eligible zones for the original allocation * request are balanced to avoid excessive reclaim from kswapd. */ if (buffer_heads_over_limit) { for (i = MAX_NR_ZONES - 1; i >= 0; i--) { zone = pgdat->node_zones + i; if (!managed_zone(zone)) continue; sc.reclaim_idx = i; break; } } /* * Only reclaim if there are no eligible zones. Check from * high to low zone as allocations prefer higher zones. * Scanning from low to high zone would allow congestion to be * cleared during a very small window when a small low * zone was balanced even under extreme pressure when the * overall node may be congested. Note that sc.reclaim_idx * is not used as buffer_heads_over_limit may have adjusted * it. */ for (i = classzone_idx; i >= 0; i--) { zone = pgdat->node_zones + i; if (!managed_zone(zone)) continue; if (zone_balanced(zone, sc.order, classzone_idx)) goto out; } /* * Do some background aging of the anon list, to give * pages a chance to be referenced before reclaiming. All * pages are rotated regardless of classzone as this is * about consistent aging. */ age_active_anon(pgdat, &sc); /* * If we're getting trouble reclaiming, start doing writepage * even in laptop mode. */ if (sc.priority < DEF_PRIORITY - 2 || !pgdat_reclaimable(pgdat)) sc.may_writepage = 1; /* Call soft limit reclaim before calling shrink_node. */ sc.nr_scanned = 0; nr_soft_scanned = 0; nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(pgdat, sc.order, sc.gfp_mask, &nr_soft_scanned); sc.nr_reclaimed += nr_soft_reclaimed; /* * There should be no need to raise the scanning priority if * enough pages are already being scanned that that high * watermark would be met at 100% efficiency. */ if (kswapd_shrink_node(pgdat, &sc)) raise_priority = false; /* * If the low watermark is met there is no need for processes * to be throttled on pfmemalloc_wait as they should not be * able to safely make forward progress. Wake them */ if (waitqueue_active(&pgdat->pfmemalloc_wait) && pfmemalloc_watermark_ok(pgdat)) wake_up_all(&pgdat->pfmemalloc_wait); /* Check if kswapd should be suspending */ if (try_to_freeze() || kthread_should_stop()) break; /* * Raise priority if scanning rate is too low or there was no * progress in reclaiming pages */ if (raise_priority || !sc.nr_reclaimed) sc.priority--; } while (sc.priority >= 1); out: /* * Return the order kswapd stopped reclaiming at as * prepare_kswapd_sleep() takes it into account. If another caller * entered the allocator slow path while kswapd was awake, order will * remain at the higher level. */ return sc.order; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman17351.03%1327.08%
Andrew Morton8625.37%1225.00%
Linus Torvalds185.31%36.25%
Motohiro Kosaki113.24%24.17%
Nicholas Piggin102.95%36.25%
Johannes Weiner92.65%24.17%
Linus Torvalds (pre-git)72.06%12.08%
Rik Van Riel41.18%24.17%
Con Kolivas41.18%12.08%
Rafael J. Wysocki30.88%24.17%
Lisa Du30.88%12.08%
Konstantin Khlebnikov30.88%12.08%
Balbir Singh30.88%12.08%
Vlastimil Babka20.59%24.17%
Christoph Lameter20.59%12.08%
Andy Whitcroft10.29%12.08%
Total339100.00%48100.00%


static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order, unsigned int classzone_idx) { long remaining = 0; DEFINE_WAIT(wait); if (freezing(current) || kthread_should_stop()) return; prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); /* Try to sleep for a short interval */ if (prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { /* * Compaction records what page blocks it recently failed to * isolate pages from and skips them in the future scanning. * When kswapd is going to sleep, it is reasonable to assume * that pages and compaction may succeed so reset the cache. */ reset_isolation_suitable(pgdat); /* * We have freed the memory, now we should compact it to make * allocation of the requested order possible. */ wakeup_kcompactd(pgdat, alloc_order, classzone_idx); remaining = schedule_timeout(HZ/10); /* * If woken prematurely then reset kswapd_classzone_idx and * order. The values will either be from a wakeup request or * the previous request that slept prematurely. */ if (remaining) { pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, classzone_idx); pgdat->kswapd_order = max(pgdat->kswapd_order, reclaim_order); } finish_wait(&pgdat->kswapd_wait, &wait); prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); } /* * After a short sleep, check if it was a premature sleep. If not, then * go fully to sleep until explicitly woken up. */ if (!remaining && prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) { trace_mm_vmscan_kswapd_sleep(pgdat->node_id); /* * vmstat counters are not perfectly accurate and the estimated * value for counters such as NR_FREE_PAGES can deviate from the * true value by nr_online_cpus * threshold. To avoid the zone * watermarks being breached while under pressure, we reduce the * per-cpu vmstat threshold while kswapd is awake and restore * them before going back to sleep. */ set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); if (!kthread_should_stop()) schedule(); set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); } else { if (remaining) count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); else count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); } finish_wait(&pgdat->kswapd_wait, &wait); }

Contributors

PersonTokensPropCommitsCommitProp
Motohiro Kosaki15568.28%112.50%
Mel Gorman4921.59%450.00%
Vlastimil Babka177.49%225.00%
Aaditya Kumar62.64%112.50%
Total227100.00%8100.00%

/* * The background pageout daemon, started as a kernel thread * from the init process. * * This basically trickles out pages so that we have _some_ * free memory available even if there is no other activity * that frees anything up. This is needed for things like routing * etc, where we otherwise might have all activity going on in * asynchronous contexts that cannot page things out. * * If there are applications that are active memory-allocators * (most normal use), this basically shouldn't matter. */
static int kswapd(void *p) { unsigned int alloc_order, reclaim_order, classzone_idx; pg_data_t *pgdat = (pg_data_t*)p; struct task_struct *tsk = current; struct reclaim_state reclaim_state = { .reclaimed_slab = 0, }; const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); lockdep_set_current_reclaim_state(GFP_KERNEL); if (!cpumask_empty(cpumask)) set_cpus_allowed_ptr(tsk, cpumask); current->reclaim_state = &reclaim_state; /* * Tell the memory management that we're a "memory allocator", * and that if we need more memory we should get access to it * regardless (see "__alloc_pages()"). "kswapd" should * never get caught in the normal page freeing logic. * * (Kswapd normally doesn't need memory anyway, but sometimes * you need a small amount of memory in order to be able to * page out something else, and this flag essentially protects * us from recursively trying to free more memory as we're * trying to free the first piece of memory in the first place). */ tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; set_freezable(); pgdat->kswapd_order = alloc_order = reclaim_order = 0; pgdat->kswapd_classzone_idx = classzone_idx = 0; for ( ; ; ) { bool ret; kswapd_try_sleep: kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order, classzone_idx); /* Read the new order and classzone_idx */ alloc_order = reclaim_order = pgdat->kswapd_order; classzone_idx = pgdat->kswapd_classzone_idx; pgdat->kswapd_order = 0; pgdat->kswapd_classzone_idx = 0; ret = try_to_freeze(); if (kthread_should_stop()) break; /* * We can speed up thawing tasks if we don't call balance_pgdat * after returning from the refrigerator */ if (ret) continue; /* * Reclaim begins at the requested order but if a high-order * reclaim fails then kswapd falls back to reclaiming for * order-0. If that happens, kswapd will consider sleeping * for the order it finished reclaiming at (reclaim_order) * but kcompactd is woken to compact for the original * request (alloc_order). */ trace_mm_vmscan_kswapd_wake(pgdat->node_id, classzone_idx, alloc_order); reclaim_order = balance_pgdat(pgdat, alloc_order, classzone_idx); if (reclaim_order < alloc_order) goto kswapd_try_sleep; alloc_order = reclaim_order = pgdat->kswapd_order; classzone_idx = pgdat->kswapd_classzone_idx; } tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); current->reclaim_state = NULL; lockdep_clear_current_reclaim_state(); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman9035.16%821.05%
Andrew Morton5421.09%718.42%
Linus Torvalds (pre-git)2810.94%513.16%
Johannes Weiner166.25%12.63%
David Rientjes145.47%12.63%
Rusty Russell93.52%25.26%
Nicholas Piggin83.12%12.63%
Rafael J. Wysocki72.73%25.26%
Takamori Yamaguchi62.34%12.63%
Alex Shi51.95%25.26%
Ingo Molnar51.95%12.63%
Linus Torvalds41.56%12.63%
Motohiro Kosaki31.17%25.26%
Vlastimil Babka20.78%12.63%
Christoph Lameter20.78%12.63%
Mike Travis20.78%12.63%
Jie Liu10.39%12.63%
Total256100.00%38100.00%

/* * A zone is low on free memory, so wake its kswapd task to service it. */
void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) { pg_data_t *pgdat; int z; if (!managed_zone(zone)) return; if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) return; pgdat = zone->zone_pgdat; pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, classzone_idx); pgdat->kswapd_order = max(pgdat->kswapd_order, order); if (!waitqueue_active(&pgdat->kswapd_wait)) return; /* Only wake kswapd if all zones are unbalanced */ for (z = 0; z <= classzone_idx; z++) { zone = pgdat->node_zones + z; if (!managed_zone(zone)) continue; if (zone_balanced(zone, order, classzone_idx)) return; } trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); wake_up_interruptible(&pgdat->kswapd_wait); }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman10164.33%746.67%
Andrew Morton3019.11%213.33%
Nicholas Piggin148.92%16.67%
Con Kolivas53.18%213.33%
Vladimir Davydov31.91%16.67%
Paul Jackson31.91%16.67%
Johannes Weiner10.64%16.67%
Total157100.00%15100.00%

#ifdef CONFIG_HIBERNATION /* * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of * freed pages. * * Rather than trying to age LRUs the aim is to preserve the overall * LRU order by reclaiming preferentially * inactive > active > active referenced > active mapped */
unsigned long shrink_all_memory(unsigned long nr_to_reclaim) { struct reclaim_state reclaim_state; struct scan_control sc = { .nr_to_reclaim = nr_to_reclaim, .gfp_mask = GFP_HIGHUSER_MOVABLE, .reclaim_idx = MAX_NR_ZONES - 1, .priority = DEF_PRIORITY, .may_writepage = 1, .may_unmap = 1, .may_swap = 1, .hibernation_mode = 1, }; struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); struct task_struct *p = current; unsigned long nr_reclaimed; p->flags |= PF_MEMALLOC; lockdep_set_current_reclaim_state(sc.gfp_mask); reclaim_state.reclaimed_slab = 0; p->reclaim_state = &reclaim_state; nr_reclaimed = do_try_to_free_pages(zonelist, &sc); p->reclaim_state = NULL; lockdep_clear_current_reclaim_state(); p->flags &= ~PF_MEMALLOC; return nr_reclaimed; }

Contributors

PersonTokensPropCommitsCommitProp
Rafael J. Wysocki6545.45%112.50%
Motohiro Kosaki5135.66%112.50%
Johannes Weiner128.39%225.00%
Mel Gorman74.90%112.50%
Konstantin Khlebnikov32.10%112.50%
MinChan Kim32.10%112.50%
Andrew Morton21.40%112.50%
Total143100.00%8100.00%

#endif /* CONFIG_HIBERNATION */ /* It's optimal to keep kswapds on the same CPUs as their memory, but not required for correctness. So if the last cpu in a node goes away, we get changed to run anywhere: as the first one comes back, restore their cpu bindings. */
static int kswapd_cpu_online(unsigned int cpu) { int nid; for_each_node_state(nid, N_MEMORY) { pg_data_t *pgdat = NODE_DATA(nid); const struct cpumask *mask; mask = cpumask_of_node(pgdat->node_id); if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) /* One of our CPUs online: restore mask */ set_cpus_allowed_ptr(pgdat->kswapd, mask); } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell4565.22%342.86%
Yasunori Goto1115.94%114.29%
Mike Travis811.59%114.29%
Sebastian Andrzej Siewior45.80%114.29%
Lai Jiangshan11.45%114.29%
Total69100.00%7100.00%

/* * This kswapd start function will be called by init and node-hot-add. * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. */
int kswapd_run(int nid) { pg_data_t *pgdat = NODE_DATA(nid); int ret = 0; if (pgdat->kswapd) return 0; pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); if (IS_ERR(pgdat->kswapd)) { /* failure at boot is fatal */ BUG_ON(system_state == SYSTEM_BOOTING); pr_err("Failed to start kswapd on node %d\n", nid); ret = PTR_ERR(pgdat->kswapd); pgdat->kswapd = NULL; } return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Yasunori Goto5055.56%111.11%
Andrew Morton1314.44%333.33%
Linus Torvalds (pre-git)1011.11%111.11%
Xishi Qiu66.67%111.11%
Gavin Shan66.67%111.11%
Wen Congyang33.33%111.11%
Rusty Russell22.22%111.11%
Total90100.00%9100.00%

/* * Called by memory hotplug when all memory in a node is offlined. Caller must * hold mem_hotplug_begin/end(). */
void kswapd_stop(int nid) { struct task_struct *kswapd = NODE_DATA(nid)->kswapd; if (kswapd) { kthread_stop(kswapd); NODE_DATA(nid)->kswapd = NULL; } }

Contributors

PersonTokensPropCommitsCommitProp
David Rientjes2972.50%150.00%
Jiang Liu1127.50%150.00%
Total40100.00%2100.00%


static int __init kswapd_init(void) { int nid, ret; swap_setup(); for_each_node_state(nid, N_MEMORY) kswapd_run(nid); ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "mm/vmscan:online", kswapd_cpu_online, NULL); WARN_ON(ret < 0); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Yasunori Goto1733.33%112.50%
Sebastian Andrzej Siewior1733.33%112.50%
Andrew Morton59.80%225.00%
Rusty Russell59.80%112.50%
Linus Torvalds (pre-git)47.84%112.50%
Christoph Lameter23.92%112.50%
Lai Jiangshan11.96%112.50%
Total51100.00%8100.00%

module_init(kswapd_init) #ifdef CONFIG_NUMA /* * Node reclaim mode * * If non-zero call node_reclaim when the number of free pages falls below * the watermarks. */ int node_reclaim_mode __read_mostly; #define RECLAIM_OFF 0 #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ #define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */ /* * Priority for NODE_RECLAIM. This determines the fraction of pages * of a node considered for each zone_reclaim. 4 scans 1/16th of * a zone. */ #define NODE_RECLAIM_PRIORITY 4 /* * Percentage of pages in a zone that must be unmapped for node_reclaim to * occur. */ int sysctl_min_unmapped_ratio = 1; /* * If the number of slab pages in a zone grows beyond this percentage then * slab reclaim needs to occur. */ int sysctl_min_slab_ratio = 5;
static inline unsigned long node_unmapped_file_pages(struct pglist_data *pgdat) { unsigned long file_mapped = node_page_state(pgdat, NR_FILE_MAPPED); unsigned long file_lru = node_page_state(pgdat, NR_INACTIVE_FILE) + node_page_state(pgdat, NR_ACTIVE_FILE); /* * It's possible for there to be more file mapped pages than * accounted for by the pages on the file LRU lists because * tmpfs pages accounted for as ANON can also be FILE_MAPPED */ return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman58100.00%4100.00%
Total58100.00%4100.00%

/* Work out how many page cache pages we can reclaim in this reclaim_mode */
static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat) { unsigned long nr_pagecache_reclaimable; unsigned long delta = 0; /* * If RECLAIM_UNMAP is set, then all file pages are considered * potentially reclaimable. Otherwise, we have to worry about * pages like swapcache and node_unmapped_file_pages() provides * a better estimate */ if (node_reclaim_mode & RECLAIM_UNMAP) nr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES); else nr_pagecache_reclaimable = node_unmapped_file_pages(pgdat); /* If we can't clean pages, remove dirty pages from consideration */ if (!(node_reclaim_mode & RECLAIM_WRITE)) delta += node_page_state(pgdat, NR_FILE_DIRTY); /* Watch for any possible underflows due to delta */ if (unlikely(delta > nr_pagecache_reclaimable)) delta = nr_pagecache_reclaimable; return nr_pagecache_reclaimable - delta; }

Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman8095.24%360.00%
Alexandru Moise33.57%120.00%
Zhihui Zhang11.19%120.00%
Total84100.00%5100.00%

/* * Try to free up some pages from this node through reclaim. */
static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) { /* Minimum pages needed in order to stay on node */ const unsigned long nr_pages = 1 << order; struct task_struct *p = current; struct reclaim_state reclaim_state; int classzone_idx = gfp_zone(gfp_mask); struct scan_control sc = { .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), .order = order, .priority = NODE_RECLAIM_PRIORITY, .may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE), .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP), .may_swap = 1, .reclaim_idx = classzone_idx, }; cond_resched(); /* * We need to be able to allocate from the reserves for RECLAIM_UNMAP * and we also need to be able to write out pages for RECLAIM_WRITE * and RECLAIM_UNMAP. */ p->flags |= PF_MEMALLOC | PF_SWAPWRITE; lockdep_set_current_reclaim_state(gfp_mask); reclaim_state.reclaimed_slab = 0; p->reclaim_state = &reclaim_state; if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) { /* * Free memory by calling shrink zone with increasing * priorities until we have enough memory freed. */ do { shrink_node(pgdat, &sc); } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0); } p->reclaim_state = NULL; current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); lockdep_clear_current_reclaim_state(); return sc.nr_reclaimed >= nr_pages; }

Contributors

PersonTokensPropCommitsCommitProp
Christoph Lameter10548.84%836.36%
Johannes Weiner2712.56%29.09%
Mel Gorman2411.16%29.09%
Andrew Morton2310.70%313.64%
Konstantin Khlebnikov115.12%14.55%
Motohiro Kosaki104.65%29.09%
Ming Lei73.26%14.55%
Rik Van Riel41.86%14.55%
Rafael J. Wysocki20.93%14.55%
Zhihui Zhang20.93%14.55%
Total215100.00%22100.00%


int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order) { int ret; /* * Node reclaim reclaims unmapped file backed pages and * slab pages if we are over the defined limits. * * A small portion of unmapped file backed pages is needed for * file I/O otherwise pages read by file I/O will be immediately * thrown out if the node is overallocated. So we do not reclaim * if less than a specified percentage of the node is used by * unmapped file backed pages. */ if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages && sum_zone_node_page_state(pgdat->node_id, NR_SLAB_RECLAIMABLE) <= pgdat->min_slab_pages) return NODE_RECLAIM_FULL; if (!pgdat_reclaimable(pgdat)) return NODE_RECLAIM_FULL; /* * Do not scan if the allocation should not be delayed. */ if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC)) return NODE_RECLAIM_NOSCAN; /* * Only run node reclaim on the local node or on nodes that do not * have associated processors. This will favor the local processor * over remote processors and spread off node memory allocations * as wide as possible. */ if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id()) return NODE_RECLAIM_NOSCAN; if (test_and_set_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags)) return NODE_RECLAIM_NOSCAN; ret = __node_reclaim(pgdat, gfp_mask, order); clear_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags); if (!ret) count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew Morton5738.00%18.33%
Mel Gorman4328.67%433.33%
David Rientjes2214.67%18.33%
Christoph Lameter1510.00%433.33%
Johannes Weiner106.67%18.33%
Lisa Du32.00%18.33%
Total150100.00%12100.00%

#endif /* * page_evictable - test whether a page is evictable * @page: the page to test * * Test whether page is evictable--i.e., should be placed on active/inactive * lists vs unevictable list. * * Reasons page might not be evictable: * (1) page's mapping marked unevictable * (2) page is part of an mlocked VMA * */
int page_evictable(struct page *page) { return !mapping_unevictable(page_mapping(page)) && !PageMlocked(page); }

Contributors

PersonTokensPropCommitsCommitProp
Lee Schermerhorn1869.23%250.00%
Nicholas Piggin415.38%125.00%
Hugh Dickins415.38%125.00%
Total26100.00%4100.00%

#ifdef CONFIG_SHMEM /** * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list * @pages: array of pages to check * @nr_pages: number of pages to check * * Checks pages for evictability and moves them to the appropriate lru list. * * This function is only used for SysV IPC SHM_UNLOCK. */
void check_move_unevictable_pages(struct page **pages, int nr_pages) { struct lruvec *lruvec; struct pglist_data *pgdat = NULL; int pgscanned = 0; int pgrescued = 0; int i; for (i = 0; i < nr_pages; i++) { struct page *page = pages[i]; struct pglist_data *pagepgdat = page_pgdat(page); pgscanned++; if (pagepgdat != pgdat) { if (pgdat) spin_unlock_irq(&pgdat->lru_lock); pgdat = pagepgdat; spin_lock_irq(&pgdat->lru_lock); } lruvec = mem_cgroup_page_lruvec(page, pgdat); if (!PageLRU(page) || !PageUnevictable(page)) continue; if (page_evictable(page)) { enum lru_list lru = page_lru_base_type(page); VM_BUG_ON_PAGE(PageActive(page), page); ClearPageUnevictable(page); del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE); add_page_to_lru_list(page, lruvec, lru); pgrescued++; } } if (pgdat) { __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued); __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned); spin_unlock_irq(&pgdat->lru_lock); } }

Contributors

PersonTokensPropCommitsCommitProp
Hugh Dickins9443.72%342.86%
Lee Schermerhorn8539.53%114.29%
Mel Gorman2813.02%114.29%
Johannes Weiner52.33%114.29%
Sasha Levin31.40%114.29%
Total215100.00%7100.00%

#endif /* CONFIG_SHMEM */

Overall Contributors

PersonTokensPropCommitsCommitProp
Mel Gorman327026.76%8815.47%
Johannes Weiner143211.72%498.61%
Andrew Morton129910.63%8114.24%
Rik Van Riel4813.94%172.99%
Michal Hocko4703.85%172.99%
Motohiro Kosaki4583.75%244.22%
Christoph Lameter4523.70%234.04%
Hugh Dickins4463.65%193.34%
MinChan Kim3152.58%142.46%
Vladimir Davydov3112.54%162.81%
Nicholas Piggin2912.38%152.64%
Lee Schermerhorn2802.29%61.05%
Konstantin Khlebnikov2281.87%162.81%
Fengguang Wu2001.64%81.41%
Balbir Singh1761.44%40.70%
Glauber de Oliveira Costa1431.17%10.18%
Linus Torvalds1431.17%223.87%
Andy Whitcroft1361.11%20.35%
Dave Chinner1210.99%71.23%
Kamezawa Hiroyuki1150.94%81.41%
Linus Torvalds (pre-git)1030.84%122.11%
Vlastimil Babka950.78%81.41%
Rafael J. Wysocki820.67%61.05%
Yasunori Goto820.67%20.35%
Tejun Heo730.60%30.53%
Rusty Russell730.60%50.88%
David Rientjes670.55%30.53%
Kirill A. Shutemov550.45%50.88%
David Shaohua Li540.44%10.18%
Lisa Du540.44%10.18%
Andrea Arcangeli510.42%20.35%
Ying Han470.38%50.88%
Jerome Marchand460.38%20.35%
Anton Vorontsov410.34%10.18%
Shaohua Li410.34%30.53%
Suleiman Souhlal390.32%10.18%
Neil Brown380.31%10.18%
Zlatko Calusic300.25%10.18%
Martin Hicks270.22%10.18%
Sasha Levin270.22%10.18%
Greg Thelen220.18%10.18%
Sebastian Andrzej Siewior210.17%10.18%
Hillf Danton170.14%20.35%
Weijie Yang160.13%10.18%
Paul Jackson160.13%30.53%
Ming Lei140.11%10.18%
Ingo Molnar140.11%30.53%
Jiang Liu110.09%10.18%
Christoph Hellwig110.09%40.70%
Mitchel Humpherys110.09%10.18%
Arnaldo Carvalho de Melo110.09%10.18%
Ross Zwisler100.08%10.18%
Mike Travis100.08%10.18%
Hirofumi Ogawa100.08%10.18%
Keika Kobayashi90.07%10.18%
Con Kolivas90.07%20.35%
Rafael Aquini80.07%10.18%
Andrey Vagin70.06%10.18%
Jaewon Kim70.06%10.18%
Xishi Qiu60.05%10.18%
Gavin Shan60.05%10.18%
Takamori Yamaguchi60.05%10.18%
Jamie Liu60.05%10.18%
Aaditya Kumar60.05%10.18%
Nishanth Aravamudan50.04%10.18%
Alex Shi50.04%20.35%
Zhihui Zhang50.04%10.18%
Nigel Cunningham40.03%20.35%
JoonSoo Kim40.03%20.35%
Aneesh Kumar K.V40.03%10.18%
Dave Hansen40.03%20.35%
Alexandru Moise30.02%10.18%
Wen Congyang30.02%10.18%
David Howells30.02%10.18%
Lai Jiangshan20.02%10.18%
Jens Axboe20.02%20.35%
Richard Henderson20.02%10.18%
Yaowei Bai20.02%10.18%
Pavel Machek20.02%10.18%
Guillaume Chazarain20.02%10.18%
Al Viro20.02%20.35%
Wanpeng Li10.01%10.18%
Zhang Yanfei10.01%10.18%
Bernardo Innocenti10.01%10.18%
Fernando Luis Vázquez Cao10.01%10.18%
Pintu Kumar10.01%10.18%
Tao Ma10.01%10.18%
Michael S. Tsirkin10.01%10.18%
Harvey Harrison10.01%10.18%
Shantanu Goel10.01%10.18%
Jie Liu10.01%10.18%
Zach Brown10.01%10.18%
Wang Sheng-Hui10.01%10.18%
Total12222100.00%569100.00%
Directory: mm
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with cregit.