| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Jérôme Glisse | 3503 | 32.48% | 8 | 3.57% |
| Christoph Lameter | 1537 | 14.25% | 19 | 8.48% |
| Mel Gorman | 1095 | 10.15% | 32 | 14.29% |
| Naoya Horiguchi | 770 | 7.14% | 18 | 8.04% |
| MinChan Kim | 690 | 6.40% | 5 | 2.23% |
| Hugh Dickins | 454 | 4.21% | 19 | 8.48% |
| Brice Goglin | 437 | 4.05% | 5 | 2.23% |
| Michal Hocko | 413 | 3.83% | 4 | 1.79% |
| Peter Zijlstra | 229 | 2.12% | 3 | 1.34% |
| Dave Hansen | 204 | 1.89% | 1 | 0.45% |
| Dominik Brodowski | 203 | 1.88% | 1 | 0.45% |
| Kirill A. Shutemov | 185 | 1.72% | 12 | 5.36% |
| Zi Yan | 134 | 1.24% | 1 | 0.45% |
| Nicholas Piggin | 82 | 0.76% | 5 | 2.23% |
| JoonSoo Kim | 70 | 0.65% | 4 | 1.79% |
| Matthew Wilcox | 57 | 0.53% | 2 | 0.89% |
| Rafael Aquini | 54 | 0.50% | 3 | 1.34% |
| Linus Torvalds | 48 | 0.45% | 4 | 1.79% |
| David Rientjes | 44 | 0.41% | 2 | 0.89% |
| Andrea Arcangeli | 43 | 0.40% | 8 | 3.57% |
| Motohiro Kosaki | 42 | 0.39% | 4 | 1.79% |
| Aneesh Kumar K.V | 41 | 0.38% | 2 | 0.89% |
| Vlastimil Babka | 35 | 0.32% | 5 | 2.23% |
| H. Peter Anvin | 33 | 0.31% | 1 | 0.45% |
| Vladimir Davydov | 27 | 0.25% | 1 | 0.45% |
| Johannes Weiner | 26 | 0.24% | 5 | 2.23% |
| Shaohua Li | 25 | 0.23% | 3 | 1.34% |
| Lin Ming | 23 | 0.21% | 1 | 0.45% |
| Rik Van Riel | 21 | 0.19% | 1 | 0.45% |
| Geert Uytterhoeven | 21 | 0.19% | 1 | 0.45% |
| Kamezawa Hiroyuki | 19 | 0.18% | 3 | 1.34% |
| David P. Quigley | 16 | 0.15% | 1 | 0.45% |
| David Howells | 15 | 0.14% | 3 | 1.34% |
| Cyrill V. Gorcunov | 14 | 0.13% | 1 | 0.45% |
| Sasha Levin | 14 | 0.13% | 2 | 0.89% |
| Tony Lu | 14 | 0.13% | 1 | 0.45% |
| Gleb Natapov | 12 | 0.11% | 1 | 0.45% |
| Nick Desaulniers | 12 | 0.11% | 1 | 0.45% |
| Benjamin LaHaise | 12 | 0.11% | 1 | 0.45% |
| Wanpeng Li | 11 | 0.10% | 1 | 0.45% |
| Richard Weinberger | 10 | 0.09% | 1 | 0.45% |
| Andi Kleen | 8 | 0.07% | 2 | 0.89% |
| Will Deacon | 6 | 0.06% | 1 | 0.45% |
| Lee Schermerhorn | 6 | 0.06% | 2 | 0.89% |
| Konstantin Khlebnikov | 6 | 0.06% | 1 | 0.45% |
| Anshuman Khandual | 6 | 0.06% | 1 | 0.45% |
| Dave Jiang | 5 | 0.05% | 1 | 0.45% |
| Mark Hairgrove | 5 | 0.05% | 1 | 0.45% |
| Rabin Vincent | 5 | 0.05% | 1 | 0.45% |
| Greg Thelen | 4 | 0.04% | 1 | 0.45% |
| Jacobo Giralt | 4 | 0.04% | 1 | 0.45% |
| Yisheng Xie | 4 | 0.04% | 1 | 0.45% |
| Tejun Heo | 3 | 0.03% | 1 | 0.45% |
| Pavel Emelyanov | 3 | 0.03% | 1 | 0.45% |
| Eric W. Biedermann | 3 | 0.03% | 1 | 0.45% |
| Ralph Campbell | 3 | 0.03% | 1 | 0.45% |
| Ingo Molnar | 3 | 0.03% | 1 | 0.45% |
| Adrian Bunk | 3 | 0.03% | 1 | 0.45% |
| Michal Nazarewicz | 3 | 0.03% | 1 | 0.45% |
| Hillf Danton | 2 | 0.02% | 1 | 0.45% |
| Gerald Schaefer | 2 | 0.02% | 1 | 0.45% |
| Jianguo Wu | 1 | 0.01% | 1 | 0.45% |
| Greg Kroah-Hartman | 1 | 0.01% | 1 | 0.45% |
| Stephen Rothwell | 1 | 0.01% | 1 | 0.45% |
| Paul Gortmaker | 1 | 0.01% | 1 | 0.45% |
| Lai Jiangshan | 1 | 0.01% | 1 | 0.45% |
| Wang Sheng-Hui | 1 | 0.01% | 1 | 0.45% |
| Total | 10785 | 224 |
// SPDX-License-Identifier: GPL-2.0 /* * Memory Migration functionality - linux/mm/migrate.c * * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter * * Page migration was first developed in the context of the memory hotplug * project. The main authors of the migration code are: * * IWAMOTO Toshihiro <iwamoto@valinux.co.jp> * Hirokazu Takahashi <taka@valinux.co.jp> * Dave Hansen <haveblue@us.ibm.com> * Christoph Lameter */ #include <linux/migrate.h> #include <linux/export.h> #include <linux/swap.h> #include <linux/swapops.h> #include <linux/pagemap.h> #include <linux/buffer_head.h> #include <linux/mm_inline.h> #include <linux/nsproxy.h> #include <linux/pagevec.h> #include <linux/ksm.h> #include <linux/rmap.h> #include <linux/topology.h> #include <linux/cpu.h> #include <linux/cpuset.h> #include <linux/writeback.h> #include <linux/mempolicy.h> #include <linux/vmalloc.h> #include <linux/security.h> #include <linux/backing-dev.h> #include <linux/compaction.h> #include <linux/syscalls.h> #include <linux/compat.h> #include <linux/hugetlb.h> #include <linux/hugetlb_cgroup.h> #include <linux/gfp.h> #include <linux/pfn_t.h> #include <linux/memremap.h> #include <linux/userfaultfd_k.h> #include <linux/balloon_compaction.h> #include <linux/mmu_notifier.h> #include <linux/page_idle.h> #include <linux/page_owner.h> #include <linux/sched/mm.h> #include <linux/ptrace.h> #include <asm/tlbflush.h> #define CREATE_TRACE_POINTS #include <trace/events/migrate.h> #include "internal.h" /* * migrate_prep() needs to be called before we start compiling a list of pages * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is * undesirable, use migrate_prep_local() */ int migrate_prep(void) { /* * Clear the LRU lists so pages can be isolated. * Note that pages may be moved off the LRU after we have * drained them. Those pages will fail to migrate like other * pages that may be busy. */ lru_add_drain_all(); return 0; } /* Do the necessary work of migrate_prep but not if it involves other CPUs */ int migrate_prep_local(void) { lru_add_drain(); return 0; } int isolate_movable_page(struct page *page, isolate_mode_t mode) { struct address_space *mapping; /* * Avoid burning cycles with pages that are yet under __free_pages(), * or just got freed under us. * * In case we 'win' a race for a movable page being freed under us and * raise its refcount preventing __free_pages() from doing its job * the put_page() at the end of this block will take care of * release this page, thus avoiding a nasty leakage. */ if (unlikely(!get_page_unless_zero(page))) goto out; /* * Check PageMovable before holding a PG_lock because page's owner * assumes anybody doesn't touch PG_lock of newly allocated page * so unconditionally grapping the lock ruins page's owner side. */ if (unlikely(!__PageMovable(page))) goto out_putpage; /* * As movable pages are not isolated from LRU lists, concurrent * compaction threads can race against page migration functions * as well as race against the releasing a page. * * In order to avoid having an already isolated movable page * being (wrongly) re-isolated while it is under migration, * or to avoid attempting to isolate pages being released, * lets be sure we have the page lock * before proceeding with the movable page isolation steps. */ if (unlikely(!trylock_page(page))) goto out_putpage; if (!PageMovable(page) || PageIsolated(page)) goto out_no_isolated; mapping = page_mapping(page); VM_BUG_ON_PAGE(!mapping, page); if (!mapping->a_ops->isolate_page(page, mode)) goto out_no_isolated; /* Driver shouldn't use PG_isolated bit of page->flags */ WARN_ON_ONCE(PageIsolated(page)); __SetPageIsolated(page); unlock_page(page); return 0; out_no_isolated: unlock_page(page); out_putpage: put_page(page); out: return -EBUSY; } /* It should be called on page which is PG_movable */ void putback_movable_page(struct page *page) { struct address_space *mapping; VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageMovable(page), page); VM_BUG_ON_PAGE(!PageIsolated(page), page); mapping = page_mapping(page); mapping->a_ops->putback_page(page); __ClearPageIsolated(page); } /* * Put previously isolated pages back onto the appropriate lists * from where they were once taken off for compaction/migration. * * This function shall be used whenever the isolated pageset has been * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range() * and isolate_huge_page(). */ void putback_movable_pages(struct list_head *l) { struct page *page; struct page *page2; list_for_each_entry_safe(page, page2, l, lru) { if (unlikely(PageHuge(page))) { putback_active_hugepage(page); continue; } list_del(&page->lru); /* * We isolated non-lru movable page so here we can use * __PageMovable because LRU page's mapping cannot have * PAGE_MAPPING_MOVABLE. */ if (unlikely(__PageMovable(page))) { VM_BUG_ON_PAGE(!PageIsolated(page), page); lock_page(page); if (PageMovable(page)) putback_movable_page(page); else __ClearPageIsolated(page); unlock_page(page); put_page(page); } else { mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_is_file_cache(page), -hpage_nr_pages(page)); putback_lru_page(page); } } } /* * Restore a potential migration pte to a working pte entry */ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, unsigned long addr, void *old) { struct page_vma_mapped_walk pvmw = { .page = old, .vma = vma, .address = addr, .flags = PVMW_SYNC | PVMW_MIGRATION, }; struct page *new; pte_t pte; swp_entry_t entry; VM_BUG_ON_PAGE(PageTail(page), page); while (page_vma_mapped_walk(&pvmw)) { if (PageKsm(page)) new = page; else new = page - pvmw.page->index + linear_page_index(vma, pvmw.address); #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION /* PMD-mapped THP migration entry */ if (!pvmw.pte) { VM_BUG_ON_PAGE(PageHuge(page) || !PageTransCompound(page), page); remove_migration_pmd(&pvmw, new); continue; } #endif get_page(new); pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot))); if (pte_swp_soft_dirty(*pvmw.pte)) pte = pte_mksoft_dirty(pte); /* * Recheck VMA as permissions can change since migration started */ entry = pte_to_swp_entry(*pvmw.pte); if (is_write_migration_entry(entry)) pte = maybe_mkwrite(pte, vma); if (unlikely(is_zone_device_page(new))) { if (is_device_private_page(new)) { entry = make_device_private_entry(new, pte_write(pte)); pte = swp_entry_to_pte(entry); } else if (is_device_public_page(new)) { pte = pte_mkdevmap(pte); flush_dcache_page(new); } } else flush_dcache_page(new); #ifdef CONFIG_HUGETLB_PAGE if (PageHuge(new)) { pte = pte_mkhuge(pte); pte = arch_make_huge_pte(pte, vma, new, 0); set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); if (PageAnon(new)) hugepage_add_anon_rmap(new, vma, pvmw.address); else page_dup_rmap(new, true); } else #endif { set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); if (PageAnon(new)) page_add_anon_rmap(new, vma, pvmw.address, false); else page_add_file_rmap(new, false); } if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new)) mlock_vma_page(new); if (PageTransHuge(page) && PageMlocked(page)) clear_page_mlock(page); /* No need to invalidate - it was non-present before */ update_mmu_cache(vma, pvmw.address, pvmw.pte); } return true; } /* * Get rid of all migration entries and replace them by * references to the indicated page. */ void remove_migration_ptes(struct page *old, struct page *new, bool locked) { struct rmap_walk_control rwc = { .rmap_one = remove_migration_pte, .arg = old, }; if (locked) rmap_walk_locked(new, &rwc); else rmap_walk(new, &rwc); } /* * Something used the pte of a page under migration. We need to * get to the page and wait until migration is finished. * When we return from this function the fault will be retried. */ void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, spinlock_t *ptl) { pte_t pte; swp_entry_t entry; struct page *page; spin_lock(ptl); pte = *ptep; if (!is_swap_pte(pte)) goto out; entry = pte_to_swp_entry(pte); if (!is_migration_entry(entry)) goto out; page = migration_entry_to_page(entry); /* * Once page cache replacement of page migration started, page_count * *must* be zero. And, we don't want to call wait_on_page_locked() * against a page without get_page(). * So, we use get_page_unless_zero(), here. Even failed, page fault * will occur again. */ if (!get_page_unless_zero(page)) goto out; pte_unmap_unlock(ptep, ptl); wait_on_page_locked(page); put_page(page); return; out: pte_unmap_unlock(ptep, ptl); } void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, unsigned long address) { spinlock_t *ptl = pte_lockptr(mm, pmd); pte_t *ptep = pte_offset_map(pmd, address); __migration_entry_wait(mm, ptep, ptl); } void migration_entry_wait_huge(struct vm_area_struct *vma, struct mm_struct *mm, pte_t *pte) { spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte); __migration_entry_wait(mm, pte, ptl); } #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd) { spinlock_t *ptl; struct page *page; ptl = pmd_lock(mm, pmd); if (!is_pmd_migration_entry(*pmd)) goto unlock; page = migration_entry_to_page(pmd_to_swp_entry(*pmd)); if (!get_page_unless_zero(page)) goto unlock; spin_unlock(ptl); wait_on_page_locked(page); put_page(page); return; unlock: spin_unlock(ptl); } #endif #ifdef CONFIG_BLOCK /* Returns true if all buffers are successfully locked */ static bool buffer_migrate_lock_buffers(struct buffer_head *head, enum migrate_mode mode) { struct buffer_head *bh = head; /* Simple case, sync compaction */ if (mode != MIGRATE_ASYNC) { do { get_bh(bh); lock_buffer(bh); bh = bh->b_this_page; } while (bh != head); return true; } /* async case, we cannot block on lock_buffer so use trylock_buffer */ do { get_bh(bh); if (!trylock_buffer(bh)) { /* * We failed to lock the buffer and cannot stall in * async migration. Release the taken locks */ struct buffer_head *failed_bh = bh; put_bh(failed_bh); bh = head; while (bh != failed_bh) { unlock_buffer(bh); put_bh(bh); bh = bh->b_this_page; } return false; } bh = bh->b_this_page; } while (bh != head); return true; } #else static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, enum migrate_mode mode) { return true; } #endif /* CONFIG_BLOCK */ /* * Replace the page in the mapping. * * The number of remaining references must be: * 1 for anonymous pages without a mapping * 2 for pages with a mapping * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. */ int migrate_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page, struct buffer_head *head, enum migrate_mode mode, int extra_count) { XA_STATE(xas, &mapping->i_pages, page_index(page)); struct zone *oldzone, *newzone; int dirty; int expected_count = 1 + extra_count; /* * Device public or private pages have an extra refcount as they are * ZONE_DEVICE pages. */ expected_count += is_device_private_page(page); expected_count += is_device_public_page(page); if (!mapping) { /* Anonymous page without mapping */ if (page_count(page) != expected_count) return -EAGAIN; /* No turning back from here */ newpage->index = page->index; newpage->mapping = page->mapping; if (PageSwapBacked(page)) __SetPageSwapBacked(newpage); return MIGRATEPAGE_SUCCESS; } oldzone = page_zone(page); newzone = page_zone(newpage); xas_lock_irq(&xas); expected_count += hpage_nr_pages(page) + page_has_private(page); if (page_count(page) != expected_count || xas_load(&xas) != page) { xas_unlock_irq(&xas); return -EAGAIN; } if (!page_ref_freeze(page, expected_count)) { xas_unlock_irq(&xas); return -EAGAIN; } /* * In the async migration case of moving a page with buffers, lock the * buffers using trylock before the mapping is moved. If the mapping * was moved, we later failed to lock the buffers and could not move * the mapping back due to an elevated page count, we would have to * block waiting on other references to be dropped. */ if (mode == MIGRATE_ASYNC && head && !buffer_migrate_lock_buffers(head, mode)) { page_ref_unfreeze(page, expected_count); xas_unlock_irq(&xas); return -EAGAIN; } /* * Now we know that no one else is looking at the page: * no turning back from here. */ newpage->index = page->index; newpage->mapping = page->mapping; page_ref_add(newpage, hpage_nr_pages(page)); /* add cache reference */ if (PageSwapBacked(page)) { __SetPageSwapBacked(newpage); if (PageSwapCache(page)) { SetPageSwapCache(newpage); set_page_private(newpage, page_private(page)); } } else { VM_BUG_ON_PAGE(PageSwapCache(page), page); } /* Move dirty while page refs frozen and newpage not yet exposed */ dirty = PageDirty(page); if (dirty) { ClearPageDirty(page); SetPageDirty(newpage); } xas_store(&xas, newpage); if (PageTransHuge(page)) { int i; for (i = 1; i < HPAGE_PMD_NR; i++) { xas_next(&xas); xas_store(&xas, newpage + i); } } /* * Drop cache reference from old page by unfreezing * to one less reference. * We know this isn't the last reference. */ page_ref_unfreeze(page, expected_count - hpage_nr_pages(page)); xas_unlock(&xas); /* Leave irq disabled to prevent preemption while updating stats */ /* * If moved to a different zone then also account * the page for that zone. Other VM counters will be * taken care of when we establish references to the * new page and drop references to the old page. * * Note that anonymous pages are accounted for * via NR_FILE_PAGES and NR_ANON_MAPPED if they * are mapped to swap space. */ if (newzone != oldzone) { __dec_node_state(oldzone->zone_pgdat, NR_FILE_PAGES); __inc_node_state(newzone->zone_pgdat, NR_FILE_PAGES); if (PageSwapBacked(page) && !PageSwapCache(page)) { __dec_node_state(oldzone->zone_pgdat, NR_SHMEM); __inc_node_state(newzone->zone_pgdat, NR_SHMEM); } if (dirty && mapping_cap_account_dirty(mapping)) { __dec_node_state(oldzone->zone_pgdat, NR_FILE_DIRTY); __dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING); __inc_node_state(newzone->zone_pgdat, NR_FILE_DIRTY); __inc_zone_state(newzone, NR_ZONE_WRITE_PENDING); } } local_irq_enable(); return MIGRATEPAGE_SUCCESS; } EXPORT_SYMBOL(migrate_page_move_mapping); /* * The expected number of remaining references is the same as that * of migrate_page_move_mapping(). */ int migrate_huge_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page) { XA_STATE(xas, &mapping->i_pages, page_index(page)); int expected_count; xas_lock_irq(&xas); expected_count = 2 + page_has_private(page); if (page_count(page) != expected_count || xas_load(&xas) != page) { xas_unlock_irq(&xas); return -EAGAIN; } if (!page_ref_freeze(page, expected_count)) { xas_unlock_irq(&xas); return -EAGAIN; } newpage->index = page->index; newpage->mapping = page->mapping; get_page(newpage); xas_store(&xas, newpage); page_ref_unfreeze(page, expected_count - 1); xas_unlock_irq(&xas); return MIGRATEPAGE_SUCCESS; } /* * Gigantic pages are so large that we do not guarantee that page++ pointer * arithmetic will work across the entire page. We need something more * specialized. */ static void __copy_gigantic_page(struct page *dst, struct page *src, int nr_pages) { int i; struct page *dst_base = dst; struct page *src_base = src; for (i = 0; i < nr_pages; ) { cond_resched(); copy_highpage(dst, src); i++; dst = mem_map_next(dst, dst_base, i); src = mem_map_next(src, src_base, i); } } static void copy_huge_page(struct page *dst, struct page *src) { int i; int nr_pages; if (PageHuge(src)) { /* hugetlbfs page */ struct hstate *h = page_hstate(src); nr_pages = pages_per_huge_page(h); if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) { __copy_gigantic_page(dst, src, nr_pages); return; } } else { /* thp page */ BUG_ON(!PageTransHuge(src)); nr_pages = hpage_nr_pages(src); } for (i = 0; i < nr_pages; i++) { cond_resched(); copy_highpage(dst + i, src + i); } } /* * Copy the page to its new location */ void migrate_page_states(struct page *newpage, struct page *page) { int cpupid; if (PageError(page)) SetPageError(newpage); if (PageReferenced(page)) SetPageReferenced(newpage); if (PageUptodate(page)) SetPageUptodate(newpage); if (TestClearPageActive(page)) { VM_BUG_ON_PAGE(PageUnevictable(page), page); SetPageActive(newpage); } else if (TestClearPageUnevictable(page)) SetPageUnevictable(newpage); if (PageWorkingset(page)) SetPageWorkingset(newpage); if (PageChecked(page)) SetPageChecked(newpage); if (PageMappedToDisk(page)) SetPageMappedToDisk(newpage); /* Move dirty on pages not done by migrate_page_move_mapping() */ if (PageDirty(page)) SetPageDirty(newpage); if (page_is_young(page)) set_page_young(newpage); if (page_is_idle(page)) set_page_idle(newpage); /* * Copy NUMA information to the new page, to prevent over-eager * future migrations of this same page. */ cpupid = page_cpupid_xchg_last(page, -1); page_cpupid_xchg_last(newpage, cpupid); ksm_migrate_page(newpage, page); /* * Please do not reorder this without considering how mm/ksm.c's * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). */ if (PageSwapCache(page)) ClearPageSwapCache(page); ClearPagePrivate(page); set_page_private(page, 0); /* * If any waiters have accumulated on the new page then * wake them up. */ if (PageWriteback(newpage)) end_page_writeback(newpage); copy_page_owner(page, newpage); mem_cgroup_migrate(page, newpage); } EXPORT_SYMBOL(migrate_page_states); void migrate_page_copy(struct page *newpage, struct page *page) { if (PageHuge(page) || PageTransHuge(page)) copy_huge_page(newpage, page); else copy_highpage(newpage, page); migrate_page_states(newpage, page); } EXPORT_SYMBOL(migrate_page_copy); /************************************************************ * Migration functions ***********************************************************/ /* * Common logic to directly migrate a single LRU page suitable for * pages that do not use PagePrivate/PagePrivate2. * * Pages are locked upon entry and exit. */ int migrate_page(struct address_space *mapping, struct page *newpage, struct page *page, enum migrate_mode mode) { int rc; BUG_ON(PageWriteback(page)); /* Writeback must be complete */ rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); if (rc != MIGRATEPAGE_SUCCESS) return rc; if (mode != MIGRATE_SYNC_NO_COPY) migrate_page_copy(newpage, page); else migrate_page_states(newpage, page); return MIGRATEPAGE_SUCCESS; } EXPORT_SYMBOL(migrate_page); #ifdef CONFIG_BLOCK /* * Migration function for pages with buffers. This function can only be used * if the underlying filesystem guarantees that no other references to "page" * exist. */ int buffer_migrate_page(struct address_space *mapping, struct page *newpage, struct page *page, enum migrate_mode mode) { struct buffer_head *bh, *head; int rc; if (!page_has_buffers(page)) return migrate_page(mapping, newpage, page, mode); head = page_buffers(page); rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0); if (rc != MIGRATEPAGE_SUCCESS) return rc; /* * In the async case, migrate_page_move_mapping locked the buffers * with an IRQ-safe spinlock held. In the sync case, the buffers * need to be locked now */ if (mode != MIGRATE_ASYNC) BUG_ON(!buffer_migrate_lock_buffers(head, mode)); ClearPagePrivate(page); set_page_private(newpage, page_private(page)); set_page_private(page, 0); put_page(page); get_page(newpage); bh = head; do { set_bh_page(bh, newpage, bh_offset(bh)); bh = bh->b_this_page; } while (bh != head); SetPagePrivate(newpage); if (mode != MIGRATE_SYNC_NO_COPY) migrate_page_copy(newpage, page); else migrate_page_states(newpage, page); bh = head; do { unlock_buffer(bh); put_bh(bh); bh = bh->b_this_page; } while (bh != head); return MIGRATEPAGE_SUCCESS; } EXPORT_SYMBOL(buffer_migrate_page); #endif /* * Writeback a page to clean the dirty state */ static int writeout(struct address_space *mapping, struct page *page) { struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, .nr_to_write = 1, .range_start = 0, .range_end = LLONG_MAX, .for_reclaim = 1 }; int rc; if (!mapping->a_ops->writepage) /* No write method for the address space */ return -EINVAL; if (!clear_page_dirty_for_io(page)) /* Someone else already triggered a write */ return -EAGAIN; /* * A dirty page may imply that the underlying filesystem has * the page on some queue. So the page must be clean for * migration. Writeout may mean we loose the lock and the * page state is no longer what we checked for earlier. * At this point we know that the migration attempt cannot * be successful. */ remove_migration_ptes(page, page, false); rc = mapping->a_ops->writepage(page, &wbc); if (rc != AOP_WRITEPAGE_ACTIVATE) /* unlocked. Relock */ lock_page(page); return (rc < 0) ? -EIO : -EAGAIN; } /* * Default handling if a filesystem does not provide a migration function. */ static int fallback_migrate_page(struct address_space *mapping, struct page *newpage, struct page *page, enum migrate_mode mode) { if (PageDirty(page)) { /* Only writeback pages in full synchronous migration */ switch (mode) { case MIGRATE_SYNC: case MIGRATE_SYNC_NO_COPY: break; default: return -EBUSY; } return writeout(mapping, page); } /* * Buffers may be managed in a filesystem specific way. * We must have no buffers or drop them. */ if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) return -EAGAIN; return migrate_page(mapping, newpage, page, mode); } /* * Move a page to a newly allocated page * The page is locked and all ptes have been successfully removed. * * The new page will have replaced the old page if this function * is successful. * * Return value: * < 0 - error code * MIGRATEPAGE_SUCCESS - success */ static int move_to_new_page(struct page *newpage, struct page *page, enum migrate_mode mode) { struct address_space *mapping; int rc = -EAGAIN; bool is_lru = !__PageMovable(page); VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); mapping = page_mapping(page); if (likely(is_lru)) { if (!mapping) rc = migrate_page(mapping, newpage, page, mode); else if (mapping->a_ops->migratepage) /* * Most pages have a mapping and most filesystems * provide a migratepage callback. Anonymous pages * are part of swap space which also has its own * migratepage callback. This is the most common path * for page migration. */ rc = mapping->a_ops->migratepage(mapping, newpage, page, mode); else rc = fallback_migrate_page(mapping, newpage, page, mode); } else { /* * In case of non-lru page, it could be released after * isolation step. In that case, we shouldn't try migration. */ VM_BUG_ON_PAGE(!PageIsolated(page), page); if (!PageMovable(page)) { rc = MIGRATEPAGE_SUCCESS; __ClearPageIsolated(page); goto out; } rc = mapping->a_ops->migratepage(mapping, newpage, page, mode); WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS && !PageIsolated(page)); } /* * When successful, old pagecache page->mapping must be cleared before * page is freed; but stats require that PageAnon be left as PageAnon. */ if (rc == MIGRATEPAGE_SUCCESS) { if (__PageMovable(page)) { VM_BUG_ON_PAGE(!PageIsolated(page), page); /* * We clear PG_movable under page_lock so any compactor * cannot try to migrate this page. */ __ClearPageIsolated(page); } /* * Anonymous and movable page->mapping will be cleard by * free_pages_prepare so don't reset it here for keeping * the type to work PageAnon, for example. */ if (!PageMappingFlags(page)) page->mapping = NULL; } out: return rc; } static int __unmap_and_move(struct page *page, struct page *newpage, int force, enum migrate_mode mode) { int rc = -EAGAIN; int page_was_mapped = 0; struct anon_vma *anon_vma = NULL; bool is_lru = !__PageMovable(page); if (!trylock_page(page)) { if (!force || mode == MIGRATE_ASYNC) goto out; /* * It's not safe for direct compaction to call lock_page. * For example, during page readahead pages are added locked * to the LRU. Later, when the IO completes the pages are * marked uptodate and unlocked. However, the queueing * could be merging multiple pages for one bio (e.g. * mpage_readpages). If an allocation happens for the * second or third page, the process can end up locking * the same page twice and deadlocking. Rather than * trying to be clever about what pages can be locked, * avoid the use of lock_page for direct compaction * altogether. */ if (current->flags & PF_MEMALLOC) goto out; lock_page(page); } if (PageWriteback(page)) { /* * Only in the case of a full synchronous migration is it * necessary to wait for PageWriteback. In the async case, * the retry loop is too short and in the sync-light case, * the overhead of stalling is too much */ switch (mode) { case MIGRATE_SYNC: case MIGRATE_SYNC_NO_COPY: break; default: rc = -EBUSY; goto out_unlock; } if (!force) goto out_unlock; wait_on_page_writeback(page); } /* * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, * we cannot notice that anon_vma is freed while we migrates a page. * This get_anon_vma() delays freeing anon_vma pointer until the end * of migration. File cache pages are no problem because of page_lock() * File Caches may use write_page() or lock_page() in migration, then, * just care Anon page here. * * Only page_get_anon_vma() understands the subtleties of * getting a hold on an anon_vma from outside one of its mms. * But if we cannot get anon_vma, then we won't need it anyway, * because that implies that the anon page is no longer mapped * (and cannot be remapped so long as we hold the page lock). */ if (PageAnon(page) && !PageKsm(page)) anon_vma = page_get_anon_vma(page); /* * Block others from accessing the new page when we get around to * establishing additional references. We are usually the only one * holding a reference to newpage at this point. We used to have a BUG * here if trylock_page(newpage) fails, but would like to allow for * cases where there might be a race with the previous use of newpage. * This is much like races on refcount of oldpage: just don't BUG(). */ if (unlikely(!trylock_page(newpage))) goto out_unlock; if (unlikely(!is_lru)) { rc = move_to_new_page(newpage, page, mode); goto out_unlock_both; } /* * Corner case handling: * 1. When a new swap-cache page is read into, it is added to the LRU * and treated as swapcache but it has no rmap yet. * Calling try_to_unmap() against a page->mapping==NULL page will * trigger a BUG. So handle it here. * 2. An orphaned page (see truncate_complete_page) might have * fs-private metadata. The page can be picked up due to memory * offlining. Everywhere else except page reclaim, the page is * invisible to the vm, so the page can not be migrated. So try to * free the metadata, so the page can be freed. */ if (!page->mapping) { VM_BUG_ON_PAGE(PageAnon(page), page); if (page_has_private(page)) { try_to_free_buffers(page); goto out_unlock_both; } } else if (page_mapped(page)) { /* Establish migration ptes */ VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma, page); try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); page_was_mapped = 1; } if (!page_mapped(page)) rc = move_to_new_page(newpage, page, mode); if (page_was_mapped) remove_migration_ptes(page, rc == MIGRATEPAGE_SUCCESS ? newpage : page, false); out_unlock_both: unlock_page(newpage); out_unlock: /* Drop an anon_vma reference if we took one */ if (anon_vma) put_anon_vma(anon_vma); unlock_page(page); out: /* * If migration is successful, decrease refcount of the newpage * which will not free the page because new page owner increased * refcounter. As well, if it is LRU page, add the page to LRU * list in here. */ if (rc == MIGRATEPAGE_SUCCESS) { if (unlikely(__PageMovable(newpage))) put_page(newpage); else putback_lru_page(newpage); } return rc; } /* * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work * around it. */ #if defined(CONFIG_ARM) && \ defined(GCC_VERSION) && GCC_VERSION < 40900 && GCC_VERSION >= 40700 #define ICE_noinline noinline #else #define ICE_noinline #endif /* * Obtain the lock on page, remove all ptes and migrate the page * to the newly allocated page in newpage. */ static ICE_noinline int unmap_and_move(new_page_t get_new_page, free_page_t put_new_page, unsigned long private, struct page *page, int force, enum migrate_mode mode, enum migrate_reason reason) { int rc = MIGRATEPAGE_SUCCESS; struct page *newpage; if (!thp_migration_supported() && PageTransHuge(page)) return -ENOMEM; newpage = get_new_page(page, private); if (!newpage) return -ENOMEM; if (page_count(page) == 1) { /* page was freed from under us. So we are done. */ ClearPageActive(page); ClearPageUnevictable(page); if (unlikely(__PageMovable(page))) { lock_page(page); if (!PageMovable(page)) __ClearPageIsolated(page); unlock_page(page); } if (put_new_page) put_new_page(newpage, private); else put_page(newpage); goto out; } rc = __unmap_and_move(page, newpage, force, mode); if (rc == MIGRATEPAGE_SUCCESS) set_page_owner_migrate_reason(newpage, reason); out: if (rc != -EAGAIN) { /* * A page that has been migrated has all references * removed and will be freed. A page that has not been * migrated will have kepts its references and be * restored. */ list_del(&page->lru); /* * Compaction can migrate also non-LRU pages which are * not accounted to NR_ISOLATED_*. They can be recognized * as __PageMovable */ if (likely(!__PageMovable(page))) mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_is_file_cache(page), -hpage_nr_pages(page)); } /* * If migration is successful, releases reference grabbed during * isolation. Otherwise, restore the page to right list unless * we want to retry. */ if (rc == MIGRATEPAGE_SUCCESS) { put_page(page); if (reason == MR_MEMORY_FAILURE) { /* * Set PG_HWPoison on just freed page * intentionally. Although it's rather weird, * it's how HWPoison flag works at the moment. */ if (set_hwpoison_free_buddy_page(page)) num_poisoned_pages_inc(); } } else { if (rc != -EAGAIN) { if (likely(!__PageMovable(page))) { putback_lru_page(page); goto put_new; } lock_page(page); if (PageMovable(page)) putback_movable_page(page); else __ClearPageIsolated(page); unlock_page(page); put_page(page); } put_new: if (put_new_page) put_new_page(newpage, private); else put_page(newpage); } return rc; } /* * Counterpart of unmap_and_move_page() for hugepage migration. * * This function doesn't wait the completion of hugepage I/O * because there is no race between I/O and migration for hugepage. * Note that currently hugepage I/O occurs only in direct I/O * where no lock is held and PG_writeback is irrelevant, * and writeback status of all subpages are counted in the reference * count of the head page (i.e. if all subpages of a 2MB hugepage are * under direct I/O, the reference of the head page is 512 and a bit more.) * This means that when we try to migrate hugepage whose subpages are * doing direct I/O, some references remain after try_to_unmap() and * hugepage migration fails without data corruption. * * There is also no race when direct I/O is issued on the page under migration, * because then pte is replaced with migration swap entry and direct I/O code * will wait in the page fault for migration to complete. */ static int unmap_and_move_huge_page(new_page_t get_new_page, free_page_t put_new_page, unsigned long private, struct page *hpage, int force, enum migrate_mode mode, int reason) { int rc = -EAGAIN; int page_was_mapped = 0; struct page *new_hpage; struct anon_vma *anon_vma = NULL; /* * Movability of hugepages depends on architectures and hugepage size. * This check is necessary because some callers of hugepage migration * like soft offline and memory hotremove don't walk through page * tables or check whether the hugepage is pmd-based or not before * kicking migration. */ if (!hugepage_migration_supported(page_hstate(hpage))) { putback_active_hugepage(hpage); return -ENOSYS; } new_hpage = get_new_page(hpage, private); if (!new_hpage) return -ENOMEM; if (!trylock_page(hpage)) { if (!force) goto out; switch (mode) { case MIGRATE_SYNC: case MIGRATE_SYNC_NO_COPY: break; default: goto out; } lock_page(hpage); } if (PageAnon(hpage)) anon_vma = page_get_anon_vma(hpage); if (unlikely(!trylock_page(new_hpage))) goto put_anon; if (page_mapped(hpage)) { try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); page_was_mapped = 1; } if (!page_mapped(hpage)) rc = move_to_new_page(new_hpage, hpage, mode); if (page_was_mapped) remove_migration_ptes(hpage, rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false); unlock_page(new_hpage); put_anon: if (anon_vma) put_anon_vma(anon_vma); if (rc == MIGRATEPAGE_SUCCESS) { move_hugetlb_state(hpage, new_hpage, reason); put_new_page = NULL; } unlock_page(hpage); out: if (rc != -EAGAIN) putback_active_hugepage(hpage); /* * If migration was not successful and there's a freeing callback, use * it. Otherwise, put_page() will drop the reference grabbed during * isolation. */ if (put_new_page) put_new_page(new_hpage, private); else putback_active_hugepage(new_hpage); return rc; } /* * migrate_pages - migrate the pages specified in a list, to the free pages * supplied as the target for the page migration * * @from: The list of pages to be migrated. * @get_new_page: The function used to allocate free pages to be used * as the target of the page migration. * @put_new_page: The function used to free target pages if migration * fails, or NULL if no special handling is necessary. * @private: Private data to be passed on to get_new_page() * @mode: The migration mode that specifies the constraints for * page migration, if any. * @reason: The reason for page migration. * * The function returns after 10 attempts or if no pages are movable any more * because the list has become empty or no retryable pages exist any more. * The caller should call putback_movable_pages() to return pages to the LRU * or free list only if ret != 0. * * Returns the number of pages that were not migrated, or an error code. */ int migrate_pages(struct list_head *from, new_page_t get_new_page, free_page_t put_new_page, unsigned long private, enum migrate_mode mode, int reason) { int retry = 1; int nr_failed = 0; int nr_succeeded = 0; int pass = 0; struct page *page; struct page *page2; int swapwrite = current->flags & PF_SWAPWRITE; int rc; if (!swapwrite) current->flags |= PF_SWAPWRITE; for(pass = 0; pass < 10 && retry; pass++) { retry = 0; list_for_each_entry_safe(page, page2, from, lru) { retry: cond_resched(); if (PageHuge(page)) rc = unmap_and_move_huge_page(get_new_page, put_new_page, private, page, pass > 2, mode, reason); else rc = unmap_and_move(get_new_page, put_new_page, private, page, pass > 2, mode, reason); switch(rc) { case -ENOMEM: /* * THP migration might be unsupported or the * allocation could've failed so we should * retry on the same page with the THP split * to base pages. * * Head page is retried immediately and tail * pages are added to the tail of the list so * we encounter them after the rest of the list * is processed. */ if (PageTransHuge(page) && !PageHuge(page)) { lock_page(page); rc = split_huge_page_to_list(page, from); unlock_page(page); if (!rc) { list_safe_reset_next(page, page2, lru); goto retry; } } nr_failed++; goto out; case -EAGAIN: retry++; break; case MIGRATEPAGE_SUCCESS: nr_succeeded++; break; default: /* * Permanent failure (-EBUSY, -ENOSYS, etc.): * unlike -EAGAIN case, the failed page is * removed from migration page list and not * retried in the next outer loop. */ nr_failed++; break; } } } nr_failed += retry; rc = nr_failed; out: if (nr_succeeded) count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); if (nr_failed) count_vm_events(PGMIGRATE_FAIL, nr_failed); trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason); if (!swapwrite) current->flags &= ~PF_SWAPWRITE; return rc; } #ifdef CONFIG_NUMA static int store_status(int __user *status, int start, int value, int nr) { while (nr-- > 0) { if (put_user(value, status + start)) return -EFAULT; start++; } return 0; } static int do_move_pages_to_node(struct mm_struct *mm, struct list_head *pagelist, int node) { int err; if (list_empty(pagelist)) return 0; err = migrate_pages(pagelist, alloc_new_node_page, NULL, node, MIGRATE_SYNC, MR_SYSCALL); if (err) putback_movable_pages(pagelist); return err; } /* * Resolves the given address to a struct page, isolates it from the LRU and * puts it to the given pagelist. * Returns -errno if the page cannot be found/isolated or 0 when it has been * queued or the page doesn't need to be migrated because it is already on * the target node */ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, int node, struct list_head *pagelist, bool migrate_all) { struct vm_area_struct *vma; struct page *page; unsigned int follflags; int err; down_read(&mm->mmap_sem); err = -EFAULT; vma = find_vma(mm, addr); if (!vma || addr < vma->vm_start || !vma_migratable(vma)) goto out; /* FOLL_DUMP to ignore special (like zero) pages */ follflags = FOLL_GET | FOLL_DUMP; page = follow_page(vma, addr, follflags); err = PTR_ERR(page); if (IS_ERR(page)) goto out; err = -ENOENT; if (!page) goto out; err = 0; if (page_to_nid(page) == node) goto out_putpage; err = -EACCES; if (page_mapcount(page) > 1 && !migrate_all) goto out_putpage; if (PageHuge(page)) { if (PageHead(page)) { isolate_huge_page(page, pagelist); err = 0; } } else { struct page *head; head = compound_head(page); err = isolate_lru_page(head); if (err) goto out_putpage; err = 0; list_add_tail(&head->lru, pagelist); mod_node_page_state(page_pgdat(head), NR_ISOLATED_ANON + page_is_file_cache(head), hpage_nr_pages(head)); } out_putpage: /* * Either remove the duplicate refcount from * isolate_lru_page() or drop the page ref if it was * not isolated. */ put_page(page); out: up_read(&mm->mmap_sem); return err; } /* * Migrate an array of page address onto an array of nodes and fill * the corresponding array of status. */ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, unsigned long nr_pages, const void __user * __user *pages, const int __user *nodes, int __user *status, int flags) { int current_node = NUMA_NO_NODE; LIST_HEAD(pagelist); int start, i; int err = 0, err1; migrate_prep(); for (i = start = 0; i < nr_pages; i++) { const void __user *p; unsigned long addr; int node; err = -EFAULT; if (get_user(p, pages + i)) goto out_flush; if (get_user(node, nodes + i)) goto out_flush; addr = (unsigned long)p; err = -ENODEV; if (node < 0 || node >= MAX_NUMNODES) goto out_flush; if (!node_state(node, N_MEMORY)) goto out_flush; err = -EACCES; if (!node_isset(node, task_nodes)) goto out_flush; if (current_node == NUMA_NO_NODE) { current_node = node; start = i; } else if (node != current_node) { err = do_move_pages_to_node(mm, &pagelist, current_node); if (err) goto out; err = store_status(status, start, current_node, i - start); if (err) goto out; start = i; current_node = node; } /* * Errors in the page lookup or isolation are not fatal and we simply * report them via status */ err = add_page_for_migration(mm, addr, current_node, &pagelist, flags & MPOL_MF_MOVE_ALL); if (!err) continue; err = store_status(status, i, err, 1); if (err) goto out_flush; err = do_move_pages_to_node(mm, &pagelist, current_node); if (err) goto out; if (i > start) { err = store_status(status, start, current_node, i - start); if (err) goto out; } current_node = NUMA_NO_NODE; } out_flush: if (list_empty(&pagelist)) return err; /* Make sure we do not overwrite the existing error */ err1 = do_move_pages_to_node(mm, &pagelist, current_node); if (!err1) err1 = store_status(status, start, current_node, i - start); if (!err) err = err1; out: return err; } /* * Determine the nodes of an array of pages and store it in an array of status. */ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, const void __user **pages, int *status) { unsigned long i; down_read(&mm->mmap_sem); for (i = 0; i < nr_pages; i++) { unsigned long addr = (unsigned long)(*pages); struct vm_area_struct *vma; struct page *page; int err = -EFAULT; vma = find_vma(mm, addr); if (!vma || addr < vma->vm_start) goto set_status; /* FOLL_DUMP to ignore special (like zero) pages */ page = follow_page(vma, addr, FOLL_DUMP); err = PTR_ERR(page); if (IS_ERR(page)) goto set_status; err = page ? page_to_nid(page) : -ENOENT; set_status: *status = err; pages++; status++; } up_read(&mm->mmap_sem); } /* * Determine the nodes of a user array of pages and store it in * a user array of status. */ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, const void __user * __user *pages, int __user *status) { #define DO_PAGES_STAT_CHUNK_NR 16 const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; int chunk_status[DO_PAGES_STAT_CHUNK_NR]; while (nr_pages) { unsigned long chunk_nr; chunk_nr = nr_pages; if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) chunk_nr = DO_PAGES_STAT_CHUNK_NR; if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) break; do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) break; pages += chunk_nr; status += chunk_nr; nr_pages -= chunk_nr; } return nr_pages ? -EFAULT : 0; } /* * Move a list of pages in the address space of the currently executing * process. */ static int kernel_move_pages(pid_t pid, unsigned long nr_pages, const void __user * __user *pages, const int __user *nodes, int __user *status, int flags) { struct task_struct *task; struct mm_struct *mm; int err; nodemask_t task_nodes; /* Check flags */ if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) return -EINVAL; if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) return -EPERM; /* Find the mm_struct */ rcu_read_lock(); task = pid ? find_task_by_vpid(pid) : current; if (!task) { rcu_read_unlock(); return -ESRCH; } get_task_struct(task); /* * Check if this process has the right to modify the specified * process. Use the regular "ptrace_may_access()" checks. */ if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { rcu_read_unlock(); err = -EPERM; goto out; } rcu_read_unlock(); err = security_task_movememory(task); if (err) goto out; task_nodes = cpuset_mems_allowed(task); mm = get_task_mm(task); put_task_struct(task); if (!mm) return -EINVAL; if (nodes) err = do_pages_move(mm, task_nodes, nr_pages, pages, nodes, status, flags); else err = do_pages_stat(mm, nr_pages, pages, status); mmput(mm); return err; out: put_task_struct(task); return err; } SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, const void __user * __user *, pages, const int __user *, nodes, int __user *, status, int, flags) { return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags); } #ifdef CONFIG_COMPAT COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages, compat_uptr_t __user *, pages32, const int __user *, nodes, int __user *, status, int, flags) { const void __user * __user *pages; int i; pages = compat_alloc_user_space(nr_pages * sizeof(void *)); for (i = 0; i < nr_pages; i++) { compat_uptr_t p; if (get_user(p, pages32 + i) || put_user(compat_ptr(p), pages + i)) return -EFAULT; } return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags); } #endif /* CONFIG_COMPAT */ #ifdef CONFIG_NUMA_BALANCING /* * Returns true if this is a safe migration target node for misplaced NUMA * pages. Currently it only checks the watermarks which crude */ static bool migrate_balanced_pgdat(struct pglist_data *pgdat, unsigned long nr_migrate_pages) { int z; for (z = pgdat->nr_zones - 1; z >= 0; z--) { struct zone *zone = pgdat->node_zones + z; if (!populated_zone(zone)) continue; /* Avoid waking kswapd by allocating pages_to_migrate pages. */ if (!zone_watermark_ok(zone, 0, high_wmark_pages(zone) + nr_migrate_pages, 0, 0)) continue; return true; } return false; } static struct page *alloc_misplaced_dst_page(struct page *page, unsigned long data) { int nid = (int) data; struct page *newpage; newpage = __alloc_pages_node(nid, (GFP_HIGHUSER_MOVABLE | __GFP_THISNODE | __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN) & ~__GFP_RECLAIM, 0); return newpage; } static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) { int page_lru; VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page); /* Avoid migrating to a node that is nearly full */ if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) return 0; if (isolate_lru_page(page)) return 0; /* * migrate_misplaced_transhuge_page() skips page migration's usual * check on page_count(), so we must do it here, now that the page * has been isolated: a GUP pin, or any other pin, prevents migration. * The expected page count is 3: 1 for page's mapcount and 1 for the * caller's pin and 1 for the reference taken by isolate_lru_page(). */ if (PageTransHuge(page) && page_count(page) != 3) { putback_lru_page(page); return 0; } page_lru = page_is_file_cache(page); mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru, hpage_nr_pages(page)); /* * Isolating the page has taken another reference, so the * caller's reference can be safely dropped without the page * disappearing underneath us during migration. */ put_page(page); return 1; } bool pmd_trans_migrating(pmd_t pmd) { struct page *page = pmd_page(pmd); return PageLocked(page); } /* * Attempt to migrate a misplaced page to the specified destination * node. Caller is expected to have an elevated reference count on * the page that will be dropped by this function before returning. */ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, int node) { pg_data_t *pgdat = NODE_DATA(node); int isolated; int nr_remaining; LIST_HEAD(migratepages); /* * Don't migrate file pages that are mapped in multiple processes * with execute permissions as they are probably shared libraries. */ if (page_mapcount(page) != 1 && page_is_file_cache(page) && (vma->vm_flags & VM_EXEC)) goto out; /* * Also do not migrate dirty pages as not all filesystems can move * dirty pages in MIGRATE_ASYNC mode which is a waste of cycles. */ if (page_is_file_cache(page) && PageDirty(page)) goto out; isolated = numamigrate_isolate_page(pgdat, page); if (!isolated) goto out; list_add(&page->lru, &migratepages); nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page, NULL, node, MIGRATE_ASYNC, MR_NUMA_MISPLACED); if (nr_remaining) { if (!list_empty(&migratepages)) { list_del(&page->lru); dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); putback_lru_page(page); } isolated = 0; } else count_vm_numa_event(NUMA_PAGE_MIGRATE); BUG_ON(!list_empty(&migratepages)); return isolated; out: put_page(page); return 0; } #endif /* CONFIG_NUMA_BALANCING */ #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) /* * Migrates a THP to a given target node. page must be locked and is unlocked * before returning. */ int migrate_misplaced_transhuge_page(struct mm_struct *mm, struct vm_area_struct *vma, pmd_t *pmd, pmd_t entry, unsigned long address, struct page *page, int node) { spinlock_t *ptl; pg_data_t *pgdat = NODE_DATA(node); int isolated = 0; struct page *new_page = NULL; int page_lru = page_is_file_cache(page); unsigned long start = address & HPAGE_PMD_MASK; new_page = alloc_pages_node(node, (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), HPAGE_PMD_ORDER); if (!new_page) goto out_fail; prep_transhuge_page(new_page); isolated = numamigrate_isolate_page(pgdat, page); if (!isolated) { put_page(new_page); goto out_fail; } /* Prepare a page as a migration target */ __SetPageLocked(new_page); if (PageSwapBacked(page)) __SetPageSwapBacked(new_page); /* anon mapping, we can simply copy page->mapping to the new page: */ new_page->mapping = page->mapping; new_page->index = page->index; /* flush the cache before copying using the kernel virtual address */ flush_cache_range(vma, start, start + HPAGE_PMD_SIZE); migrate_page_copy(new_page, page); WARN_ON(PageLRU(new_page)); /* Recheck the target PMD */ ptl = pmd_lock(mm, pmd); if (unlikely(!pmd_same(*pmd, entry) || !page_ref_freeze(page, 2))) { spin_unlock(ptl); /* Reverse changes made by migrate_page_copy() */ if (TestClearPageActive(new_page)) SetPageActive(page); if (TestClearPageUnevictable(new_page)) SetPageUnevictable(page); unlock_page(new_page); put_page(new_page); /* Free it */ /* Retake the callers reference and putback on LRU */ get_page(page); putback_lru_page(page); mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); goto out_unlock; } entry = mk_huge_pmd(new_page, vma->vm_page_prot); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); /* * Overwrite the old entry under pagetable lock and establish * the new PTE. Any parallel GUP will either observe the old * page blocking on the page lock, block on the page table * lock or observe the new page. The SetPageUptodate on the * new page and page_add_new_anon_rmap guarantee the copy is * visible before the pagetable update. */ page_add_anon_rmap(new_page, vma, start, true); /* * At this point the pmd is numa/protnone (i.e. non present) and the TLB * has already been flushed globally. So no TLB can be currently * caching this non present pmd mapping. There's no need to clear the * pmd before doing set_pmd_at(), nor to flush the TLB after * set_pmd_at(). Clearing the pmd here would introduce a race * condition against MADV_DONTNEED, because MADV_DONTNEED only holds the * mmap_sem for reading. If the pmd is set to NULL at any given time, * MADV_DONTNEED won't wait on the pmd lock and it'll skip clearing this * pmd. */ set_pmd_at(mm, start, pmd, entry); update_mmu_cache_pmd(vma, address, &entry); page_ref_unfreeze(page, 2); mlock_migrate_page(new_page, page); page_remove_rmap(page, true); set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED); spin_unlock(ptl); /* Take an "isolate" reference and put new page on the LRU. */ get_page(new_page); putback_lru_page(new_page); unlock_page(new_page); unlock_page(page); put_page(page); /* Drop the rmap reference */ put_page(page); /* Drop the LRU isolation reference */ count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); return isolated; out_fail: count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); ptl = pmd_lock(mm, pmd); if (pmd_same(*pmd, entry)) { entry = pmd_modify(entry, vma->vm_page_prot); set_pmd_at(mm, start, pmd, entry); update_mmu_cache_pmd(vma, address, &entry); } spin_unlock(ptl); out_unlock: unlock_page(page); put_page(page); return 0; } #endif /* CONFIG_NUMA_BALANCING */ #endif /* CONFIG_NUMA */ #if defined(CONFIG_MIGRATE_VMA_HELPER) struct migrate_vma { struct vm_area_struct *vma; unsigned long *dst; unsigned long *src; unsigned long cpages; unsigned long npages; unsigned long start; unsigned long end; }; static int migrate_vma_collect_hole(unsigned long start, unsigned long end, struct mm_walk *walk) { struct migrate_vma *migrate = walk->private; unsigned long addr; for (addr = start & PAGE_MASK; addr < end; addr += PAGE_SIZE) { migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE; migrate->dst[migrate->npages] = 0; migrate->npages++; migrate->cpages++; } return 0; } static int migrate_vma_collect_skip(unsigned long start, unsigned long end, struct mm_walk *walk) { struct migrate_vma *migrate = walk->private; unsigned long addr; for (addr = start & PAGE_MASK; addr < end; addr += PAGE_SIZE) { migrate->dst[migrate->npages] = 0; migrate->src[migrate->npages++] = 0; } return 0; } static int migrate_vma_collect_pmd(pmd_t *pmdp, unsigned long start, unsigned long end, struct mm_walk *walk) { struct migrate_vma *migrate = walk->private; struct vm_area_struct *vma = walk->vma; struct mm_struct *mm = vma->vm_mm; unsigned long addr = start, unmapped = 0; spinlock_t *ptl; pte_t *ptep; again: if (pmd_none(*pmdp)) return migrate_vma_collect_hole(start, end, walk); if (pmd_trans_huge(*pmdp)) { struct page *page; ptl = pmd_lock(mm, pmdp); if (unlikely(!pmd_trans_huge(*pmdp))) { spin_unlock(ptl); goto again; } page = pmd_page(*pmdp); if (is_huge_zero_page(page)) { spin_unlock(ptl); split_huge_pmd(vma, pmdp, addr); if (pmd_trans_unstable(pmdp)) return migrate_vma_collect_skip(start, end, walk); } else { int ret; get_page(page); spin_unlock(ptl); if (unlikely(!trylock_page(page))) return migrate_vma_collect_skip(start, end, walk); ret = split_huge_page(page); unlock_page(page); put_page(page); if (ret) return migrate_vma_collect_skip(start, end, walk); if (pmd_none(*pmdp)) return migrate_vma_collect_hole(start, end, walk); } } if (unlikely(pmd_bad(*pmdp))) return migrate_vma_collect_skip(start, end, walk); ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); arch_enter_lazy_mmu_mode(); for (; addr < end; addr += PAGE_SIZE, ptep++) { unsigned long mpfn, pfn; struct page *page; swp_entry_t entry; pte_t pte; pte = *ptep; pfn = pte_pfn(pte); if (pte_none(pte)) { mpfn = MIGRATE_PFN_MIGRATE; migrate->cpages++; pfn = 0; goto next; } if (!pte_present(pte)) { mpfn = pfn = 0; /* * Only care about unaddressable device page special * page table entry. Other special swap entries are not * migratable, and we ignore regular swapped page. */ entry = pte_to_swp_entry(pte); if (!is_device_private_entry(entry)) goto next; page = device_private_entry_to_page(entry); mpfn = migrate_pfn(page_to_pfn(page))| MIGRATE_PFN_DEVICE | MIGRATE_PFN_MIGRATE; if (is_write_device_private_entry(entry)) mpfn |= MIGRATE_PFN_WRITE; } else { if (is_zero_pfn(pfn)) { mpfn = MIGRATE_PFN_MIGRATE; migrate->cpages++; pfn = 0; goto next; } page = _vm_normal_page(migrate->vma, addr, pte, true); mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE; mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; } /* FIXME support THP */ if (!page || !page->mapping || PageTransCompound(page)) { mpfn = pfn = 0; goto next; } pfn = page_to_pfn(page); /* * By getting a reference on the page we pin it and that blocks * any kind of migration. Side effect is that it "freezes" the * pte. * * We drop this reference after isolating the page from the lru * for non device page (device page are not on the lru and thus * can't be dropped from it). */ get_page(page); migrate->cpages++; /* * Optimize for the common case where page is only mapped once * in one process. If we can lock the page, then we can safely * set up a special migration page table entry now. */ if (trylock_page(page)) { pte_t swp_pte; mpfn |= MIGRATE_PFN_LOCKED; ptep_get_and_clear(mm, addr, ptep); /* Setup special migration page table entry */ entry = make_migration_entry(page, mpfn & MIGRATE_PFN_WRITE); swp_pte = swp_entry_to_pte(entry); if (pte_soft_dirty(pte)) swp_pte = pte_swp_mksoft_dirty(swp_pte); set_pte_at(mm, addr, ptep, swp_pte); /* * This is like regular unmap: we remove the rmap and * drop page refcount. Page won't be freed, as we took * a reference just above. */ page_remove_rmap(page, false); put_page(page); if (pte_present(pte)) unmapped++; } next: migrate->dst[migrate->npages] = 0; migrate->src[migrate->npages++] = mpfn; } arch_leave_lazy_mmu_mode(); pte_unmap_unlock(ptep - 1, ptl); /* Only flush the TLB if we actually modified any entries */ if (unmapped) flush_tlb_range(walk->vma, start, end); return 0; } /* * migrate_vma_collect() - collect pages over a range of virtual addresses * @migrate: migrate struct containing all migration information * * This will walk the CPU page table. For each virtual address backed by a * valid page, it updates the src array and takes a reference on the page, in * order to pin the page until we lock it and unmap it. */ static void migrate_vma_collect(struct migrate_vma *migrate) { struct mm_walk mm_walk; mm_walk.pmd_entry = migrate_vma_collect_pmd; mm_walk.pte_entry = NULL; mm_walk.pte_hole = migrate_vma_collect_hole; mm_walk.hugetlb_entry = NULL; mm_walk.test_walk = NULL; mm_walk.vma = migrate->vma; mm_walk.mm = migrate->vma->vm_mm; mm_walk.private = migrate; mmu_notifier_invalidate_range_start(mm_walk.mm, migrate->start, migrate->end); walk_page_range(migrate->start, migrate->end, &mm_walk); mmu_notifier_invalidate_range_end(mm_walk.mm, migrate->start, migrate->end); migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT); } /* * migrate_vma_check_page() - check if page is pinned or not * @page: struct page to check * * Pinned pages cannot be migrated. This is the same test as in * migrate_page_move_mapping(), except that here we allow migration of a * ZONE_DEVICE page. */ static bool migrate_vma_check_page(struct page *page) { /* * One extra ref because caller holds an extra reference, either from * isolate_lru_page() for a regular page, or migrate_vma_collect() for * a device page. */ int extra = 1; /* * FIXME support THP (transparent huge page), it is bit more complex to * check them than regular pages, because they can be mapped with a pmd * or with a pte (split pte mapping). */ if (PageCompound(page)) return false; /* Page from ZONE_DEVICE have one extra reference */ if (is_zone_device_page(page)) { /* * Private page can never be pin as they have no valid pte and * GUP will fail for those. Yet if there is a pending migration * a thread might try to wait on the pte migration entry and * will bump the page reference count. Sadly there is no way to * differentiate a regular pin from migration wait. Hence to * avoid 2 racing thread trying to migrate back to CPU to enter * infinite loop (one stoping migration because the other is * waiting on pte migration entry). We always return true here. * * FIXME proper solution is to rework migration_entry_wait() so * it does not need to take a reference on page. */ if (is_device_private_page(page)) return true; /* * Only allow device public page to be migrated and account for * the extra reference count imply by ZONE_DEVICE pages. */ if (!is_device_public_page(page)) return false; extra++; } /* For file back page */ if (page_mapping(page)) extra += 1 + page_has_private(page); if ((page_count(page) - extra) > page_mapcount(page)) return false; return true; } /* * migrate_vma_prepare() - lock pages and isolate them from the lru * @migrate: migrate struct containing all migration information * * This locks pages that have been collected by migrate_vma_collect(). Once each * page is locked it is isolated from the lru (for non-device pages). Finally, * the ref taken by migrate_vma_collect() is dropped, as locked pages cannot be * migrated by concurrent kernel threads. */ static void migrate_vma_prepare(struct migrate_vma *migrate) { const unsigned long npages = migrate->npages; const unsigned long start = migrate->start; unsigned long addr, i, restore = 0; bool allow_drain = true; lru_add_drain(); for (i = 0; (i < npages) && migrate->cpages; i++) { struct page *page = migrate_pfn_to_page(migrate->src[i]); bool remap = true; if (!page) continue; if (!(migrate->src[i] & MIGRATE_PFN_LOCKED)) { /* * Because we are migrating several pages there can be * a deadlock between 2 concurrent migration where each * are waiting on each other page lock. * * Make migrate_vma() a best effort thing and backoff * for any page we can not lock right away. */ if (!trylock_page(page)) { migrate->src[i] = 0; migrate->cpages--; put_page(page); continue; } remap = false; migrate->src[i] |= MIGRATE_PFN_LOCKED; } /* ZONE_DEVICE pages are not on LRU */ if (!is_zone_device_page(page)) { if (!PageLRU(page) && allow_drain) { /* Drain CPU's pagevec */ lru_add_drain_all(); allow_drain = false; } if (isolate_lru_page(page)) { if (remap) { migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; migrate->cpages--; restore++; } else { migrate->src[i] = 0; unlock_page(page); migrate->cpages--; put_page(page); } continue; } /* Drop the reference we took in collect */ put_page(page); } if (!migrate_vma_check_page(page)) { if (remap) { migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; migrate->cpages--; restore++; if (!is_zone_device_page(page)) { get_page(page); putback_lru_page(page); } } else { migrate->src[i] = 0; unlock_page(page); migrate->cpages--; if (!is_zone_device_page(page)) putback_lru_page(page); else put_page(page); } } } for (i = 0, addr = start; i < npages && restore; i++, addr += PAGE_SIZE) { struct page *page = migrate_pfn_to_page(migrate->src[i]); if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE)) continue; remove_migration_pte(page, migrate->vma, addr, page); migrate->src[i] = 0; unlock_page(page); put_page(page); restore--; } } /* * migrate_vma_unmap() - replace page mapping with special migration pte entry * @migrate: migrate struct containing all migration information * * Replace page mapping (CPU page table pte) with a special migration pte entry * and check again if it has been pinned. Pinned pages are restored because we * cannot migrate them. * * This is the last step before we call the device driver callback to allocate * destination memory and copy contents of original page over to new page. */ static void migrate_vma_unmap(struct migrate_vma *migrate) { int flags = TTU_MIGRATION | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS; const unsigned long npages = migrate->npages; const unsigned long start = migrate->start; unsigned long addr, i, restore = 0; for (i = 0; i < npages; i++) { struct page *page = migrate_pfn_to_page(migrate->src[i]); if (!page || !(migrate->src[i] & MIGRATE_PFN_MIGRATE)) continue; if (page_mapped(page)) { try_to_unmap(page, flags); if (page_mapped(page)) goto restore; } if (migrate_vma_check_page(page)) continue; restore: migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; migrate->cpages--; restore++; } for (addr = start, i = 0; i < npages && restore; addr += PAGE_SIZE, i++) { struct page *page = migrate_pfn_to_page(migrate->src[i]); if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE)) continue; remove_migration_ptes(page, page, false); migrate->src[i] = 0; unlock_page(page); restore--; if (is_zone_device_page(page)) put_page(page); else putback_lru_page(page); } } static void migrate_vma_insert_page(struct migrate_vma *migrate, unsigned long addr, struct page *page, unsigned long *src, unsigned long *dst) { struct vm_area_struct *vma = migrate->vma; struct mm_struct *mm = vma->vm_mm; struct mem_cgroup *memcg; bool flush = false; spinlock_t *ptl; pte_t entry; pgd_t *pgdp; p4d_t *p4dp; pud_t *pudp; pmd_t *pmdp; pte_t *ptep; /* Only allow populating anonymous memory */ if (!vma_is_anonymous(vma)) goto abort; pgdp = pgd_offset(mm, addr); p4dp = p4d_alloc(mm, pgdp, addr); if (!p4dp) goto abort; pudp = pud_alloc(mm, p4dp, addr); if (!pudp) goto abort; pmdp = pmd_alloc(mm, pudp, addr); if (!pmdp) goto abort; if (pmd_trans_huge(*pmdp) || pmd_devmap(*pmdp)) goto abort; /* * Use pte_alloc() instead of pte_alloc_map(). We can't run * pte_offset_map() on pmds where a huge pmd might be created * from a different thread. * * pte_alloc_map() is safe to use under down_write(mmap_sem) or when * parallel threads are excluded by other means. * * Here we only have down_read(mmap_sem). */ if (pte_alloc(mm, pmdp, addr)) goto abort; /* See the comment in pte_alloc_one_map() */ if (unlikely(pmd_trans_unstable(pmdp))) goto abort; if (unlikely(anon_vma_prepare(vma))) goto abort; if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false)) goto abort; /* * The memory barrier inside __SetPageUptodate makes sure that * preceding stores to the page contents become visible before * the set_pte_at() write. */ __SetPageUptodate(page); if (is_zone_device_page(page)) { if (is_device_private_page(page)) { swp_entry_t swp_entry; swp_entry = make_device_private_entry(page, vma->vm_flags & VM_WRITE); entry = swp_entry_to_pte(swp_entry); } else if (is_device_public_page(page)) { entry = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); if (vma->vm_flags & VM_WRITE) entry = pte_mkwrite(pte_mkdirty(entry)); entry = pte_mkdevmap(entry); } } else { entry = mk_pte(page, vma->vm_page_prot); if (vma->vm_flags & VM_WRITE) entry = pte_mkwrite(pte_mkdirty(entry)); } ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); if (pte_present(*ptep)) { unsigned long pfn = pte_pfn(*ptep); if (!is_zero_pfn(pfn)) { pte_unmap_unlock(ptep, ptl); mem_cgroup_cancel_charge(page, memcg, false); goto abort; } flush = true; } else if (!pte_none(*ptep)) { pte_unmap_unlock(ptep, ptl); mem_cgroup_cancel_charge(page, memcg, false); goto abort; } /* * Check for usefaultfd but do not deliver the fault. Instead, * just back off. */ if (userfaultfd_missing(vma)) { pte_unmap_unlock(ptep, ptl); mem_cgroup_cancel_charge(page, memcg, false); goto abort; } inc_mm_counter(mm, MM_ANONPAGES); page_add_new_anon_rmap(page, vma, addr, false); mem_cgroup_commit_charge(page, memcg, false, false); if (!is_zone_device_page(page)) lru_cache_add_active_or_unevictable(page, vma); get_page(page); if (flush) { flush_cache_page(vma, addr, pte_pfn(*ptep)); ptep_clear_flush_notify(vma, addr, ptep); set_pte_at_notify(mm, addr, ptep, entry); update_mmu_cache(vma, addr, ptep); } else { /* No need to invalidate - it was non-present before */ set_pte_at(mm, addr, ptep, entry); update_mmu_cache(vma, addr, ptep); } pte_unmap_unlock(ptep, ptl); *src = MIGRATE_PFN_MIGRATE; return; abort: *src &= ~MIGRATE_PFN_MIGRATE; } /* * migrate_vma_pages() - migrate meta-data from src page to dst page * @migrate: migrate struct containing all migration information * * This migrates struct page meta-data from source struct page to destination * struct page. This effectively finishes the migration from source page to the * destination page. */ static void migrate_vma_pages(struct migrate_vma *migrate) { const unsigned long npages = migrate->npages; const unsigned long start = migrate->start; struct vm_area_struct *vma = migrate->vma; struct mm_struct *mm = vma->vm_mm; unsigned long addr, i, mmu_start; bool notified = false; for (i = 0, addr = start; i < npages; addr += PAGE_SIZE, i++) { struct page *newpage = migrate_pfn_to_page(migrate->dst[i]); struct page *page = migrate_pfn_to_page(migrate->src[i]); struct address_space *mapping; int r; if (!newpage) { migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; continue; } if (!page) { if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE)) { continue; } if (!notified) { mmu_start = addr; notified = true; mmu_notifier_invalidate_range_start(mm, mmu_start, migrate->end); } migrate_vma_insert_page(migrate, addr, newpage, &migrate->src[i], &migrate->dst[i]); continue; } mapping = page_mapping(page); if (is_zone_device_page(newpage)) { if (is_device_private_page(newpage)) { /* * For now only support private anonymous when * migrating to un-addressable device memory. */ if (mapping) { migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; continue; } } else if (!is_device_public_page(newpage)) { /* * Other types of ZONE_DEVICE page are not * supported. */ migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; continue; } } r = migrate_page(mapping, newpage, page, MIGRATE_SYNC_NO_COPY); if (r != MIGRATEPAGE_SUCCESS) migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; } /* * No need to double call mmu_notifier->invalidate_range() callback as * the above ptep_clear_flush_notify() inside migrate_vma_insert_page() * did already call it. */ if (notified) mmu_notifier_invalidate_range_only_end(mm, mmu_start, migrate->end); } /* * migrate_vma_finalize() - restore CPU page table entry * @migrate: migrate struct containing all migration information * * This replaces the special migration pte entry with either a mapping to the * new page if migration was successful for that page, or to the original page * otherwise. * * This also unlocks the pages and puts them back on the lru, or drops the extra * refcount, for device pages. */ static void migrate_vma_finalize(struct migrate_vma *migrate) { const unsigned long npages = migrate->npages; unsigned long i; for (i = 0; i < npages; i++) { struct page *newpage = migrate_pfn_to_page(migrate->dst[i]); struct page *page = migrate_pfn_to_page(migrate->src[i]); if (!page) { if (newpage) { unlock_page(newpage); put_page(newpage); } continue; } if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE) || !newpage) { if (newpage) { unlock_page(newpage); put_page(newpage); } newpage = page; } remove_migration_ptes(page, newpage, false); unlock_page(page); migrate->cpages--; if (is_zone_device_page(page)) put_page(page); else putback_lru_page(page); if (newpage != page) { unlock_page(newpage); if (is_zone_device_page(newpage)) put_page(newpage); else putback_lru_page(newpage); } } } /* * migrate_vma() - migrate a range of memory inside vma * * @ops: migration callback for allocating destination memory and copying * @vma: virtual memory area containing the range to be migrated * @start: start address of the range to migrate (inclusive) * @end: end address of the range to migrate (exclusive) * @src: array of hmm_pfn_t containing source pfns * @dst: array of hmm_pfn_t containing destination pfns * @private: pointer passed back to each of the callback * Returns: 0 on success, error code otherwise * * This function tries to migrate a range of memory virtual address range, using * callbacks to allocate and copy memory from source to destination. First it * collects all the pages backing each virtual address in the range, saving this * inside the src array. Then it locks those pages and unmaps them. Once the pages * are locked and unmapped, it checks whether each page is pinned or not. Pages * that aren't pinned have the MIGRATE_PFN_MIGRATE flag set (by this function) * in the corresponding src array entry. It then restores any pages that are * pinned, by remapping and unlocking those pages. * * At this point it calls the alloc_and_copy() callback. For documentation on * what is expected from that callback, see struct migrate_vma_ops comments in * include/linux/migrate.h * * After the alloc_and_copy() callback, this function goes over each entry in * the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag * set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set, * then the function tries to migrate struct page information from the source * struct page to the destination struct page. If it fails to migrate the struct * page information, then it clears the MIGRATE_PFN_MIGRATE flag in the src * array. * * At this point all successfully migrated pages have an entry in the src * array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst * array entry with MIGRATE_PFN_VALID flag set. * * It then calls the finalize_and_map() callback. See comments for "struct * migrate_vma_ops", in include/linux/migrate.h for details about * finalize_and_map() behavior. * * After the finalize_and_map() callback, for successfully migrated pages, this * function updates the CPU page table to point to new pages, otherwise it * restores the CPU page table to point to the original source pages. * * Function returns 0 after the above steps, even if no pages were migrated * (The function only returns an error if any of the arguments are invalid.) * * Both src and dst array must be big enough for (end - start) >> PAGE_SHIFT * unsigned long entries. */ int migrate_vma(const struct migrate_vma_ops *ops, struct vm_area_struct *vma, unsigned long start, unsigned long end, unsigned long *src, unsigned long *dst, void *private) { struct migrate_vma migrate; /* Sanity check the arguments */ start &= PAGE_MASK; end &= PAGE_MASK; if (!vma || is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL) || vma_is_dax(vma)) return -EINVAL; if (start < vma->vm_start || start >= vma->vm_end) return -EINVAL; if (end <= vma->vm_start || end > vma->vm_end) return -EINVAL; if (!ops || !src || !dst || start >= end) return -EINVAL; memset(src, 0, sizeof(*src) * ((end - start) >> PAGE_SHIFT)); migrate.src = src; migrate.dst = dst; migrate.start = start; migrate.npages = 0; migrate.cpages = 0; migrate.end = end; migrate.vma = vma; /* Collect, and try to unmap source pages */ migrate_vma_collect(&migrate); if (!migrate.cpages) return 0; /* Lock and isolate page */ migrate_vma_prepare(&migrate); if (!migrate.cpages) return 0; /* Unmap pages */ migrate_vma_unmap(&migrate); if (!migrate.cpages) return 0; /* * At this point pages are locked and unmapped, and thus they have * stable content and can safely be copied to destination memory that * is allocated by the callback. * * Note that migration can fail in migrate_vma_struct_page() for each * individual page. */ ops->alloc_and_copy(vma, src, dst, start, end, private); /* This does the real migration of struct page */ migrate_vma_pages(&migrate); ops->finalize_and_map(vma, src, dst, start, end, private); /* Unlock and remap pages */ migrate_vma_finalize(&migrate); return 0; } EXPORT_SYMBOL(migrate_vma); #endif /* defined(MIGRATE_VMA_HELPER) */
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