Contributors: 20
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Kairui Song |
1357 |
94.17% |
12 |
36.36% |
| Mel Gorman |
31 |
2.15% |
3 |
9.09% |
| Neil Brown |
7 |
0.49% |
1 |
3.03% |
| Randy Dunlap |
6 |
0.42% |
1 |
3.03% |
| Huang Ying |
5 |
0.35% |
1 |
3.03% |
| Nicholas Piggin |
4 |
0.28% |
1 |
3.03% |
| Song Muchun |
4 |
0.28% |
1 |
3.03% |
| Shaohua Li |
4 |
0.28% |
1 |
3.03% |
| Yang Yang |
4 |
0.28% |
1 |
3.03% |
| Ezequiel García |
3 |
0.21% |
1 |
3.03% |
| Davidlohr Bueso A |
2 |
0.14% |
1 |
3.03% |
| Roman Gushchin |
2 |
0.14% |
1 |
3.03% |
| Peter Zijlstra |
2 |
0.14% |
1 |
3.03% |
| Linus Torvalds (pre-git) |
2 |
0.14% |
1 |
3.03% |
| Kamezawa Hiroyuki |
2 |
0.14% |
1 |
3.03% |
| Christoph Lameter |
2 |
0.14% |
1 |
3.03% |
| David Hildenbrand |
1 |
0.07% |
1 |
3.03% |
| Greg Kroah-Hartman |
1 |
0.07% |
1 |
3.03% |
| Matthew Wilcox |
1 |
0.07% |
1 |
3.03% |
| Andrew Morton |
1 |
0.07% |
1 |
3.03% |
| Total |
1441 |
|
33 |
|
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _MM_SWAP_TABLE_H
#define _MM_SWAP_TABLE_H
#include <linux/rcupdate.h>
#include <linux/atomic.h>
#include "swap.h"
/* A typical flat array in each cluster as swap table */
struct swap_table {
atomic_long_t entries[SWAPFILE_CLUSTER];
};
/* For storing memcg private id */
struct swap_memcg_table {
unsigned short id[SWAPFILE_CLUSTER];
};
#define SWP_TABLE_USE_PAGE (sizeof(struct swap_table) == PAGE_SIZE)
/*
* A swap table entry represents the status of a swap slot on a swap
* (physical or virtual) device. The swap table in each cluster is a
* 1:1 map of the swap slots in this cluster.
*
* Swap table entry type and bits layouts:
*
* NULL: |---------------- 0 ---------------| - Free slot
* Shadow: |SWAP_COUNT|Z|---- SHADOW_VAL ---|1| - Swapped out slot
* PFN: |SWAP_COUNT|Z|------ PFN -------|10| - Cached slot
* Pointer: |----------- Pointer ----------|100| - (Unused)
* Bad: |------------- 1 -------------|1000| - Bad slot
*
* COUNT is `SWP_TB_COUNT_BITS` long, Z is the `SWP_TB_ZERO_FLAG` bit,
* and together they form the `SWP_TB_FLAGS_BITS` wide flags field.
* Each entry is an atomic long.
*
* Usages:
*
* - NULL: Swap slot is unused, could be allocated.
*
* - Shadow: Swap slot is used and not cached (usually swapped out). It reuses
* the XA_VALUE format to be compatible with working set shadows. SHADOW_VAL
* part might be all 0 if the working shadow info is absent. In such a case,
* we still want to keep the shadow format as a placeholder.
*
* Memcg ID is embedded in SHADOW_VAL.
*
* - PFN: Swap slot is in use, and cached. Memcg info is recorded on the page
* struct.
*
* - Pointer: Unused yet. `0b100` is reserved for potential pointer usage
* because only the lower three bits can be used as a marker for 8 bytes
* aligned pointers.
*
* - Bad: Swap slot is reserved, protects swap header or holes on swap devices.
*/
/* NULL Entry, all 0 */
#define SWP_TB_NULL 0UL
/* Swapped out: shadow */
#define SWP_TB_SHADOW_MARK 0b1UL
/* Cached: PFN */
#define SWP_TB_PFN_BITS (SWAP_CACHE_PFN_BITS + SWAP_CACHE_PFN_MARK_BITS)
#define SWP_TB_PFN_MARK 0b10UL
#define SWP_TB_PFN_MARK_MASK (BIT(SWAP_CACHE_PFN_MARK_BITS) - 1)
/* Flags: For PFN or shadow, contains SWAP_COUNT, width changes */
#define SWP_TB_FLAGS_BITS min(5, BITS_PER_LONG - SWP_TB_PFN_BITS)
#define SWP_TB_COUNT_BITS (SWP_TB_FLAGS_BITS - SWAP_TABLE_HAS_ZEROFLAG)
#define SWP_TB_FLAGS_MASK (~((~0UL) >> SWP_TB_FLAGS_BITS))
#define SWP_TB_COUNT_MASK (~((~0UL) >> SWP_TB_COUNT_BITS))
#define SWP_TB_FLAGS_SHIFT (BITS_PER_LONG - SWP_TB_FLAGS_BITS)
#define SWP_TB_COUNT_SHIFT (BITS_PER_LONG - SWP_TB_COUNT_BITS)
#define SWP_TB_COUNT_MAX ((1 << SWP_TB_COUNT_BITS) - 1)
/* The first flag is zero bit (SWAP_TABLE_HAS_ZEROFLAG) */
#define SWP_TB_ZERO_FLAG BIT(BITS_PER_LONG - SWP_TB_FLAGS_BITS)
/* Bad slot: ends with 0b1000 and rests of bits are all 1 */
#define SWP_TB_BAD ((~0UL) << 3)
/* Macro for shadow offset calculation */
#define SWAP_COUNT_SHIFT SWP_TB_FLAGS_BITS
/*
* Helpers for casting one type of info into a swap table entry.
*/
static inline unsigned long null_to_swp_tb(void)
{
BUILD_BUG_ON(sizeof(unsigned long) != sizeof(atomic_long_t));
return 0;
}
static inline unsigned long __count_to_swp_tb(unsigned char count)
{
/*
* At least three values are needed to distinguish free (0),
* used (count > 0 && count < SWP_TB_COUNT_MAX), and
* overflow (count == SWP_TB_COUNT_MAX).
*/
BUILD_BUG_ON(SWP_TB_COUNT_BITS < SWAP_COUNT_MIN_BITS);
VM_WARN_ON(count > SWP_TB_COUNT_MAX);
return ((unsigned long)count) << SWP_TB_COUNT_SHIFT;
}
static inline unsigned long __flags_to_swp_tb(unsigned char flags)
{
BUILD_BUG_ON(SWP_TB_FLAGS_BITS > BITS_PER_BYTE);
VM_WARN_ON(flags >> SWP_TB_FLAGS_BITS);
return ((unsigned long)flags) << SWP_TB_FLAGS_SHIFT;
}
static inline unsigned long pfn_to_swp_tb(unsigned long pfn, unsigned char flags)
{
unsigned long swp_tb;
BUILD_BUG_ON(sizeof(unsigned long) != sizeof(void *));
BUILD_BUG_ON(SWAP_CACHE_PFN_BITS >
(BITS_PER_LONG - SWAP_CACHE_PFN_MARK_BITS - SWP_TB_FLAGS_BITS));
swp_tb = (pfn << SWAP_CACHE_PFN_MARK_BITS) | SWP_TB_PFN_MARK;
VM_WARN_ON_ONCE(swp_tb & SWP_TB_FLAGS_MASK);
return swp_tb | __flags_to_swp_tb(flags);
}
static inline unsigned long folio_to_swp_tb(struct folio *folio, unsigned char flags)
{
return pfn_to_swp_tb(folio_pfn(folio), flags);
}
static inline unsigned long shadow_to_swp_tb(void *shadow, unsigned char flags)
{
BUILD_BUG_ON((BITS_PER_XA_VALUE + 1) !=
BITS_PER_BYTE * sizeof(unsigned long));
BUILD_BUG_ON((unsigned long)xa_mk_value(0) != SWP_TB_SHADOW_MARK);
VM_WARN_ON_ONCE(shadow && !xa_is_value(shadow));
VM_WARN_ON_ONCE(shadow && ((unsigned long)shadow & SWP_TB_FLAGS_MASK));
return (unsigned long)shadow | SWP_TB_SHADOW_MARK | __flags_to_swp_tb(flags);
}
/*
* Helpers for swap table entry type checking.
*/
static inline bool swp_tb_is_null(unsigned long swp_tb)
{
return !swp_tb;
}
static inline bool swp_tb_is_folio(unsigned long swp_tb)
{
return ((swp_tb & SWP_TB_PFN_MARK_MASK) == SWP_TB_PFN_MARK);
}
static inline bool swp_tb_is_shadow(unsigned long swp_tb)
{
return xa_is_value((void *)swp_tb);
}
static inline bool swp_tb_is_bad(unsigned long swp_tb)
{
return swp_tb == SWP_TB_BAD;
}
static inline bool swp_tb_is_countable(unsigned long swp_tb)
{
return (swp_tb_is_shadow(swp_tb) || swp_tb_is_folio(swp_tb) ||
swp_tb_is_null(swp_tb));
}
/*
* Helpers for retrieving info from swap table.
*/
static inline struct folio *swp_tb_to_folio(unsigned long swp_tb)
{
VM_WARN_ON(!swp_tb_is_folio(swp_tb));
return pfn_folio((swp_tb & ~SWP_TB_FLAGS_MASK) >> SWAP_CACHE_PFN_MARK_BITS);
}
static inline void *swp_tb_to_shadow(unsigned long swp_tb)
{
VM_WARN_ON(!swp_tb_is_shadow(swp_tb));
/* No shift needed, xa_value is stored as it is in the lower bits. */
return (void *)(swp_tb & ~SWP_TB_FLAGS_MASK);
}
static inline unsigned char __swp_tb_get_count(unsigned long swp_tb)
{
VM_WARN_ON(!swp_tb_is_countable(swp_tb));
return ((swp_tb & SWP_TB_COUNT_MASK) >> SWP_TB_COUNT_SHIFT);
}
static inline unsigned char __swp_tb_get_flags(unsigned long swp_tb)
{
VM_WARN_ON(!swp_tb_is_countable(swp_tb));
return ((swp_tb & SWP_TB_FLAGS_MASK) >> SWP_TB_FLAGS_SHIFT);
}
static inline int swp_tb_get_count(unsigned long swp_tb)
{
if (swp_tb_is_countable(swp_tb))
return __swp_tb_get_count(swp_tb);
return -EINVAL;
}
static inline unsigned long __swp_tb_mk_count(unsigned long swp_tb, int count)
{
return ((swp_tb & ~SWP_TB_COUNT_MASK) | __count_to_swp_tb(count));
}
/*
* Helpers for accessing or modifying the swap table of a cluster,
* the swap cluster must be locked.
*/
static inline void __swap_table_set(struct swap_cluster_info *ci,
unsigned int off, unsigned long swp_tb)
{
atomic_long_t *table = rcu_dereference_protected(ci->table, true);
lockdep_assert_held(&ci->lock);
VM_WARN_ON_ONCE(off >= SWAPFILE_CLUSTER);
atomic_long_set(&table[off], swp_tb);
}
static inline unsigned long __swap_table_xchg(struct swap_cluster_info *ci,
unsigned int off, unsigned long swp_tb)
{
atomic_long_t *table = rcu_dereference_protected(ci->table, true);
lockdep_assert_held(&ci->lock);
VM_WARN_ON_ONCE(off >= SWAPFILE_CLUSTER);
/* Ordering is guaranteed by cluster lock, relax */
return atomic_long_xchg_relaxed(&table[off], swp_tb);
}
static inline unsigned long __swap_table_get(struct swap_cluster_info *ci,
unsigned int off)
{
atomic_long_t *table;
VM_WARN_ON_ONCE(off >= SWAPFILE_CLUSTER);
table = rcu_dereference_check(ci->table, lockdep_is_held(&ci->lock));
return atomic_long_read(&table[off]);
}
static inline unsigned long swap_table_get(struct swap_cluster_info *ci,
unsigned int off)
{
atomic_long_t *table;
unsigned long swp_tb;
VM_WARN_ON_ONCE(off >= SWAPFILE_CLUSTER);
rcu_read_lock();
table = rcu_dereference(ci->table);
swp_tb = table ? atomic_long_read(&table[off]) : null_to_swp_tb();
rcu_read_unlock();
return swp_tb;
}
static inline void __swap_table_set_zero(struct swap_cluster_info *ci,
unsigned int ci_off)
{
#if SWAP_TABLE_HAS_ZEROFLAG
unsigned long swp_tb = __swap_table_get(ci, ci_off);
BUILD_BUG_ON(SWP_TB_ZERO_FLAG & ~SWP_TB_FLAGS_MASK);
VM_WARN_ON(!swp_tb_is_countable(swp_tb));
swp_tb |= SWP_TB_ZERO_FLAG;
__swap_table_set(ci, ci_off, swp_tb);
#else
lockdep_assert_held(&ci->lock);
__set_bit(ci_off, ci->zero_bitmap);
#endif
}
static inline bool __swap_table_test_zero(struct swap_cluster_info *ci,
unsigned int ci_off)
{
#if SWAP_TABLE_HAS_ZEROFLAG
unsigned long swp_tb = __swap_table_get(ci, ci_off);
VM_WARN_ON(!swp_tb_is_countable(swp_tb));
return !!(swp_tb & SWP_TB_ZERO_FLAG);
#else
return test_bit(ci_off, ci->zero_bitmap);
#endif
}
static inline void __swap_table_clear_zero(struct swap_cluster_info *ci,
unsigned int ci_off)
{
#if SWAP_TABLE_HAS_ZEROFLAG
unsigned long swp_tb = __swap_table_get(ci, ci_off);
VM_WARN_ON(!swp_tb_is_countable(swp_tb));
swp_tb &= ~SWP_TB_ZERO_FLAG;
__swap_table_set(ci, ci_off, swp_tb);
#else
lockdep_assert_held(&ci->lock);
__clear_bit(ci_off, ci->zero_bitmap);
#endif
}
#ifdef CONFIG_MEMCG
static inline void __swap_cgroup_set(struct swap_cluster_info *ci,
unsigned int ci_off, unsigned long nr, unsigned short id)
{
lockdep_assert_held(&ci->lock);
VM_WARN_ON_ONCE(ci_off >= SWAPFILE_CLUSTER);
if (WARN_ON_ONCE(!ci->memcg_table))
return;
do {
ci->memcg_table->id[ci_off++] = id;
} while (--nr);
}
static inline unsigned short __swap_cgroup_get(struct swap_cluster_info *ci,
unsigned int ci_off)
{
lockdep_assert_held(&ci->lock);
VM_WARN_ON_ONCE(ci_off >= SWAPFILE_CLUSTER);
if (unlikely(!ci->memcg_table))
return 0;
return ci->memcg_table->id[ci_off];
}
static inline unsigned short __swap_cgroup_clear(struct swap_cluster_info *ci,
unsigned int ci_off,
unsigned long nr)
{
unsigned short old = __swap_cgroup_get(ci, ci_off);
if (!old)
return 0;
do {
VM_WARN_ON_ONCE(ci->memcg_table->id[ci_off] != old);
ci->memcg_table->id[ci_off++] = 0;
} while (--nr);
return old;
}
#else
static inline void __swap_cgroup_set(struct swap_cluster_info *ci,
unsigned int ci_off, unsigned long nr, unsigned short id)
{
}
static inline unsigned short __swap_cgroup_get(struct swap_cluster_info *ci,
unsigned int ci_off)
{
return 0;
}
static inline unsigned short __swap_cgroup_clear(struct swap_cluster_info *ci,
unsigned int ci_off,
unsigned long nr)
{
return 0;
}
#endif
#endif