| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Kairui Song | 828 | 93.88% | 9 | 40.91% |
| Mel Gorman | 27 | 3.06% | 3 | 13.64% |
| Neil Brown | 7 | 0.79% | 1 | 4.55% |
| Huang Ying | 5 | 0.57% | 1 | 4.55% |
| Shaohua Li | 4 | 0.45% | 1 | 4.55% |
| Linus Torvalds (pre-git) | 2 | 0.23% | 1 | 4.55% |
| Peter Zijlstra | 2 | 0.23% | 1 | 4.55% |
| Christoph Lameter | 2 | 0.23% | 1 | 4.55% |
| Davidlohr Bueso A | 2 | 0.23% | 1 | 4.55% |
| Greg Kroah-Hartman | 1 | 0.11% | 1 | 4.55% |
| David Hildenbrand | 1 | 0.11% | 1 | 4.55% |
| Matthew Wilcox | 1 | 0.11% | 1 | 4.55% |
| Total | 882 | 22 |
/* 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]; }; #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 |---- SHADOW_VAL ---|1| - Swapped out slot * PFN: | SWAP_COUNT |------ PFN -------|10| - Cached slot * Pointer: |----------- Pointer ----------|100| - (Unused) * Bad: |------------- 1 -------------|1000| - Bad slot * * SWAP_COUNT is `SWP_TB_COUNT_BITS` long, 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. */ #if defined(MAX_POSSIBLE_PHYSMEM_BITS) #define SWAP_CACHE_PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) #elif defined(MAX_PHYSMEM_BITS) #define SWAP_CACHE_PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT) #else #define SWAP_CACHE_PFN_BITS (BITS_PER_LONG - PAGE_SHIFT) #endif /* 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 + SWP_TB_PFN_MARK_BITS) #define SWP_TB_PFN_MARK 0b10UL #define SWP_TB_PFN_MARK_BITS 2 #define SWP_TB_PFN_MARK_MASK (BIT(SWP_TB_PFN_MARK_BITS) - 1) /* SWAP_COUNT part for PFN or shadow, the width can be shrunk or extended */ #define SWP_TB_COUNT_BITS min(4, BITS_PER_LONG - SWP_TB_PFN_BITS) #define SWP_TB_COUNT_MASK (~((~0UL) >> SWP_TB_COUNT_BITS)) #define SWP_TB_COUNT_SHIFT (BITS_PER_LONG - SWP_TB_COUNT_BITS) #define SWP_TB_COUNT_MAX ((1 << SWP_TB_COUNT_BITS) - 1) /* 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_COUNT_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_MAX < 2 || SWP_TB_COUNT_BITS < 2); VM_WARN_ON(count > SWP_TB_COUNT_MAX); return ((unsigned long)count) << SWP_TB_COUNT_SHIFT; } static inline unsigned long pfn_to_swp_tb(unsigned long pfn, unsigned int count) { unsigned long swp_tb; BUILD_BUG_ON(sizeof(unsigned long) != sizeof(void *)); BUILD_BUG_ON(SWAP_CACHE_PFN_BITS > (BITS_PER_LONG - SWP_TB_PFN_MARK_BITS - SWP_TB_COUNT_BITS)); swp_tb = (pfn << SWP_TB_PFN_MARK_BITS) | SWP_TB_PFN_MARK; VM_WARN_ON_ONCE(swp_tb & SWP_TB_COUNT_MASK); return swp_tb | __count_to_swp_tb(count); } static inline unsigned long folio_to_swp_tb(struct folio *folio, unsigned int count) { return pfn_to_swp_tb(folio_pfn(folio), count); } static inline unsigned long shadow_to_swp_tb(void *shadow, unsigned int count) { 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_COUNT_MASK)); return (unsigned long)shadow | __count_to_swp_tb(count) | SWP_TB_SHADOW_MARK; } /* * 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_COUNT_MASK) >> SWP_TB_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_COUNT_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 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; } #endif