diff options
| author | Nhat Pham <nphamcs@gmail.com> | 2025-12-20 03:43:37 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-01-31 14:22:55 -0800 |
| commit | bc617c990eae4259cd5014d596477cbe0d596417 (patch) | |
| tree | d54e433a73165a10a90e77f157d2bae48334001b /include/linux/swap.h | |
| parent | c246d236b18befdfeb82ce2a01e23d45cb5eeea6 (diff) | |
mm/shmem, swap: remove SWAP_MAP_SHMEM
The SWAP_MAP_SHMEM state was introduced in the commit aaa468653b4a
("swap_info: note SWAP_MAP_SHMEM"), to quickly determine if a swap entry
belongs to shmem during swapoff.
However, swapoff has since been rewritten in the commit b56a2d8af914 ("mm:
rid swapoff of quadratic complexity"). Now having swap count ==
SWAP_MAP_SHMEM value is basically the same as having swap count == 1, and
swap_shmem_alloc() behaves analogously to swap_duplicate(). The only
difference of note is that swap_shmem_alloc() does not check for -ENOMEM
returned from __swap_duplicate(), but it is OK because shmem never
re-duplicates any swap entry it owns. This will stil be safe if we use
(batched) swap_duplicate() instead.
This commit adds swap_duplicate_nr(), the batched variant of
swap_duplicate(), and removes the SWAP_MAP_SHMEM state and the associated
swap_shmem_alloc() helper to simplify the state machine (both mentally and
in terms of actual code). We will also have an extra state/special value
that can be repurposed (for swap entries that never gets re-duplicated).
Link: https://lkml.kernel.org/r/20251220-swap-table-p2-v5-8-8862a265a033@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Deepanshu Kartikey <kartikey406@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/swap.h')
| -rw-r--r-- | include/linux/swap.h | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index 38ca3df68716..bf72b548a96d 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -230,7 +230,6 @@ enum { /* Special value in first swap_map */ #define SWAP_MAP_MAX 0x3e /* Max count */ #define SWAP_MAP_BAD 0x3f /* Note page is bad */ -#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs */ /* Special value in each swap_map continuation */ #define SWAP_CONT_MAX 0x7f /* Max count */ @@ -458,8 +457,7 @@ bool folio_free_swap(struct folio *folio); void put_swap_folio(struct folio *folio, swp_entry_t entry); extern swp_entry_t get_swap_page_of_type(int); extern int add_swap_count_continuation(swp_entry_t, gfp_t); -extern void swap_shmem_alloc(swp_entry_t, int); -extern int swap_duplicate(swp_entry_t); +extern int swap_duplicate_nr(swp_entry_t entry, int nr); extern int swapcache_prepare(swp_entry_t entry, int nr); extern void swap_free_nr(swp_entry_t entry, int nr_pages); extern void free_swap_and_cache_nr(swp_entry_t entry, int nr); @@ -514,11 +512,7 @@ static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask) return 0; } -static inline void swap_shmem_alloc(swp_entry_t swp, int nr) -{ -} - -static inline int swap_duplicate(swp_entry_t swp) +static inline int swap_duplicate_nr(swp_entry_t swp, int nr_pages) { return 0; } @@ -569,6 +563,11 @@ static inline int add_swap_extent(struct swap_info_struct *sis, } #endif /* CONFIG_SWAP */ +static inline int swap_duplicate(swp_entry_t entry) +{ + return swap_duplicate_nr(entry, 1); +} + static inline void free_swap_and_cache(swp_entry_t entry) { free_swap_and_cache_nr(entry, 1); |