diff options
author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2009-06-16 15:32:53 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-16 19:47:42 -0700 |
commit | 355cfa73ddff2fb8fa14e93bd94a057cc022512e (patch) | |
tree | 7ff70cd56d533070d50b06db6ba0086e8aab0d71 /include | |
parent | cb4b86ba47bb0937b71fb825b3ed88adf7a190f0 (diff) | |
download | linux-355cfa73ddff2fb8fa14e93bd94a057cc022512e.tar.gz |
mm: modify swap_map and add SWAP_HAS_CACHE flag
This is a part of the patches for fixing memcg's swap accountinf leak. But, IMHO, not a bad patch even if no memcg. There are 2 kinds of references to swap. - reference from swap entry - reference from swap cache Then, - If there is swap cache && swap's refcnt is 1, there is only swap cache. (*) swapcount(entry) == 1 && find_get_page(swapper_space, entry) != NULL This counting logic have worked well for a long time. But considering that we cannot know there is a _real_ reference or not by swap_map[], current usage of counter is not very good. This patch adds a flag SWAP_HAS_CACHE and recored information that a swap entry has a cache or not. This will remove -1 magic used in swapfile.c and be a help to avoid unnecessary find_get_page(). Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/swap.h | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index 259e96c150ef..fed5e8e1104b 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -129,9 +129,10 @@ enum { #define SWAP_CLUSTER_MAX 32 -#define SWAP_MAP_MAX 0x7fff -#define SWAP_MAP_BAD 0x8000 - +#define SWAP_MAP_MAX 0x7ffe +#define SWAP_MAP_BAD 0x7fff +#define SWAP_HAS_CACHE 0x8000 /* There is a swap cache of entry. */ +#define SWAP_COUNT_MASK (~SWAP_HAS_CACHE) /* * The in-memory structure used to track swap areas. */ @@ -281,7 +282,7 @@ extern long total_swap_pages; extern void si_swapinfo(struct sysinfo *); extern swp_entry_t get_swap_page(void); extern swp_entry_t get_swap_page_of_type(int); -extern int swap_duplicate(swp_entry_t); +extern void swap_duplicate(swp_entry_t); extern int swapcache_prepare(swp_entry_t); extern int valid_swaphandles(swp_entry_t, unsigned long *); extern void swap_free(swp_entry_t); @@ -353,9 +354,12 @@ static inline void show_swap_cache_info(void) } #define free_swap_and_cache(swp) is_migration_entry(swp) -#define swap_duplicate(swp) is_migration_entry(swp) #define swapcache_prepare(swp) is_migration_entry(swp) +static inline void swap_duplicate(swp_entry_t swp) +{ +} + static inline void swap_free(swp_entry_t swp) { } |