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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 /kernel/rcuclassic.c | |
parent | cb4b86ba47bb0937b71fb825b3ed88adf7a190f0 (diff) | |
download | linux-355cfa73ddff2fb8fa14e93bd94a057cc022512e.tar.bz2 |
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 'kernel/rcuclassic.c')
0 files changed, 0 insertions, 0 deletions