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author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2010-04-06 14:35:05 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-04-07 08:38:05 -0700 |
commit | 8725d5416213a145ccc9c236dbd26830ba409e00 (patch) | |
tree | aff10fc98874adfcb7755ec8bc1f2627036e8dc2 /drivers/rtc | |
parent | 116354d177ba2da37e91cf884e3d11e67f825efd (diff) | |
download | kernel_samsung_aries-8725d5416213a145ccc9c236dbd26830ba409e00.zip kernel_samsung_aries-8725d5416213a145ccc9c236dbd26830ba409e00.tar.gz kernel_samsung_aries-8725d5416213a145ccc9c236dbd26830ba409e00.tar.bz2 |
memcg: fix race in file_mapped accounting
Presently, memcg's FILE_MAPPED accounting has following race with
move_account (happens at rmdir()).
increment page->mapcount (rmap.c)
mem_cgroup_update_file_mapped() move_account()
lock_page_cgroup()
check page_mapped() if
page_mapped(page)>1 {
FILE_MAPPED -1 from old memcg
FILE_MAPPED +1 to old memcg
}
.....
overwrite pc->mem_cgroup
unlock_page_cgroup()
lock_page_cgroup()
FILE_MAPPED + 1 to pc->mem_cgroup
unlock_page_cgroup()
Then,
old memcg (-1 file mapped)
new memcg (+2 file mapped)
This happens because move_account see page_mapped() which is not guarded
by lock_page_cgroup(). This patch adds FILE_MAPPED flag to page_cgroup
and move account information based on it. Now, all checks are synchronous
with lock_page_cgroup().
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Balbir Singh <balbir@in.ibm.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Andrea Righi <arighi@develer.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/rtc')
0 files changed, 0 insertions, 0 deletions