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authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2009-05-28 14:34:28 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-05-29 08:40:02 -0700
commite767e0561d7fd2333df1921f1ab4176211f9036b (patch)
tree3b936733f80ceb1ee61ce99f927d002d2296250e /mm/vmscan.c
parentbd6daba909d8484bd2ccf6017db4028d7a420927 (diff)
downloadop-kernel-dev-e767e0561d7fd2333df1921f1ab4176211f9036b.zip
op-kernel-dev-e767e0561d7fd2333df1921f1ab4176211f9036b.tar.gz
memcg: fix deadlock between lock_page_cgroup and mapping tree_lock
mapping->tree_lock can be acquired from interrupt context. Then, following dead lock can occur. Assume "A" as a page. CPU0: lock_page_cgroup(A) interrupted -> take mapping->tree_lock. CPU1: take mapping->tree_lock -> lock_page_cgroup(A) This patch tries to fix above deadlock by moving memcg's hook to out of mapping->tree_lock. charge/uncharge of pagecache/swapcache is protected by page lock, not tree_lock. After this patch, lock_page_cgroup() is not called under mapping->tree_lock. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5fa3eda..d254306 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -470,10 +470,12 @@ static int __remove_mapping(struct address_space *mapping, struct page *page)
swp_entry_t swap = { .val = page_private(page) };
__delete_from_swap_cache(page);
spin_unlock_irq(&mapping->tree_lock);
+ mem_cgroup_uncharge_swapcache(page, swap);
swap_free(swap);
} else {
__remove_from_page_cache(page);
spin_unlock_irq(&mapping->tree_lock);
+ mem_cgroup_uncharge_cache_page(page);
}
return 1;
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