From 9b7f43afd417a6feb80841d30ced4051c362eb5d Mon Sep 17 00:00:00 2001 From: Hugh Dickins <hughd@google.com> Date: Wed, 18 Apr 2012 23:34:46 -0700 Subject: [PATCH] memcg: fix Bad page state after replace_page_cache My 9ce70c0240d0 "memcg: fix deadlock by inverting lrucare nesting" put a nasty little bug into v3.3's version of mem_cgroup_replace_page_cache(), sometimes used for FUSE. Replacing __mem_cgroup_commit_charge_lrucare() by __mem_cgroup_commit_charge(), I used the "pc" pointer set up earlier: but it's for oldpage, and needs now to be for newpage. Once oldpage was freed, its PageCgroupUsed bit (cleared above but set again here) caused "Bad page state" messages - and perhaps worse, being missed from newpage. (I didn't find this by using FUSE, but in reusing the function for tmpfs.) Signed-off-by: Hugh Dickins <hughd@google.com> Cc: stable@vger.kernel.org [v3.3 only] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- mm/memcontrol.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a7165a60d0a7d4..b868def9bcc1e1 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3392,6 +3392,7 @@ void mem_cgroup_replace_page_cache(struct page *oldpage, * the newpage may be on LRU(or pagevec for LRU) already. We lock * LRU while we overwrite pc->mem_cgroup. */ + pc = lookup_page_cgroup(newpage); __mem_cgroup_commit_charge(memcg, newpage, 1, pc, type, true); } -- GitLab