Messages in this thread Patch in this message | | | Date | Wed, 18 Apr 2012 23:34:46 -0700 (PDT) | From | Hugh Dickins <> | Subject | [PATCH] memcg: fix Bad page state after replace_page_cache |
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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] ---
mm/memcontrol.c | 1 + 1 file changed, 1 insertion(+)
--- 3.4-rc3/mm/memcontrol.c 2012-04-15 20:47:37.151777506 -0700 +++ linux/mm/memcontrol.c 2012-04-18 22:29:18.490639511 -0700 @@ -3392,6 +3392,7 @@ void mem_cgroup_replace_page_cache(struc * 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); }
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