path: root/mm/memory-failure.c
diff options
authorMichal Hocko <mhocko@suse.com>2017-05-12 15:46:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-12 15:57:15 -0700
commit18365225f0440d09708ad9daade2ec11275c3df9 (patch)
tree9bf682111ea80465beb46c7bbc2f4ae7bc43f9e2 /mm/memory-failure.c
parentdeac8429d62ca19c1571853e2a18f60e760ee04c (diff)
hwpoison, memcg: forcibly uncharge LRU pages
Laurent Dufour has noticed that hwpoinsoned pages are kept charged. In his particular case he has hit a bad_page("page still charged to cgroup") when onlining a hwpoison page. While this looks like something that shouldn't happen in the first place because onlining hwpages and returning them to the page allocator makes only little sense it shows a real problem. hwpoison pages do not get freed usually so we do not uncharge them (at least not since commit 0a31bc97c80c ("mm: memcontrol: rewrite uncharge API")). Each charge pins memcg (since e8ea14cc6ead ("mm: memcontrol: take a css reference for each charged page")) as well and so the mem_cgroup and the associated state will never go away. Fix this leak by forcibly uncharging a LRU hwpoisoned page in delete_from_lru_cache(). We also have to tweak uncharge_list because it cannot rely on zero ref count for these pages. [akpm@linux-foundation.org: coding-style fixes] Fixes: 0a31bc97c80c ("mm: memcontrol: rewrite uncharge API") Link: http://lkml.kernel.org/r/20170502185507.GB19165@dhcp22.suse.cz Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> Tested-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> Reviewed-by: Balbir Singh <bsingharora@gmail.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory-failure.c')
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 73066b80d14a..2527dfeddb00 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -539,6 +539,13 @@ static int delete_from_lru_cache(struct page *p)
+ /*
+ * Poisoned page might never drop its ref count to 0 so we have
+ * to uncharge it manually from its memcg.
+ */
+ mem_cgroup_uncharge(p);
* drop the page count elevated by isolate_lru_page()

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