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| author | Michal Hocko <mhocko@suse.com> | 2017-05-12 15:46:26 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-05-12 15:57:15 -0700 |
| commit | 18365225f0440d09708ad9daade2ec11275c3df9 (patch) | |
| tree | 9bf682111ea80465beb46c7bbc2f4ae7bc43f9e2 /mm | |
| parent | deac8429d62ca19c1571853e2a18f60e760ee04c (diff) | |
| download | linux-18365225f0440d09708ad9daade2ec11275c3df9.tar.gz linux-18365225f0440d09708ad9daade2ec11275c3df9.tar.bz2 linux-18365225f0440d09708ad9daade2ec11275c3df9.zip | |
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')
| -rw-r--r-- | mm/memcontrol.c | 2 | ||||
| -rw-r--r-- | mm/memory-failure.c | 7 |
2 files changed, 8 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ff73899af61a..94172089f52f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5528,7 +5528,7 @@ static void uncharge_list(struct list_head *page_list) next = page->lru.next; VM_BUG_ON_PAGE(PageLRU(page), page); - VM_BUG_ON_PAGE(page_count(page), page); + VM_BUG_ON_PAGE(!PageHWPoison(page) && page_count(page), page); if (!page->mem_cgroup) continue; 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) */ ClearPageActive(p); ClearPageUnevictable(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() */ |