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authorMichal Hocko <mhocko@suse.com>2017-05-12 15:46:26 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-01-31 12:55:51 +0100
commitbc0e2174b092638f1146d792a8be71ab90a7e56d (patch)
treeb67fd845a669688af419f4f651b1cf81e61d22cf /mm
parentc57664bd12997742da5e12556e328e1ec0b5b654 (diff)
hwpoison, memcg: forcibly uncharge LRU pages
commit 18365225f0440d09708ad9daade2ec11275c3df9 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c2
-rw-r--r--mm/memory-failure.c7
2 files changed, 8 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2a800c4a39bd..50088150fc17 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5531,7 +5531,7 @@ 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 ce7d416edab7..5aa71a82ca73 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -535,6 +535,13 @@ 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()
*/