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| author | Roman Gushchin <guro@fb.com> | 2019-11-05 21:17:03 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-12 19:26:58 +0100 |
| commit | 8d16e0502ade195f0aa1e9f9c51c76e4a70b0d3a (patch) | |
| tree | bbfb3698b565ca610aa4703251404e6f53f09d64 /mm | |
| parent | 76e81b48fec824c40512194fa38551edf6d8c3de (diff) | |
| download | linux-stable-8d16e0502ade195f0aa1e9f9c51c76e4a70b0d3a.tar.gz linux-stable-8d16e0502ade195f0aa1e9f9c51c76e4a70b0d3a.tar.bz2 linux-stable-8d16e0502ade195f0aa1e9f9c51c76e4a70b0d3a.zip | |
mm: slab: make page_cgroup_ino() to recognize non-compound slab pages properly
commit 221ec5c0a46c1a1740f34fb36fc661a5284d01b0 upstream.
page_cgroup_ino() doesn't return a valid memcg pointer for non-compound
slab pages, because it depends on PgHead AND PgSlab flags to be set to
determine the memory cgroup from the kmem_cache. It's correct for
compound pages, but not for generic small pages. Those don't have PgHead
set, so it ends up returning zero.
Fix this by replacing the condition to PageSlab() && !PageTail().
Before this patch:
[root@localhost ~]# ./page-types -c /sys/fs/cgroup/user.slice/user-0.slice/user@0.service/ | grep slab
0x0000000000000080 38 0 _______S___________________________________ slab
After this patch:
[root@localhost ~]# ./page-types -c /sys/fs/cgroup/user.slice/user-0.slice/user@0.service/ | grep slab
0x0000000000000080 147 0 _______S___________________________________ slab
Also, hwpoison_filter_task() uses output of page_cgroup_ino() in order
to filter error injection events based on memcg. So if
page_cgroup_ino() fails to return memcg pointer, we just fail to inject
memory error. Considering that hwpoison filter is for testing, affected
users are limited and the impact should be marginal.
[n-horiguchi@ah.jp.nec.com: changelog additions]
Link: http://lkml.kernel.org/r/20191031012151.2722280-1-guro@fb.com
Fixes: 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
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.c | 2 | ||||
| -rw-r--r-- | mm/slab.h | 4 |
2 files changed, 3 insertions, 3 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index fc447c352611..89fd0829ebd0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -486,7 +486,7 @@ ino_t page_cgroup_ino(struct page *page) unsigned long ino = 0; rcu_read_lock(); - if (PageHead(page) && PageSlab(page)) + if (PageSlab(page) && !PageTail(page)) memcg = memcg_from_slab_page(page); else memcg = READ_ONCE(page->mem_cgroup); diff --git a/mm/slab.h b/mm/slab.h index 9057b8056b07..8d830e722398 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -259,8 +259,8 @@ static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s) * Expects a pointer to a slab page. Please note, that PageSlab() check * isn't sufficient, as it returns true also for tail compound slab pages, * which do not have slab_cache pointer set. - * So this function assumes that the page can pass PageHead() and PageSlab() - * checks. + * So this function assumes that the page can pass PageSlab() && !PageTail() + * check. * * The kmem_cache can be reparented asynchronously. The caller must ensure * the memcg lifetime, e.g. by taking rcu_read_lock() or cgroup_mutex. |