diff options
| author | Roman Gushchin <[email protected]> | 2019-11-05 21:17:03 -0800 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2019-11-06 08:47:50 -0800 |
| commit | 221ec5c0a46c1a1740f34fb36fc661a5284d01b0 (patch) | |
| tree | 8b8b525a456d2dec971ce88dab5a60dbe5f3b630 | |
| parent | 6981b76cf6f3252ed7b828fc9b2d333ff5f0bde8 (diff) | |
mm: slab: make page_cgroup_ino() to recognize non-compound slab pages properly
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/[email protected]/ | grep slab
0x0000000000000080 38 0 _______S___________________________________ slab
After this patch:
[root@localhost ~]# ./page-types -c /sys/fs/cgroup/user.slice/user-0.slice/[email protected]/ | 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.
[[email protected]: changelog additions]
Link: http://lkml.kernel.org/r/[email protected]
Fixes: 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
Signed-off-by: Roman Gushchin <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Acked-by: David Rientjes <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Daniel Jordan <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -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 0507b1cfd7e8..2655c07baada 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -484,7 +484,7 @@ 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 68e455f2b698..b2b01694dc43 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -323,8 +323,8 @@ 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. |