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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: 4d96ba3 ("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]>
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