diff options
| author | Glauber Costa <glommer@parallels.com> | 2012-12-19 02:23:10 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-19 03:02:15 +0400 |
| commit | ebe945c27628fca03723582eba138acc2e2f3d15 (patch) | |
| tree | 5998e8dd874aedf3b8873d0ffeaf658d10505655 /include | |
| parent | 92e793495597af4135d94314113bf13eafb0e663 (diff) | |
| download | linux-ebe945c27628fca03723582eba138acc2e2f3d15.tar.xz | |
memcg: add comments clarifying aspects of cache attribute propagation
This patch clarifies two aspects of cache attribute propagation.
First, the expected context for the for_each_memcg_cache macro in
memcontrol.h. The usages already in the codebase are safe. In mm/slub.c,
it is trivially safe because the lock is acquired right before the loop.
In mm/slab.c, it is less so: the lock is acquired by an outer function a
few steps back in the stack, so a VM_BUG_ON() is added to make sure it is
indeed safe.
A comment is also added to detail why we are returning the value of the
parent cache and ignoring the children's when we propagate the attributes.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/memcontrol.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index ea02ff970836..0108a56f814e 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -422,6 +422,12 @@ static inline void sock_release_memcg(struct sock *sk) extern struct static_key memcg_kmem_enabled_key; extern int memcg_limited_groups_array_size; + +/* + * Helper macro to loop through all memcg-specific caches. Callers must still + * check if the cache is valid (it is either valid or NULL). + * the slab_mutex must be held when looping through those caches + */ #define for_each_memcg_cache_index(_idx) \ for ((_idx) = 0; i < memcg_limited_groups_array_size; (_idx)++) |