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authorVladimir Davydov <vdavydov@parallels.com>2014-12-13 03:55:13 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-13 23:42:47 +0300
commit4e701d7b37789d1aeb0015210b373912e5d30733 (patch)
tree38257203476057e32f32de241f0d6dc2b7e11891 /mm
parent900a38f027b37b55ebe157a0cb31de351b91e4e2 (diff)
downloadlinux-4e701d7b37789d1aeb0015210b373912e5d30733.tar.xz
memcg: only check memcg_kmem_skip_account in __memcg_kmem_get_cache
__memcg_kmem_get_cache can recurse if it calls kmalloc (which it does if the cgroup's kmem cache doesn't exist), because kmalloc may call __memcg_kmem_get_cache internally again. To avoid the recursion, we use the task_struct->memcg_kmem_skip_account flag. However, there's no need checking the flag in memcg_kmem_newpage_charge, because there's no way how this function could result in recursion, if called from memcg_kmem_get_cache. So let's remove the redundant code. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c28
1 files changed, 0 insertions, 28 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bb8c237026cc..d9fab72da52e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2905,34 +2905,6 @@ __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order)
*_memcg = NULL;
- /*
- * Disabling accounting is only relevant for some specific memcg
- * internal allocations. Therefore we would initially not have such
- * check here, since direct calls to the page allocator that are
- * accounted to kmemcg (alloc_kmem_pages and friends) only happen
- * outside memcg core. We are mostly concerned with cache allocations,
- * and by having this test at memcg_kmem_get_cache, we are already able
- * to relay the allocation to the root cache and bypass the memcg cache
- * altogether.
- *
- * There is one exception, though: the SLUB allocator does not create
- * large order caches, but rather service large kmallocs directly from
- * the page allocator. Therefore, the following sequence when backed by
- * the SLUB allocator:
- *
- * memcg_stop_kmem_account();
- * kmalloc(<large_number>)
- * memcg_resume_kmem_account();
- *
- * would effectively ignore the fact that we should skip accounting,
- * since it will drive us directly to this function without passing
- * through the cache selector memcg_kmem_get_cache. Such large
- * allocations are extremely rare but can happen, for instance, for the
- * cache arrays. We bring this test here.
- */
- if (current->memcg_kmem_skip_account)
- return true;
-
memcg = get_mem_cgroup_from_mm(current->mm);
if (!memcg_kmem_is_active(memcg)) {