__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 in checking the flag in
memcg_kmem_newpage_charge or memcg_kmem_recharge_slab, because there's
no way how these two functions could result in recursion, if called from
memcg_kmem_get_cache. So let's remove the redundant code.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
mm/memcontrol.c | 31 -------------------------------
1 file changed, 31 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 52d1e933bb9f..d7de40cb3c8e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2717,34 +2717,6 @@ __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)) {
@@ -2800,9 +2772,6 @@ int __memcg_kmem_recharge_slab(void *obj, gfp_t gfp)
int nr_pages;
int ret = 0;
- if (current->memcg_kmem_skip_account)
- goto out;
-
page = virt_to_head_page(obj);
page_memcg = ACCESS_ONCE(page->mem_cgroup);
--
1.7.10.4
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