memcg: turn memcg_kmem_skip_account into a bit field
It isn't supposed to stack, so turn it into a bit-field to save 4 bytes on
the task_struct.
Also, remove the memcg_stop/resume_kmem_account helpers - it is clearer to
set/clear the flag inline. Regarding the overwhelming comment to the
helpers, which is removed by this patch too, we already have a compact yet
accurate explanation in memcg_schedule_cache_create, no need in yet
another one.
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>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d9fab72..11cbfde 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2673,37 +2673,6 @@
css_put(&memcg->css);
}
-/*
- * During the creation a new cache, we need to disable our accounting mechanism
- * altogether. This is true even if we are not creating, but rather just
- * enqueing new caches to be created.
- *
- * This is because that process will trigger allocations; some visible, like
- * explicit kmallocs to auxiliary data structures, name strings and internal
- * cache structures; some well concealed, like INIT_WORK() that can allocate
- * objects during debug.
- *
- * If any allocation happens during memcg_kmem_get_cache, we will recurse back
- * to it. This may not be a bounded recursion: since the first cache creation
- * failed to complete (waiting on the allocation), we'll just try to create the
- * cache again, failing at the same point.
- *
- * memcg_kmem_get_cache is prepared to abort after seeing a positive count of
- * memcg_kmem_skip_account. So we enclose anything that might allocate memory
- * inside the following two functions.
- */
-static inline void memcg_stop_kmem_account(void)
-{
- VM_BUG_ON(!current->mm);
- current->memcg_kmem_skip_account++;
-}
-
-static inline void memcg_resume_kmem_account(void)
-{
- VM_BUG_ON(!current->mm);
- current->memcg_kmem_skip_account--;
-}
-
int __memcg_cleanup_cache_params(struct kmem_cache *s)
{
struct kmem_cache *c;
@@ -2798,9 +2767,9 @@
* this point we can't allow ourselves back into memcg_kmem_get_cache,
* the safest choice is to do it like this, wrapping the whole function.
*/
- memcg_stop_kmem_account();
+ current->memcg_kmem_skip_account = 1;
__memcg_schedule_register_cache(memcg, cachep);
- memcg_resume_kmem_account();
+ current->memcg_kmem_skip_account = 0;
}
int __memcg_charge_slab(struct kmem_cache *cachep, gfp_t gfp, int order)