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Commit 24467cac authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
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mm: memcg: remove needless !mm fixup to init_mm when charging 



It does not matter to __mem_cgroup_try_charge() if the passed mm is NULL
or init_mm, it will charge the root memcg in either case.

Also fix up the comment in __mem_cgroup_try_charge() that claimed the
init_mm would be charged when no mm was passed.  It's not really
incorrect, but confusing.  Clarify that the root memcg is charged in this
case.

Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Wanpeng Li <liwp.linux@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 62ba7442

mm/memcontrol.c

+1 −6
Original line number Diff line number Diff line
@@ -2333,7 +2333,7 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, 
	 * We always charge the cgroup the mm_struct belongs to.

	 * The mm_struct's mem_cgroup changes on task migration if the

	 * thread group leader migrates. It's possible that mm is not

	 * set, if so charge the init_mm (happens for pagecache usage).

	 * set, if so charge the root memcg (happens for pagecache usage).

	 */

	if (!*ptr && !mm)

		*ptr = root_mem_cgroup;
@@ -2833,8 +2833,6 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm, 
		ret = 0;

	return ret;

charge_cur_mm:

	if (unlikely(!mm))

		mm = &init_mm;

	ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);

	if (ret == -EINTR)

		ret = 0;
@@ -2899,9 +2897,6 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, 
	if (PageCompound(page))

		return 0;



	if (unlikely(!mm))

		mm = &init_mm;



	if (!PageSwapCache(page))

		ret = mem_cgroup_charge_common(page, mm, gfp_mask, type);

	else { /* page is swapcache/shmem */