mm: memcg: remove needless !mm fixup to init_mm when charging (24467cac) · Commits · 戴 / test

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:

Johannes Weiner <hannes@cmpxchg.org> Acked-by:

KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by:

Michal 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:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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 */

Admin message