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Commit 24467cacc03cf8b156d4c6786697e5e5d13c9321

Authored by Johannes Weiner
Committed by Linus Torvalds
1 parent 62ba7442c8
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

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: 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>

Showing 1 changed file with 1 additions and 6 deletions Side-by-side Diff

... ... @@ -2333,7 +2333,7 @@
2333 2333 * We always charge the cgroup the mm_struct belongs to.
2334 2334 * The mm_struct's mem_cgroup changes on task migration if the
2335 2335 * thread group leader migrates. It's possible that mm is not
2336   - * set, if so charge the init_mm (happens for pagecache usage).
  2336 + * set, if so charge the root memcg (happens for pagecache usage).
2337 2337 */
2338 2338 if (!*ptr && !mm)
2339 2339 *ptr = root_mem_cgroup;
... ... @@ -2833,8 +2833,6 @@
2833 2833 ret = 0;
2834 2834 return ret;
2835 2835 charge_cur_mm:
2836   - if (unlikely(!mm))
2837   - mm = &init_mm;
2838 2836 ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);
2839 2837 if (ret == -EINTR)
2840 2838 ret = 0;
... ... @@ -2898,9 +2896,6 @@
2898 2896 return 0;
2899 2897 if (PageCompound(page))
2900 2898 return 0;
2901   -
2902   - if (unlikely(!mm))
2903   - mm = &init_mm;
2904 2899  
2905 2900 if (!PageSwapCache(page))
2906 2901 ret = mem_cgroup_charge_common(page, mm, gfp_mask, type);