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 <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Wanpeng Li <[email protected]>
Cc: Mel Gorman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Johannes Weiner 2012-07-31 16:45:40 -07:00 • committed by Linus Torvalds
commit 24467cacc0

View file

@ -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 */