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@xxxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
---
mm/memcontrol.c | 7 +------
1 files changed, 1 insertions(+), 6 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2c7d164c..c6bcaaa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2334,7 +2334,7 @@ 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;
@@ -2834,8 +2834,6 @@ 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;
@@ -2900,9 +2898,6 @@ 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 */
--
1.7.7.6
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