Eric Lee / linux-smarc-t335x-v3.2

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Commit c0bd3f63ce01a1757dbce6373122a05fbf99ced7

Authored by Daisuke Nishimura
Committed by Linus Torvalds
1 parent 1e50cc9022
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

memcg: fix try_get_mem_cgroup_from_swapcache() 

This is a bugfix for commit 3c776e64660028236313f0e54f3a9945764422df
("memcg: charge swapcache to proper memcg").

Used bit of swapcache is solid under page lock, but considering
move_account, pc->mem_cgroup is not.

We need lock_page_cgroup() anyway.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 2 additions and 3 deletions Side-by-side Diff

... ... @@ -1024,9 +1024,7 @@
1024 1024 return NULL;
1025 1025  
1026 1026 pc = lookup_page_cgroup(page);
1027   - /*
1028   - * Used bit of swapcache is solid under page lock.
1029   - */
  1027 + lock_page_cgroup(pc);
1030 1028 if (PageCgroupUsed(pc)) {
1031 1029 mem = pc->mem_cgroup;
1032 1030 if (mem && !css_tryget(&mem->css))
... ... @@ -1040,6 +1038,7 @@
1040 1038 mem = NULL;
1041 1039 rcu_read_unlock();
1042 1040 }
  1041 + unlock_page_cgroup(pc);
1043 1042 return mem;
1044 1043 }
1045 1044