+ memcg-fix-refcnt-handling-at-swapoff.patch added to -mm tree

+ memcg-fix-refcnt-handling-at-swapoff.patch added to -mm tree

[akpm]

The patch titled
     memcg: fix refcnt handling at swapoff
has been added to the -mm tree.  Its filename is
     memcg-fix-refcnt-handling-at-swapoff.patch

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See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: memcg: fix refcnt handling at swapoff
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Now, at swapoff, even while try_charge() fails, commit is executed.  This
is a bug which turns the refcnt of cgroup_subsys_state negative.

Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Tested-by: Li Zefan <lizf@cn.fujitsu.com>
Tested-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swapfile.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff -puN mm/swapfile.c~memcg-fix-refcnt-handling-at-swapoff mm/swapfile.c
--- a/mm/swapfile.c~memcg-fix-refcnt-handling-at-swapoff
+++ a/mm/swapfile.c
@@ -698,8 +698,10 @@ static int unuse_pte(struct vm_area_stru
 	pte_t *pte;
 	int ret = 1;
 
-	if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr))
+	if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) {
 		ret = -ENOMEM;
+		goto out_nolock;
+	}
 
 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
@@ -723,6 +725,7 @@ static int unuse_pte(struct vm_area_stru
 	activate_page(page);
 out:
 	pte_unmap_unlock(pte, ptl);
+out_nolock:
 	return ret;
 }
 
_

Patches currently in -mm which might be from kamezawa.hiroyu@jp.fujitsu.com are

origin.patch
cgroups-use-hierarchy-mutex-in-creation-failure-path.patch
memcg-get-put-parents-at-create-free.patch
memcg-get-put-parents-at-create-free-fix.patch
memcg-fix-refcnt-handling-at-swapoff.patch
proc-pid-maps-dont-show-pgoff-of-pure-anon-vmas.patch
proc-pid-maps-dont-show-pgoff-of-pure-anon-vmas-checkpatch-fixes.patch