From: Johannes Weiner <hannes@cmpxchg.org>
Date: Tue, 31 Jul 2012 23:45:28 +0000 (-0700)
Subject: mm: swapfile: clean up unuse_pte race handling
X-Git-Tag: Ubuntu-snapdragon-4.4.0-1050.54~14299^2~23
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=5d84c7766e8aacc6e3477bdf02fdb417163cf89b;p=mirror_ubuntu-artful-kernel.git

mm: swapfile: clean up unuse_pte race handling

The conditional mem_cgroup_cancel_charge_swapin() is a leftover from when
the function would continue to reestablish the page even after
mem_cgroup_try_charge_swapin() failed.  After 85d9fc8 "memcg: fix refcnt
handling at swapoff", the condition is always true when this code is
reached.

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: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
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>
---

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 63958d60ecb0..14e254c768fc 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -835,8 +835,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 
 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
-		if (ret > 0)
-			mem_cgroup_cancel_charge_swapin(memcg);
+		mem_cgroup_cancel_charge_swapin(memcg);
 		ret = 0;
 		goto out;
 	}