linux-kernel - [PATCH] Fix uninitialized variable use in mm/memcontrol.c::mem_cgroup_move

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Message-ID: <alpine.LNX.2.00.1101222044580.7746@swampdragon.chaosbits.net>
Date:	Sat, 22 Jan 2011 20:51:32 +0100 (CET)
From:	Jesper Juhl <jj@...osbits.net>
To:	linux-mm@...ck.org
cc:	linux-kernel@...r.kernel.org,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Pavel Emelianov <xemul@...nvz.org>,
	"Kirill A. Shutemov" <kirill@...temov.name>
Subject: [PATCH] Fix uninitialized variable use in
 mm/memcontrol.c::mem_cgroup_move_parent()

In mm/memcontrol.c::mem_cgroup_move_parent() there's a path that jumps to 
the 'put_back' label
  	ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false, charge);
  	if (ret || !parent)
  		goto put_back;
 where we'll 
  	if (charge > PAGE_SIZE)
  		compound_unlock_irqrestore(page, flags);
but, we have not assigned anything to 'flags' at this point, nor have we 
called 'compound_lock_irqsave()' (which is what sets 'flags').
So, I believe the 'put_back' label should be moved below the call to 
compound_unlock_irqrestore() as per this patch. 

Signed-off-by: Jesper Juhl <jj@...osbits.net>
---
 memcontrol.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

  compile tested only.

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index db76ef7..4fcf47a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2292,9 +2292,10 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
 	ret = mem_cgroup_move_account(pc, child, parent, true, charge);
 	if (ret)
 		mem_cgroup_cancel_charge(parent, charge);
-put_back:
+
 	if (charge > PAGE_SIZE)
 		compound_unlock_irqrestore(page, flags);
+put_back:
 	putback_lru_page(page);
 put:
 	put_page(page);


-- 
Jesper Juhl <jj@...osbits.net>            http://www.chaosbits.net/
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
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