mm/memcontrol.c: fix uninitialized variable use in mem_cgroup_move_parent()
Jesper Juhl [Tue, 25 Jan 2011 23:07:24 +0000 (15:07 -0800)]
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').  The
'put_back' label should be moved below the call to
compound_unlock_irqrestore() as per this patch.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

index db76ef7..4fcf47a 100644 (file)
@@ -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);