[PATCH] memcg: fix oops in mem_cgroup_shrink_usage

[PATCH] memcg: fix oops in mem_cgroup_shrink_usage

[Hugh Dickins]

Got an oops in mem_cgroup_shrink_usage() when testing loop over tmpfs:
yes, of course, loop0 has no mm: other entry points check but this didn't.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
---

 mm/memcontrol.c |    2 ++
 1 file changed, 2 insertions(+)

--- 2.6.27-rc2/mm/memcontrol.c	2008-08-06 08:36:20.000000000 +0100
+++ linux/mm/memcontrol.c	2008-08-06 09:05:26.000000000 +0100
@@ -796,6 +796,8 @@ int mem_cgroup_shrink_usage(struct mm_st
 
 	if (mem_cgroup_subsys.disabled)
 		return 0;
+	if (!mm)
+		return 0;
 
 	rcu_read_lock();
 	mem = mem_cgroup_from_task(rcu_dereference(mm->owner));

Re: [PATCH] memcg: fix oops in mem_cgroup_shrink_usage

[kamezawa.hiroyu]

----- Original Message -----
>Date: 	Wed, 6 Aug 2008 15:15:08 +0100 (BST)
>From: Hugh Dickins <hugh@veritas.com>
>To: Andrew Morton <akpm@linux-foundation.org>
>cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
>   Balbir Singh <balbir@linux.vnet.ibm.com>, linux-kernel@vger.kernel.org
>Subject: [PATCH] memcg: fix oops in mem_cgroup_shrink_usage
>
>
>Got an oops in mem_cgroup_shrink_usage() when testing loop over tmpfs:
>yes, of course, loop0 has no mm: other entry points check but this didn't.
>
>Signed-off-by: Hugh Dickins <hugh@veritas.com>

Ahh, thank you!

-Kame

>---
>
> mm/memcontrol.c |    2 ++
> 1 file changed, 2 insertions(+)
>
>--- 2.6.27-rc2/mm/memcontrol.c	2008-08-06 08:36:20.000000000 +0100
>+++ linux/mm/memcontrol.c	2008-08-06 09:05:26.000000000 +0100
>@@ -796,6 +796,8 @@ int mem_cgroup_shrink_usage(struct mm_st
> 
> 	if (mem_cgroup_subsys.disabled)
> 		return 0;
>+	if (!mm)
>+		return 0;
> 
> 	rcu_read_lock();
> 	mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
>--
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Re: [PATCH] memcg: fix oops in mem_cgroup_shrink_usage

[Balbir Singh]

Hugh Dickins wrote:
> Got an oops in mem_cgroup_shrink_usage() when testing loop over tmpfs:
> yes, of course, loop0 has no mm: other entry points check but this didn't.
> 
> Signed-off-by: Hugh Dickins <hugh@veritas.com>
> ---
> 
>  mm/memcontrol.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> --- 2.6.27-rc2/mm/memcontrol.c	2008-08-06 08:36:20.000000000 +0100
> +++ linux/mm/memcontrol.c	2008-08-06 09:05:26.000000000 +0100
> @@ -796,6 +796,8 @@ int mem_cgroup_shrink_usage(struct mm_st
> 
>  	if (mem_cgroup_subsys.disabled)
>  		return 0;
> +	if (!mm)
> +		return 0;
> 
>  	rcu_read_lock();
>  	mem = mem_cgroup_from_task(rcu_dereference(mm->owner));

Looks good

Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>



-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL