[PATCH] mm/memcg: add BUG() to mem_cgroup_reset

[PATCH] mm/memcg: add BUG() to mem_cgroup_reset

[Wanpeng Li]

From: Wanpeng Li <liwp@linux.vnet.ibm.com>

Branch in mem_cgroup_reset only can be RES_MAX_USAGE, RES_FAILCNT.

Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
---
 mm/memcontrol.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a501660..5e4d1ab 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3976,6 +3976,8 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
 		else
 			res_counter_reset_failcnt(&memcg->memsw);
 		break;
+	default:
+		BUG();
 	}
 
 	return 0;
-- 
1.7.5.4

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Re: [PATCH] mm/memcg: add BUG() to mem_cgroup_reset

[Gavin Shan]

On Fri, Jul 06, 2012 at 11:44:57AM +0800, Wanpeng Li wrote:
>From: Wanpeng Li <liwp@linux.vnet.ibm.com>
>
>Branch in mem_cgroup_reset only can be RES_MAX_USAGE, RES_FAILCNT.
>
>Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
>---
> mm/memcontrol.c |    2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
>diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>index a501660..5e4d1ab 100644
>--- a/mm/memcontrol.c
>+++ b/mm/memcontrol.c
>@@ -3976,6 +3976,8 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
> 		else
> 			res_counter_reset_failcnt(&memcg->memsw);
> 		break;
>+	default:
>+		BUG();

It might be not convinced to have "BUG()" here. You might add
something for debugging purpose. For example,
	default:
		printk(KERN_WARNING "%s: Unrecognized name %d\n",
			__func__, name);

Thanks,
Gavin
 
> 	}
>
> 	return 0;
>-- 
>1.7.5.4
>
>--
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Re: [PATCH] mm/memcg: add BUG() to mem_cgroup_reset

[Wanpeng Li]

On Fri, Jul 06, 2012 at 01:19:16PM +0800, Gavin Shan wrote:
>On Fri, Jul 06, 2012 at 11:44:57AM +0800, Wanpeng Li wrote:
>>From: Wanpeng Li <liwp@linux.vnet.ibm.com>
>>
>>Branch in mem_cgroup_reset only can be RES_MAX_USAGE, RES_FAILCNT.
>>
>>Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
>>---
>> mm/memcontrol.c |    2 ++
>> 1 files changed, 2 insertions(+), 0 deletions(-)
>>
>>diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>>index a501660..5e4d1ab 100644
>>--- a/mm/memcontrol.c
>>+++ b/mm/memcontrol.c
>>@@ -3976,6 +3976,8 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
>> 		else
>> 			res_counter_reset_failcnt(&memcg->memsw);
>> 		break;
>>+	default:
>>+		BUG();
>
>It might be not convinced to have "BUG()" here. You might add
>something for debugging purpose. For example,
>	default:
>		printk(KERN_WARNING "%s: Unrecognized name %d\n",
>			__func__, name);

But many funtions in mm/memcontrol.c use BUG(), if the branch is not
present. 

Regards,
Wanpeng Li

>
>Thanks,
>Gavin
> 
>> 	}
>>
>> 	return 0;
>>-- 
>>1.7.5.4
>>
>>--
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>>the body to majordomo@kvack.org.  For more info on Linux MM,
>>see: http://www.linux-mm.org/ .
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>>
>
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Re: [PATCH] mm/memcg: add BUG() to mem_cgroup_reset

[Johannes Weiner]

On Fri, Jul 06, 2012 at 11:44:57AM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <liwp@linux.vnet.ibm.com>
> 
> Branch in mem_cgroup_reset only can be RES_MAX_USAGE, RES_FAILCNT.

And nobody is passing anything else.  Which is easy to prove as this
is a private function.  And there wouldn't even be any harm passing
something else.  Please don't add stuff like this.

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Re: [PATCH] mm/memcg: add BUG() to mem_cgroup_reset

[Wanpeng Li]

On Fri, Jul 06, 2012 at 10:22:42AM +0200, Johannes Weiner wrote:
>On Fri, Jul 06, 2012 at 11:44:57AM +0800, Wanpeng Li wrote:
>> From: Wanpeng Li <liwp@linux.vnet.ibm.com>
>> 
>> Branch in mem_cgroup_reset only can be RES_MAX_USAGE, RES_FAILCNT.
>
>And nobody is passing anything else.  Which is easy to prove as this
>is a private function.  And there wouldn't even be any harm passing
>something else.  Please don't add stuff like this.

Ok, thank you for your comment.

I also have another two patches, title:

clarify type in memory cgroups
return -EBUSY when oom-kill-disable modified and memcg use_hierarchy, has children

Hopefully, you can review. Thank you Johannes! :-)

Regards,
Wanpeng Li 

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