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Date: Wed, 12 May 2010 14:16:42 +0800
From: Miao Xie <miaox@cn.fujitsu.com>
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To: Andrew Morton <akpm@linux-foundation.org>
CC: David Rientjes <rientjes@google.com>, Nick Piggin <npiggin@suse.de>,
       Paul Menage <menage@google.com>,
       Lee Schermerhorn <lee.schermerhorn@hp.com>,
       Linux-Kernel <linux-kernel@vger.kernel.org>,
       Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH 2/2] cpuset,mm: fix no node to alloc memory when changing
 cpuset's mems
References: <4BDFFCCA.3020906@cn.fujitsu.com> <20100511184900.8211b6f9.akpm@linux-foundation.org>
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on 2010-5-12 9:49, Andrew Morton wrote:
...
>> --- a/kernel/exit.c
>> +++ b/kernel/exit.c
>> @@ -16,6 +16,7 @@
>>  #include <linux/key.h>
>>  #include <linux/security.h>
>>  #include <linux/cpu.h>
>> +#include <linux/cpuset.h>
>>  #include <linux/acct.h>
>>  #include <linux/tsacct_kern.h>
>>  #include <linux/file.h>
>> @@ -1003,8 +1004,10 @@ NORET_TYPE void do_exit(long code)
>>  
>>  	exit_notify(tsk, group_dead);
>>  #ifdef CONFIG_NUMA
>> +	task_lock(tsk);
>>  	mpol_put(tsk->mempolicy);
>>  	tsk->mempolicy = NULL;
>> +	task_unlock(tsk);
>>  #endif
>>  #ifdef CONFIG_FUTEX
>>  	if (unlikely(current->pi_state_cache))
> 
> Given that this function is already holding task_lock(tsk), this
> didn't work very well.

Sorry for replying late.

Thanks for your patch that removes task_lock(tsk).

I made this patch against the mainline tree, and do_exit() in the mainline tree
doesn't hold task_lock(tsk), so I took task_lock(tsk). But I didn't take notice
that do_exit() in the mmotm tree had been changed, and I made this mistake.

> Also, why was the inclusion of cpuset.h added?  Nothing which this
> patch adds appears to need it?
> 

This is my mistake, I will make patch to cleanup it.

Thanks!
Miao