Re: [PATCH] cpuset: fix allocating page cache/slab object on the unallowed node when memory spread is set

[Miao Xie <miaox@cn.fujitsu.com>]

on 2009-1-28 6:42 Andrew Morton wrote:
> On Wed, 21 Jan 2009 16:06:20 +0800
> Miao Xie <miaox@cn.fujitsu.com> wrote:
> 
>> The task still allocated the page caches on old node after modifying its
>> cpuset's mems when 'memory_spread_page' was set, it is caused by the old
>> mem_allowed_list of the task, the current kernel doesn't updates it unless some
>> function invokes cpuset_update_task_memory_state(), it is too late sometimes.
>> We must update the mem_allowed_list of the tasks in time.
>>
>> Slab has the same problem.
>>
>> We fixes the bug by updating tasks' mem_allowed_list and spread flag after
>> its cpuset's mems or spread flag is changed.
>>
>>
>> ...
>>
>> --- a/kernel/kthread.c
>> +++ b/kernel/kthread.c
>> @@ -242,6 +242,7 @@ int kthreadd(void *unused)
>>  	set_user_nice(tsk, KTHREAD_NICE_LEVEL);
>>  	set_cpus_allowed_ptr(tsk, CPU_MASK_ALL_PTR);
>>  
>> +	current->mems_allowed = node_possible_map;
>>  	current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG;
> 
> Why this change?  kthreadd() is called from rest_init(), before anyone
> has had a chance to alter ->mems_allowed?

I found that after mems_allowed of kthreadd was not initialized applying this patch,
every bit of it is 1, so...
Maybe it is redundant.

Thanks!
Miao

> 
> I queued the patch pending your response to Paul's questions, thanks.
> 
> 
>