linux-kernel - Re: [PATCH 2/2] tmpfs: fix mempolicy object leaks

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Date:	Thu, 07 Mar 2013 14:41:29 +0800
From:	Will Huck <will.huckk@...il.com>
To:	Hugh Dickins <hughd@...gle.com>
CC:	Greg Thelen <gthelen@...gle.com>, akpm@...ux-foundation.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] tmpfs: fix mempolicy object leaks

Hi Hugh,
On 03/06/2013 03:40 AM, Hugh Dickins wrote:
> On Mon, 4 Mar 2013, Will Huck wrote:
>> Could you explain me why shmem has more relationship with mempolicy? It seems
>> that there are many codes in shmem handle mempolicy, but other components in
>> mm subsystem just have little.
> NUMA mempolicy is mostly handled in mm/mempolicy.c, which services the
> mbind, migrate_pages, set_mempolicy, get_mempolicy system calls: which
> govern how process memory is distributed across NUMA nodes.
>
> mm/shmem.c is affected because it was also found useful to specify
> mempolicy on the shared memory objects which may back process memory:
> that includes SysV SHM and POSIX shared memory and tmpfs.  mm/hugetlb.c
> contains some mempolicy handling for hugetlbfs; fs/ramfs is kept minimal,
> so nothing in there.
>
> Those are the memory-based filesystems, where NUMA mempolicy is most
> natural.  The regular filesystems could support shared mempolicy too,
> but that would raise more awkward design questions.

I found that if mbind several processes to one node and almost exhaust 
memory, processes will just stuck and no processes make progress or be 
killed. Is it normal?

>
> Hugh

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