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From: Sasha Levin <sasha.levin@oracle.com>
To: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Petr Holasek <pholasek@redhat.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] ksm: make rmap walks more scalable
Date: Thu, 20 Dec 2012 17:43:11 -0500	[thread overview]
Message-ID: <50D3947F.2060503@oracle.com> (raw)
In-Reply-To: <alpine.LNX.2.00.1212201409170.977@eggly.anvils>

On 12/20/2012 05:37 PM, Hugh Dickins wrote:
> On Thu, 20 Dec 2012, Sasha Levin wrote:
>> On 12/19/2012 08:44 PM, Hugh Dickins wrote:
>>> The rmap walks in ksm.c are like those in rmap.c:
>>> they can safely be done with anon_vma_lock_read().
>>>
>>> Signed-off-by: Hugh Dickins <hughd@google.com>
>>> ---
>>
>> Hi Hugh,
>>
>> This patch didn't fix the ksm oopses I'm seeing.
> 
> I wouldn't expect it to (and should certainly have mentioned oopses
> in the commit message if I'd intended): this patch was merely an
> optimization/clarification of a commit gone in for 3.8-rc1.
> 
> Understandable misunderstanding: you took my Cc too seriously,
> I just thought I'd better keep Petr in the loop on current changes
> to ksm.c, and foolishly kept you in too ;)
> 
> Your oopses are on linux-next, which as of 20121220 still had Petr's
> nice but buggy NUMA KSM patch in: it should go away when Stephen gets
> a fresh mm update from Andrew, then reappear once his v6 goes into mm.
> 
> To stop these oopses in get_mergeable_page (inlined in
> unstable_tree_search_insert) you need the patch I showed on
> Tuesday, which I hope he'll merge in for his v6.  That doesn't fix
> all of the problems, but hopefully all that you'll encounter before
> I've devised a fix for the separate stale stable_nodes issue.

My bad! I thought that this is the finalized version of the patch from
Tuesday and was surprised when the oops was still there :)

fwiw I'll use this to report that I'm not seeing any unexpected behaviour
with this patch applied.


Thanks,
Sasha

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  reply	other threads:[~2012-12-20 22:43 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-20  1:42 [PATCH] sched: numa: ksm: fix oops in task_numa_placment() Hugh Dickins
2012-12-20  1:44 ` [PATCH] ksm: make rmap walks more scalable Hugh Dickins
2012-12-20 11:17   ` Mel Gorman
2012-12-20 21:49   ` Sasha Levin
2012-12-20 22:26     ` Linus Torvalds
2012-12-20 22:40       ` Hugh Dickins
2012-12-20 22:37     ` Hugh Dickins
2012-12-20 22:43       ` Sasha Levin [this message]
2012-12-21  0:36         ` Petr Holasek
2012-12-21  2:35           ` Hugh Dickins
2012-12-20 11:14 ` [PATCH] sched: numa: ksm: fix oops in task_numa_placment() Mel Gorman

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