linux-kernel - Re: getting oom/stalls for ltp test cpuset01 with latest/4.9 kernel

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Message-ID: <45ed555a-c6a3-fc8e-1e87-c347c8ed086b@suse.cz>
Date:   Thu, 12 Jan 2017 12:10:00 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Michal Hocko <mhocko@...nel.org>,
        Ganapatrao Kulkarni <gpkulkarni@...il.com>
Cc:     linux-mm@...ck.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: getting oom/stalls for ltp test cpuset01 with latest/4.9 kernel

On 01/11/2017 05:46 PM, Michal Hocko wrote:
> On Wed 11-01-17 21:52:29, Ganapatrao Kulkarni wrote:
>
>> [ 2398.169391] Node 1 Normal: 951*4kB (UME) 1308*8kB (UME) 1034*16kB (UME) 742*32kB (UME) 581*64kB (UME) 450*128kB (UME) 362*256kB (UME) 275*512kB (ME) 189*1024kB (UM) 117*2048kB (ME) 2742*4096kB (M) = 12047196kB
>
> Most of the memblocks are marked Unmovable (except for the 4MB bloks)

No, UME here means that e.g. 4kB blocks are available on unmovable, movable and 
reclaimable lists.

> which shouldn't matter because we can fallback to unmovable blocks for
> movable allocation AFAIR so we shouldn't really fail the request. I
> really fail to see what is going on there but it smells really
> suspicious.

Perhaps there's something wrong with zonelists and we are skipping the Node 1 
Normal zone. Or there's some race with cpuset operations (but can't see how).

The question is, how reproducible is this? And what exactly the test cpuset01 
does? Is it doing multiple things in a loop that could be reduced to a single 
testcase?