linux-kernel - Re: oom-killer

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Date:   Mon, 5 Aug 2019 14:05:25 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Pankaj Suryawanshi <pankajssuryawanshi@...il.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        pankaj.suryawanshi@...fochips.com
Subject: Re: oom-killer

On Mon 05-08-19 13:56:20, Vlastimil Babka wrote:
> On 8/5/19 1:24 PM, Michal Hocko wrote:
> >> [  727.954355] CPU: 0 PID: 56 Comm: kworker/u8:2 Tainted: P           O  4.14.65 #606
> > [...]
> >> [  728.029390] [<c034a094>] (oom_kill_process) from [<c034af24>] (out_of_memory+0x140/0x368)
> >> [  728.037569]  r10:00000001 r9:c12169bc r8:00000041 r7:c121e680 r6:c1216588 r5:dd347d7c > [  728.045392]  r4:d5737080
> >> [  728.047929] [<c034ade4>] (out_of_memory) from [<c03519ac>]  (__alloc_pages_nodemask+0x1178/0x124c)
> >> [  728.056798]  r7:c141e7d0 r6:c12166a4 r5:00000000 r4:00001155
> >> [  728.062460] [<c0350834>] (__alloc_pages_nodemask) from [<c021e9d4>] (copy_process.part.5+0x114/0x1a28)
> >> [  728.071764]  r10:00000000 r9:dd358000 r8:00000000 r7:c1447e08 r6:c1216588 r5:00808111
> >> [  728.079587]  r4:d1063c00
> >> [  728.082119] [<c021e8c0>] (copy_process.part.5) from [<c0220470>] (_do_fork+0xd0/0x464)
> >> [  728.090034]  r10:00000000 r9:00000000 r8:dd008400 r7:00000000 r6:c1216588 r5:d2d58ac0
> >> [  728.097857]  r4:00808111
> > 
> > The call trace tells that this is a fork (of a usermodhlper but that is
> > not all that important.
> > [...]
> >> [  728.260031] DMA free:17960kB min:16384kB low:25664kB high:29760kB active_anon:3556kB inactive_anon:0kB active_file:280kB inactive_file:28kB unevictable:0kB writepending:0kB present:458752kB managed:422896kB mlocked:0kB kernel_stack:6496kB pagetables:9904kB bounce:0kB free_pcp:348kB local_pcp:0kB free_cma:0kB
> >> [  728.287402] lowmem_reserve[]: 0 0 579 579
> > 
> > So this is the only usable zone and you are close to the min watermark
> > which means that your system is under a serious memory pressure but not
> > yet under OOM for order-0 request. The situation is not great though
> 
> Looking at lowmem_reserve above, wonder if 579 applies here? What does
> /proc/zoneinfo say?

This is GFP_KERNEL request essentially so there shouldn't be any lowmem
reserve here, no?
-- 
Michal Hocko
SUSE Labs