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Message-ID: <20200527120549.GA741@lca.pw>
Date: Wed, 27 May 2020 08:05:49 -0400
From: Qian Cai <cai@....pw>
To: Feng Tang <feng.tang@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Michal Hocko <mhocko@...e.com>,
Johannes Weiner <hannes@...xchg.org>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Matthew Wilcox <willy@...radead.org>,
Mel Gorman <mgorman@...e.de>,
Kees Cook <keescook@...omium.org>,
Luis Chamberlain <mcgrof@...nel.org>,
Iurii Zaikin <yzaikin@...gle.com>, andi.kleen@...el.com,
tim.c.chen@...el.com, dave.hansen@...el.com, ying.huang@...el.com,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] make vm_committed_as_batch aware of vm overcommit
policy
On Wed, May 27, 2020 at 06:46:06PM +0800, Feng Tang wrote:
> Hi Qian,
>
> On Tue, May 26, 2020 at 10:25:39PM -0400, Qian Cai wrote:
> > > > > > [1] https://lkml.org/lkml/2020/3/5/57
> > > > >
> > > > > Reverted this series fixed a warning under memory pressue.
> > > >
> > > > Andrew, Stephen, can you drop this series?
> > > >
> > > > >
> > > > > [ 3319.257898] LTP: starting oom01
> > > > > [ 3319.284417] ------------[ cut here ]------------
> > > > > [ 3319.284439] memory commitment underflow
> > >
> > > Thanks for the catch!
> > >
> > > Could you share the info about the platform, like the CPU numbers
> > > and RAM size, and what's the mmap test size of your test program.
> > > It would be great if you can point me the link to the test program.
> >
> > I have been reproduced this on both AMD and Intel. The test just
> > allocating memory and swapping.
> >
> > https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/oom/oom01.c
> > https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/tunable/overcommit_memory.c
> >
> > It might be better to run the whole LTP mm tests if none of the above
> > triggers it for you which has quite a few memory pressurers.
> >
> > /opt/ltp/runltp -f mm
>
> Thanks for sharing. I tried to reproduce this on 2 server plaforms,
> but can't reproduce it, and they are still under testing.
>
> Meanwhile, could you help to try the below patch, which is based on
> Andi's suggestion and have some debug info. The warning is a little
> strange, as the condition is
>
> (percpu_counter_read(&vm_committed_as) <
> -(s64)vm_committed_as_batch * num_online_cpus())
>
> while for your platform (48 CPU + 128 GB RAM), the
> '-(s64)vm_committed_as_batch * num_online_cpus()'
> is a s64 value: '-32G', which makes the condition hard to be true,
> and when it is, it could be triggered by some magic for s32/s64
> operations around the percpu-counter.
Here is the information on AMD and powerpc below affected by this. It
could need a bit patient to reproduce, but our usual daily CI would
trigger it eventually after a few tries.
# git clone https://github.com/cailca/linux-mm.git
# cd linux-mm
# ./compile.sh
# systemctl reboot
# ./test.sh
== AMD ==
# lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 128
On-line CPU(s) list: 0-127
Thread(s) per core: 2
Core(s) per socket: 32
Socket(s): 2
NUMA node(s): 8
Vendor ID: AuthenticAMD
CPU family: 23
Model: 1
Model name: AMD EPYC 7601 32-Core Processor
Stepping: 2
CPU MHz: 3184.974
CPU max MHz: 2200.0000
CPU min MHz: 1200.0000
BogoMIPS: 4391.87
Virtualization: AMD-V
L1d cache: 32K
L1i cache: 64K
L2 cache: 512K
L3 cache: 8192K
NUMA node0 CPU(s): 0-7,64-71
NUMA node1 CPU(s): 8-15,72-79
NUMA node2 CPU(s): 16-23,80-87
NUMA node3 CPU(s): 24-31,88-95
NUMA node4 CPU(s): 32-39,96-103
NUMA node5 CPU(s): 40-47,104-111
NUMA node6 CPU(s): 48-55,112-119
NUMA node7 CPU(s): 56-63,120-127
# numactl -H
available: 8 nodes (0-7)
node 0 cpus: 0 1 2 3 4 5 6 7 64 65 66 67 68 69 70 71
node 0 size: 20028 MB
node 0 free: 3837 MB
node 1 cpus: 8 9 10 11 12 13 14 15 72 73 74 75 76 77 78 79
node 1 size: 0 MB
node 1 free: 0 MB
node 2 cpus: 16 17 18 19 20 21 22 23 80 81 82 83 84 85 86 87
node 2 size: 0 MB
node 2 free: 0 MB
node 3 cpus: 24 25 26 27 28 29 30 31 88 89 90 91 92 93 94 95
node 3 size: 0 MB
node 3 free: 0 MB
node 4 cpus: 32 33 34 35 36 37 38 39 96 97 98 99 100 101 102 103
node 4 size: 31391 MB
node 4 free: 21309 MB
node 5 cpus: 40 41 42 43 44 45 46 47 104 105 106 107 108 109 110 111
node 5 size: 0 MB
node 5 free: 0 MB
node 6 cpus: 48 49 50 51 52 53 54 55 112 113 114 115 116 117 118 119
node 6 size: 0 MB
node 6 free: 0 MB
node 7 cpus: 56 57 58 59 60 61 62 63 120 121 122 123 124 125 126 127
node 7 size: 0 MB
node 7 free: 0 MB
node distances:
node 0 1 2 3 4 5 6 7
0: 10 16 16 16 32 32 32 32
1: 16 10 16 16 32 32 32 32
2: 16 16 10 16 32 32 32 32
3: 16 16 16 10 32 32 32 32
4: 32 32 32 32 10 16 16 16
5: 32 32 32 32 16 10 16 16
6: 32 32 32 32 16 16 10 16
7: 32 32 32 32 16 16 16 10
== powerpc ==
# lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 128
On-line CPU(s) list: 0-127
Thread(s) per core: 4
Core(s) per socket: 16
Socket(s): 2
NUMA node(s): 2
Model: 2.2 (pvr 004e 1202)
Model name: POWER9 (raw), altivec supported
CPU max MHz: 3800.0000
CPU min MHz: 2300.0000
L1d cache: 32K
L1i cache: 32K
L2 cache: 512K
L3 cache: 10240K
NUMA node0 CPU(s): 0-63
NUMA node8 CPU(s): 64-127
# numactl -H
available: 2 nodes (0,8)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
node 0 size: 130138 MB
node 0 free: 125654 MB
node 8 cpus: 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127
node 8 size: 130781 MB
node 8 free: 124756 MB
node distances:
node 0 8
0: 10 40
8: 40 10
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