Re: OOM killer invoked on 2.6.20.3, need help understanding why

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

On Mon, 2007-10-01 at 08:57 -0700, david@lang.hm wrote:
> I have a dual dual-core Opteron box running a 32 bit 2.6.20.3 kernel with 
> 4G himem (16G in the box) serving as a iptables firewall. I's got E1000 
> network cards and a LSI raid controller.

OOh, 64bit machine. Seems like a good idea to run a 64bit kernel on
it :-)

> this morning it died with the message 'kernel panic, out of memory and no 
> process to kill'
> 
> gong back through it's syslogs I've got quite a few logs, but I need help 
> in understanding what went wrong (and if it's preventable)
> 
> the process that was running and triggered the OOM is a script
> 
> #!/bin/bash
> 
> PATH=$PATH:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin
> 
> while :
> do
>    logger -t maxconns `cat /proc/sys/net/ipv4/netfilter/ip_conntrack_count`
>    logger -t afdslog `cat /proc/sys/fs/file-nr |awk '{print $1}'`
> 
>    sleep 5
> done
> 
> since the box is a dedicated firewall there is very little running on it 
> (a few other monitoring scripts like this)
> 
> the conntrack count that was being reported was relativly low (around 
> 34k, the max is set at 1m)
> 
> if I'm reading the logs correctly it looks like it ran out of lowmem, but 
> had a lot of himem still available. but I don't know what would have eaten 
> up the lowmem.
> 
> now the logs and other info
> 
> Oct  1 06:01:04 g1a-c maxconns: 34317
> Oct  1 06:01:05 g1a-c kernel: printk: 1887 messages suppressed.
> Oct  1 06:01:05 g1a-c kernel: maxconns invoked oom-killer: gfp_mask=0x84d0, order=0, oomkilladj=0
> Oct  1 06:01:05 g1a-c kernel:  [<c0147850>] out_of_memory+0x100/0x130
> Oct  1 06:01:05 g1a-c kernel:  [<c0148b2b>] __alloc_pages+0x22b/0x2d0
> Oct  1 06:01:05 g1a-c kernel:  [<c01135b1>] pte_alloc_one+0x11/0x20
> Oct  1 06:01:05 g1a-c kernel:  [<c014feaa>] __pte_alloc+0x1a/0xb0
> Oct  1 06:01:05 g1a-c kernel:  [<c0150369>] copy_pte_range+0x289/0x2b0
> Oct  1 06:01:05 g1a-c kernel:  [<c01504b9>] copy_page_range+0x129/0x170
> Oct  1 06:01:05 g1a-c kernel:  [<c011e024>] dup_mm+0x214/0x2e0
> Oct  1 06:01:05 g1a-c kernel:  [<c011e179>] copy_mm+0x89/0xa0
> Oct  1 06:01:05 g1a-c kernel:  [<c011e91a>] copy_process+0x33a/0xc60
> Oct  1 06:01:05 g1a-c kernel:  [<c011f2a5>] do_fork+0x65/0x1f0
> Oct  1 06:01:05 g1a-c kernel:  [<c027e2c2>] copy_to_user+0x32/0x50
> Oct  1 06:01:05 g1a-c kernel:  [<c0101722>] sys_clone+0x32/0x40
> Oct  1 06:01:05 g1a-c kernel:  [<c0102a8e>] syscall_call+0x7/0xb
> Oct  1 06:01:05 g1a-c kernel:  =======================
> Oct  1 06:01:05 g1a-c kernel: Mem-info:
> Oct  1 06:01:05 g1a-c kernel: DMA per-cpu:
> Oct  1 06:01:05 g1a-c kernel: CPU    0: Hot: hi:    0, btch:   1 usd:   0   Cold: hi:    0, btch:   1 usd:   0
> Oct  1 06:01:05 g1a-c kernel: CPU    1: Hot: hi:    0, btch:   1 usd:   0   Cold: hi:    0, btch:   1 usd:   0
> Oct  1 06:01:05 g1a-c kernel: CPU    2: Hot: hi:    0, btch:   1 usd:   0   Cold: hi:    0, btch:   1 usd:   0
> Oct  1 06:01:05 g1a-c kernel: CPU    3: Hot: hi:    0, btch:   1 usd:   0   Cold: hi:    0, btch:   1 usd:   0
> Oct  1 06:01:05 g1a-c kernel: Normal per-cpu:
> Oct  1 06:01:05 g1a-c kernel: CPU    0: Hot: hi:  186, btch:  31 usd: 104   Cold: hi:   62, btch:  15 usd:  58
> Oct  1 06:01:05 g1a-c kernel: CPU    1: Hot: hi:  186, btch:  31 usd:  22   Cold: hi:   62, btch:  15 usd:  52
> Oct  1 06:01:05 g1a-c kernel: CPU    2: Hot: hi:  186, btch:  31 usd:  30   Cold: hi:   62, btch:  15 usd:  58
> Oct  1 06:01:05 g1a-c kernel: CPU    3: Hot: hi:  186, btch:  31 usd:  15   Cold: hi:   62, btch:  15 usd:  60
> Oct  1 06:01:05 g1a-c kernel: HighMem per-cpu:
> Oct  1 06:01:05 g1a-c kernel: CPU    0: Hot: hi:  186, btch:  31 usd: 105   Cold: hi:   62, btch:  15 usd:   8
> Oct  1 06:01:05 g1a-c kernel: CPU    1: Hot: hi:  186, btch:  31 usd:  51   Cold: hi:   62, btch:  15 usd:   3
> Oct  1 06:01:05 g1a-c kernel: CPU    2: Hot: hi:  186, btch:  31 usd: 122   Cold: hi:   62, btch:  15 usd:   0
> Oct  1 06:01:05 g1a-c kernel: CPU    3: Hot: hi:  186, btch:  31 usd:  42   Cold: hi:   62, btch:  15 usd:   0
> Oct  1 06:01:05 g1a-c kernel: Active:3496 inactive:616 dirty:16 writeback:0 unstable:0
> Oct  1 06:01:05 g1a-c kernel:  free:3941515 slab:6779 mapped:843 pagetables:48 bounce:0
> Oct  1 06:01:05 g1a-c kernel: DMA free:3548kB min:68kB low:84kB high:100kB active:16kB inactive:0kB present:16256kB pages_scanned:56 all_unreclaimable? yes
> Oct  1 06:01:05 g1a-c kernel: lowmem_reserve[]: 0 873 16240
> Oct  1 06:01:05 g1a-c kernel: Normal free:3640kB min:3744kB low:4680kB high:5616kB active:148kB inactive:0kB present:894080kB pages_scanned:7196 all_unreclaimable? yes
> Oct  1 06:01:05 g1a-c kernel: lowmem_reserve[]: 0 0 122936
> Oct  1 06:01:05 g1a-c kernel: HighMem free:15758872kB min:512kB low:17000kB high:33492kB active:13820kB inactive:2464kB present:15735808kB pages_scanned:0 all_unreclaimable? no
> Oct  1 06:01:05 g1a-c kernel: lowmem_reserve[]: 0 0 0
> Oct  1 06:01:05 g1a-c kernel: DMA: 3*4kB 2*8kB 1*16kB 1*32kB 0*64kB 1*128kB 1*256kB 0*512kB 1*1024kB 1*2048kB 0*4096kB = 3532kB
> Oct  1 06:01:05 g1a-c kernel: Normal: 0*4kB 23*8kB 6*16kB 1*32kB 0*64kB 0*128kB 1*256kB 0*512kB 1*1024kB 1*2048kB 0*4096kB = 3640kB
> Oct  1 06:01:05 g1a-c kernel: HighMem: 122*4kB 658*8kB 622*16kB 464*32kB 391*64kB 336*128kB 277*256kB 226*512kB 169*1024kB 135*2048kB 3668*4096kB = 15758872kB
> Oct  1 06:01:05 g1a-c kernel: Swap cache: add 0, delete 0, find 0/0, race 0+0
> Oct  1 06:01:05 g1a-c kernel: Free swap  = 2048276kB
> Oct  1 06:01:05 g1a-c kernel: Total swap = 2048276kB
> Oct  1 06:01:05 g1a-c kernel: Free swap:       2048276kB

Seems like it ran out of memory in zone normal. Looks like it all went to SLAB.
Could you run your regular workload, and append /proc/slabinfo onto a file every 5 minutes or so?

That should tell us who is using all this memory. (assuming it reproduces...)

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