Re: [Xen-users] unexpected Out Of Memory (OOM)

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-08-07 at 13:17 +0200, Olivier Bonvalet wrote:

> name          = 'reto'
> vcpus         = 1
> maxvcpus      = 8
> memory                = 8192
> vif           = [ 'mac=0e:00:00:00:8e:70,bridge=vlan' ]
> disk          = [ 
>                   '/dev/rbd/sas3copies/reto-root,,xvda,w',
>                   '/dev/rbd/sas3copies/reto-home,,xvdb,w',
>                   '/dev/rbd/sas3copies/reto-var,,xvdc,w',
>                   '/dev/rbd/sas3copies/reto-mysql,,xvdd,w',
>                   '/dev/rbd/sas3copies/reto-exim,,xvde,w',
> 
>                 '/dev/loop1,raw,xvdy,r',
>                 '/dev/loop2,raw,xvdz,r' ]
> kernel                = '/etc/xen/kernels/reto/vmlinuz'
> ramdisk               = '/etc/xen/kernels/reto/initrd.img'
> root          = '/dev/xvda ro rootfstype=ext4'
> extra         = 'panic=60'

All looks pretty normal.

> Then the console :
> 
> Parsing config from /etc/xen/reto.cfg
> Daemon running with PID 20283
> [    0.000000] Initializing cgroup subsys cpu
> [    0.000000] Linux version 2.6.50-dae-xen (root@yiu) (gcc version 4.8.1 
> (Debian 4.8.1-8) ) #2 SMP Sun Aug 4 22:42:05 CEST 2013
> [    0.000000] Command line: root=/dev/xvda ro rootfstype=ext4 panic=60
> [    0.000000] KERNEL supported cpus:
> [    0.000000]   Intel GenuineIntel
> [    0.000000] ACPI in unprivileged domain disabled
> [    0.000000] e820: BIOS-provided physical RAM map:
> [    0.000000] Xen: [mem 0x0000000000000000-0x000000000009ffff] usable
> [    0.000000] Xen: [mem 0x00000000000a0000-0x00000000000fffff] reserved
> [    0.000000] Xen: [mem 0x0000000000100000-0x00000001ffffffff] usable

This all looks good.

> [    1.776382] blkfront: xvdb: barrier or flush: disabled using persistent 
> grants
> [    1.797557]  xvdb: unknown partition table
> [    1.798526] blkfront: xvdc: barrier or flush: disabled using persistent 
> grants
> [    1.820815]  xvdc: unknown partition table
> [    1.822259] blkfront: xvdd: barrier or flush: disabled using persistent 
> grants
> [    1.853766]  xvdd: unknown partition table
> [    1.854749] blkfront: xvde: barrier or flush: disabled using persistent 
> grants
> [    1.857572]  xvde: unknown partition table
> [    1.858010] Setting capacity to 2097152
> [    1.858018] xvda: detected capacity change from 0 to 1073741824
> [    1.858760] blkfront: xvdy: flush diskcache: enabled using persistent 
> grants
> [    1.860885]  xvdy: unknown partition table
> [    1.861913] blkfront: xvdz: flush diskcache: enabled using persistent 
> grants
> [    1.863770]  xvdz: unknown partition table

I know persistent grants have a fixed memory overhead, not sure if that
is on the back or frontend though. Roger?

is there any way to disable persistent grants manually for testing
purposes?

> [    8.595343] zram: module is from the staging directory, the quality is 
> unknown, you have been warned.
> [    8.596003] zram: Created 1 device(s) ...

My first thought was that there was a memory leak in the kernel
somewhere, but staging drivers doing "magic" things with memory make me
nervous. Can you try without zram to rule it out please?

Ian.


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