[DRBD-user] Re: Daily crashes with a XFS filesystem on a DRBD 0.7.5 device with 2.6 SMP kernel

Philipp Reisner philipp.reisner at linbit.com
Thu Nov 11 11:43:04 CET 2004


On Thursday 11 November 2004 11:22, Cyril Bouthors wrote:
> On 11 Nov 2004, cyril at bouthors.org wrote:
> > The machine stop responding to ICMP requests after ~20 seconds; the
> > same runs just fine if I use an UP kernel.
>
> I've just seen that the kernel said that during the last "make -j"
> crash on the SMP kernel:
>
> Nov 11 10:49:26 filer2 kernel: sh: page allocation failure. order:0,
> mode:0x50 Nov 11 10:49:26 filer2 kernel:  [__alloc_pages+450/880]
[...]
>
> I'm not a kernel hacker but it looks like an XFS problem :)
>
> Please let me know if it has nothing to do with DRBD.

I would put it that way:

1st, it is an XFS bug. Because XFS does not handle the failure of 
     a memory allocation at in a specific situation.
     -> A serious filesystem has to deal with such situations 
        more gracefully.

2nd, DRBD makes the situation not better, since it causes network 
     load during high disk-IO situations, but well, that is the 
     purpose of DRBD, it is not a bug. 

It is interesting that XFS survives the same memory pressure in an
UP kernel, I guess it is a realy subtile bug in XFS...

-philipp
-- 
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