Re: btrfs crash when low on memory.

From: Martin Steigerwald
Date: Wed Feb 27 2013 - 05:28:12 EST

Am Mittwoch, 27. Februar 2013 schrieb Dave Jones:
> Something I've yet to repeat managed to leak a whole bunch of memory
> while I was travelling, and locked up my workstation.
> When I got home, this was the last thing printed out before it locked up
> (it did make it into the logs thankfully) after a bunch of instances of
> the oom-killers handywork.
> SLUB: Unable to allocate memory on node -1 (gfp=0x50)
> cache: btrfs_extent_state, object size: 176, buffer size: 504, default
> order: 1, min order: 0 node 0: slabs: 49, objs: 640, free: 0
> ------------[ cut here ]------------
> kernel BUG at fs/btrfs/extent_io.c:748!

Thank you for reporting this Dave.

I have lockups due to memory pressure conditions on my ThinkPad T520 as well
when playing Planeshift for some time. (AFAIR since I switched my home
directory to BTRFS (/ was BTRFS before), but I am not sure about this.)
Planeshift goes from 2 GB to about 4 GB RSS and then the machine usually
starts to swap to SSD.

I did not get around to report this yet. The machine is basically locked (at
least for long periods of times like minutes). I intend to collect some
photos and upload them somewhere, cause I do not see anything in logs after

I think this happens *before* real OOM conditions are met (i.e. all of swap
is being used up as well).

In backtraces btrfs related stuff appears.

Expected results of cause: System continues swapping and if OOM conditions
are met calls the OOM killer (which might try to get rid of running
Planeshift client).

Current workaround: Develop a good feeling on when to better restart the PS
client. :)

So for now just a heads up that I have seen similar issues. (But I think my
backtraces might have been different, difficult to say since some of it
scrolls by quite quickly.)

Martin 'Helios' Steigerwald -
GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7
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