Le 2015-10-22 10:53, Filipe Manana a écrit :
On Thu, Oct 22, 2015 at 6:32 AM, Erkki Seppala <[email protected]>
wrote:
Hello,
Recently I added daily rebalancing to my cron.d (after finding myself
in
the no-space-situation), and not long after that, I found my PC had
crashed over night. Having no sign in the logs anywhere (not even over
network even though there should be) I had nothing to go on, but this
night it crashed again after starting the rebalance, and this time
there
was some information on the kernel log.
Kernel version: 4.2.3 (package linux-image-4.2.0-1-amd64 version
4.2.3-1
from Debian Unstable)
The dump is available at:
http://www.modeemi.fi/~flux/btrfs/btrfs-BUG-2015-10-55.txt
The log is available as well (stripped some unrelated USB- and
firewall
logging, showing that last evening there was some kernel task hung for
120 seconds; but it's in another btrfs filesystem and is another
story):
http://www.modeemi.fi/~flux/btrfs/btrfs-2015-10-55.txt
I'm not quite sure which of the btrfs balance commands caused the
issue. But there is my script:
#!/bin/sh
fs="$1"
if [ -z "$fs" ]; then
echo usage: btrfs-balance / 0 1 5 10 20 50
exit 1
fi
fs="$1"
shift
for usage in d m; do for a in "$@"; do date; /bin/btrfs balance start
"$fs" -v -${usage}usage=$a; done; done
And it was started at 07:30 with:
/usr/local/sbin/btrfs-balance / 0 1 2 5 10 20 30 50 70
I should add that the filesystem in question is backed by MD RAID10
and
that is backed by four SSDs, so it's reasonably fast in IO, if that
affects anything. There should have been no much competing IO at the
time of the occurrence.
Before Duncan asks ;-), I only have a moderate number of subvolumes
and
snapshots, ie. one subvolume for each of /, /var/log/journal and
/home,
24 snapshots of / and /home plus <10 snapshots of /.
Before that balance there was another balance on a another BTRFS
RAID10,
but given the time stamp I think I can easily say it wasn't the cause.
I don't really have other 'solutions' than disabling the rebalancing
for
the time being, and only use it as-needed as I had earlier done..
Try this (just sent a few minutes ago):
https://patchwork.kernel.org/patch/7463161/
Awesome, I'll also try it right now under 4.3.0-rc6. My system is
currently hit so hard by this bug that it no longer survives a balance
for longer than a few minutes.
Will keep you posted on the outcome.
Thanks,
--
Stéphane.
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