From: Roman Mamedov <rm@romanrm.net>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-btrfs@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: Kernel 4.4.0 KVM guest on Btrfs locks up on snapshotting
Date: Wed, 20 Jan 2016 18:58:10 +0500 [thread overview]
Message-ID: <20160120185810.2c566f98@natsu> (raw)
In-Reply-To: <1185704624.11958670.1453278484410.JavaMail.zimbra@redhat.com>
[-- Attachment #1: Type: text/plain, Size: 1239 bytes --]
On Wed, 20 Jan 2016 03:28:04 -0500 (EST)
Paolo Bonzini <pbonzini@redhat.com> wrote:
> Can you reproduce it on the host without QEMU in the middle?
I did not try to stress-test this on purpose yet, but this is an actively used
system which is snapshotting its /home, VMs and root subvolumes every hour, so
far no lock-ups of any other application than KVM, and with KVM it's trivially
easy to hit, in fact first two lockups occured in the first two hours of using
the kernel 4.4.0 at the hourly snapshots...
> Also, can you find the value of the "FUA" file in sysfs (e.g. with
> "cat /sys/block/sda/device/scsi_disk/*/FUA")?
It is 0 both in IDE and SCSI modes.
Since you mentioned queue depth, I tried setting this on SCSI:
echo 1 > /sys/block/sda/device/queue_depth
(was 128 by default). Does not solve the issue and doesn't seem to make it any
harder to hit.
Couple more details about the locked-up state:
- 0.0% "wa" state in 'top', so there's doesn't seem to be any disk activity
- I can disconnect and then successfully reconnect to the VNC port of the
locked-up QEMU/KVM process (!), so it looks like it's not entirely dead, but
just the virtualization part(?)
--
With respect,
Roman
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 181 bytes --]
next prev parent reply other threads:[~2016-01-20 13:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-19 22:02 Kernel 4.4.0 KVM guest on Btrfs locks up on snapshotting Roman Mamedov
2016-01-19 22:18 ` Paolo Bonzini
2016-01-19 23:03 ` Roman Mamedov
2016-01-20 8:28 ` Paolo Bonzini
2016-01-20 13:58 ` Roman Mamedov [this message]
2016-01-20 17:28 ` Paolo Bonzini
2016-01-20 18:46 ` Roman Mamedov
2016-01-20 20:38 ` Paolo Bonzini
2016-01-20 0:19 ` Liu Bo
2016-01-20 5:08 ` Roman Mamedov
2016-01-20 11:34 ` Paolo Bonzini
2016-01-20 15:08 ` Roman Mamedov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160120185810.2c566f98@natsu \
--to=rm@romanrm.net \
--cc=kvm@vger.kernel.org \
--cc=linux-btrfs@vger.kernel.org \
--cc=pbonzini@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).