linux-kernel - IO hang with kernel above 4.4.21, heavy IO, btrfs, xen

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <CAHpsFVedoBmbm6SmLL7y9hhzPToSdraPiayMGc8cM9Vpt5HzHg@mail.gmail.com>
Date:   Wed, 22 Mar 2017 13:42:35 -0600
From:   Cheyenne Wills <cheyenne.wills@...il.com>
To:     linux-kernel@...r.kernel.org
Subject: IO hang with kernel above 4.4.21, heavy IO, btrfs, xen

I have a reproducible system hang that appears to be the result of heavy IO.

I originally posted the problem to the linux-block mailing list back
in January, but haven't heard back.

Not sure if I reported to the correct area.

There is a bugzill.kernel.org issue open that contains the details of
the problem  https://bugzilla.kernel.org/show_bug.cgi?id=193331

The problem occurs if there is a heavy IO load (the system in question
is a FTP server that locked up during a heavy load).  I am able to
reproduce the problem using a btrfs scrub to the file system (the
filesystem spans multiple devices).  I have a "test system" where I
can reproduce the problem at will (it takes only a few minutes to
cause the IO to hang up).

With a 4.0.5 kernel, I'm unable to reproduce the hang (and the system
in question runs just fine).  A kernel above 4.4.21 (maybe earlier?)
results in the hang described in the above bugzilla ticket.

I would appreciate any suggestions on performing further further
diagnostics, or if there is additional information needed to dig
deeper into the problem.

I'm not subscribed to the lkml, so a cc to cheyenne.wills@...il.com
would be appreciated.

Thanks in advance.

Cheyenne Wills
cheyenne.wills@...il.com