linux-kernel - Re: bcache: Fix a writeback performance regression

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

Date:	Wed, 21 Aug 2013 16:47:15 -0700
From:	Kent Overstreet <kmo@...erainc.com>
To:	Stefan Priebe - Profihost AG <s.priebe@...fihost.ag>
Cc:	Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org,
	linux-bcache@...r.kernel.org
Subject: Re: bcache: Fix a writeback performance regression

On Tue, Aug 20, 2013 at 10:07:45AM +0200, Stefan Priebe - Profihost AG wrote:
> Am 20.08.2013 10:01, schrieb Stefan Priebe - Profihost AG:
> > Am 20.08.2013 00:27, schrieb Kent Overstreet:
> >> On Mon, Aug 19, 2013 at 12:09:24AM +0200, Stefan Priebe wrote:
> >>>
> >>> Vanilla 3.10.7 + bcache: Fix a writeback performance regression
> >>>
> >>> http://pastebin.com/raw.php?i=LXZk4cMH
> >>
> >> Whoops, at first I thought this was the same bug as one I'd already been
> >> chasing down that had been a harmless bug - turns out I didn't look
> >> closely enough at the backtrace.
> >>
> >> What happened is background writeback is deadlocking, because for some
> >> reason the workqueue it's running out of is a singlethreaded workqueue,
> >> so as soon as it decides to queue enough writeback bios that it has to
> >> sleep on that semaphore (which often won't happen due to the PD
> >> controller based ratelimiting) - boom, deadlock.
> >>
> >> Here's the fixup patch I just tested and am applying:
> 
> Oh i'm now seeing very high CPU spikes of kworker... i don't see if i
> remove bcache: Fix a writeback performance regression.

Are you able to reproduce it? I'm not having any luck reproducing it...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/