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From: Jeff Moyer <jmoyer@redhat.com>
To: "Jörn Engel" <joern@logfs.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] add blockconsole
Date: Wed, 25 Apr 2012 11:52:28 -0400	[thread overview]
Message-ID: <x49vcknkdvn.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <20120425132513.GA23492@logfs.org> (=?utf-8?Q?=22J=C3=B6rn?= Engel"'s message of "Wed, 25 Apr 2012 09:25:14 -0400")

Jörn Engel <joern@logfs.org> writes:

> On Wed, 25 April 2012 09:42:39 -0400, Jeff Moyer wrote:
>> 
>> Neat idea, but I'm curious to know how it works when the system panics
>> and you no longer can schedule the writeback thread.  What are the
>> limitations you've seen in practice?
>
> If the writeback thread doesn't get scheduled, you lose that
> information.  Formerly I did the submit_bio directly, but lockdep
> reminded me that I shouldn't do so from interrupt context.  Bummer.

Well, submit_bio can sleep, obviously.  Perhaps you could explore
registering a panic notifier, and then flush the logs from there?
Unfortunately, there is always the possibility that some required locks
will be taken, but it might get you a little bit further.  Or, you could
explore the route that the diskdump or lkcd folks took, implementing
their own polling mode drivers.

Cheers,
Jeff

  reply	other threads:[~2012-04-25 16:26 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-24 20:59 [RFC][PATCH] add blockconsole Jörn Engel
2012-04-25 13:42 ` Jeff Moyer
2012-04-25 13:25   ` Jörn Engel
2012-04-25 15:52     ` Jeff Moyer [this message]
2012-07-12 17:46       ` [PATCH] add blockconsole version 1.1 Jörn Engel
2012-07-13 13:03         ` Borislav Petkov
2012-07-13 16:20           ` Jörn Engel
2012-07-13 21:14             ` Borislav Petkov
2012-07-16 12:46             ` Borislav Petkov
2012-07-18 18:53               ` Jörn Engel
2012-07-18 21:45                 ` Borislav Petkov
2012-07-18 21:08                   ` Jörn Engel
2012-07-19  9:26                     ` Borislav Petkov
2012-07-23 20:04                   ` Jörn Engel
2012-07-24 15:42                     ` Borislav Petkov
2012-07-24 14:53                       ` Jörn Engel
2012-07-24 16:25                         ` Borislav Petkov
2012-07-24 17:52                           ` Jörn Engel
2012-07-24 20:28                             ` Borislav Petkov
2012-12-19 10:20                               ` Borislav Petkov
2012-08-14 11:54                 ` Jan Engelhardt
2012-07-23 14:33         ` Tvrtko Ursulin
2012-07-23 20:02           ` Jörn Engel
2012-07-24  8:01             ` Tvrtko Ursulin
2012-07-24 14:38               ` Jörn Engel
2012-07-25  8:17                 ` Tvrtko Ursulin
2012-07-25 16:39                   ` Jörn Engel

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