linux-kernel - [3.8-rc3 -> 3.8-rc4 regression] Re: [PATCH] module, async: async_synchronize

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Date:	Mon, 12 Aug 2013 00:04:11 -0700
From:	Jonathan Nieder <jrnieder@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ming Lei <ming.lei@...onical.com>,
	Alex Riesen <raa.lkml@...il.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Jens Axboe <axboe@...nel.dk>,
	USB list <linux-usb@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: [3.8-rc3 -> 3.8-rc4 regression] Re: [PATCH] module, async:
 async_synchronize_full() on module init iff async is used

Hi,

Tejun Heo wrote:

> This avoids the described deadlock because iosched module doesn't use
> async and thus wouldn't invoke async_synchronize_full().  This is
> hacky and incomplete.  It will deadlock if async module loading nests;
> however, this works around the known problem case and seems to be the
> best of bad options.
>
> For more details, please refer to the following thread.
>
>   http://thread.gmane.org/gmane.linux.kernel/1420814

My laptop fails to boot[1] with the message 'Volume group "data" not
found'.  Bisects to v3.8-rc4~17 (the above commit).  Reverting that
commit on top of current "master" (d92581fcad18, 2013-08-10) produces
a working kernel.  dmesg output from that working kernel attached.
More details, including .config, at [2].

Any ideas for tracking this down?

Thanks,
Jonathan

[1] Screenshot: http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=5;filename=bad_3.10.3-1.jpg;att=1;bug=719464
Screenshot in recovery mode: http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=5;filename=bad_3.10.3-1_recovery.jpg;att=2;bug=719464
[2] http://bugs.debian.org/719464

View attachment "dmesg" of type "text/plain" (46505 bytes)