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

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Date:	Tue, 26 Nov 2013 15:29:30 -0600
From:	Josh Hunt <joshhunt00@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Jonathan Nieder <jrnieder@...il.com>,
	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: Re: [3.8-rc3 -> 3.8-rc4 regression] Re: [PATCH] module, async:
 async_synchronize_full() on module init iff async is used

On Mon, Aug 12, 2013 at 10:09 AM, Tejun Heo <tj@...nel.org> wrote:
> Hello, Jonathan.
>
> On Mon, Aug 12, 2013 at 12:04:11AM -0700, Jonathan Nieder wrote:
>> 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?
>
> Which initrd / boot script are you using?  It looks like lvm assemble
> scripts are running before sdX are detected leading to volume assembly
> failure.  Before the patch, any module loading would end up
> synchronizing async probes but after the patch modprobe invocations
> which don't schedule them won't be.  Does your boot script happen to
> run multiple modprobes in parallel and proceed to configure lvm
> without waiting for modprobes of libata drivers to finish?
>
> Thanks.
>
> --
> tejun
> --
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I'm also hitting a regression b/c of this patch. Booting 3.10.20 on a
number of older machines with onboard sata controllers are unable to
find their root device quickly enough. I bisected the issue down to
774a1221e862b343388347bac9b318767336b20b. Reverting it allows my
systems to boot fine. I'm seeing this with both sata_svw and ahci. I'm
using ubuntu precise userspace which is using initramfs-tools
0.99ubuntu13.1. From what I can tell the modprobes in this initrd are
done in serial, but the port probing is async. This allows init to
continue on to try and mount root, but it's not there yet.

I'm attaching some serial log output with initcall_debug enabled.

Both ahci and sata_svw call ata_host_activate(), which call
ata_host_register() and async_schedule(async_port_probe, ap).

Let me know what other information you may need.
Thanks

-- 
Josh

Download attachment "seriallog" of type "application/octet-stream" (5990 bytes)