linux-kernel - Re: Please add to stable: module: don't unlink the module until we've removed all exposure.

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Date:	Mon, 03 Jun 2013 08:59:38 -0700
From:	Ben Greear <greearb@...delatech.com>
To:	Joe Lawrence <joe.lawrence@...atus.com>
CC:	Rusty Russell <rusty@...tcorp.com.au>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	stable@...r.kernel.org
Subject: Re: Please add to stable:  module: don't unlink the module until
 we've removed all exposure.

On 06/03/2013 07:17 AM, Joe Lawrence wrote:

>>> Hi Rusty,
>>>
>>> I had pointed Ben (offlist) to that bugzilla entry without realizing
>>> there were other earlier related fixes in this space.  Re-viewing bz-
>>> 58011, it looks like it was opened against 3.8.12, while Ben and myself
>>> had encountered module loading problems in versions 3.9 and
>>> 3.9.[1-3].  I can update the bugzilla entry to add a comment noting commit
>>> a49b7e82 "kobject: fix kset_find_obj() race with concurrent last
>>> kobject_put()".
>>>
>>> That said, it doesn't appear that commit 944a1fa "module: don't unlink the
>>> module until we've removed all exposure" has not made it into any stable
>>> kernel.  On my system, applying this on top of 3.9 resolved a module
>>> unload/load race that would occasionally occur on boot (two video adapters
>>> of the same make, the module unloads for whatever reason and I see "module
>>> is already loaded" and "sysfs: cannot create duplicate filename
>>> '/module/mgag200'" messages every 5-10% instances.)  I have logs if you
>>> were interested in these warnings/crashes.

It at least works around the problem for me as well.  But, a more rare
migration/[0-3] (I think) related lockup still exists in 3.9.4 for me,
so I will also try applying that other kobject patch and continue testing
today...

Thanks,
Ben


-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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