linux-kernel - Re: [Linux v4.2] workqueue: llvmlinux: acpid: BUG: sleeping function called from invalid context at kernel/workqueue.c:2680

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Date:	Mon, 14 Sep 2015 13:41:20 +0200
From:	Sedat Dilek <sedat.dilek@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Lai Jiangshan <jiangshanlai@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Linux v4.2] workqueue: llvmlinux: acpid: BUG: sleeping function
 called from invalid context at kernel/workqueue.c:2680

On Fri, Sep 11, 2015 at 6:12 PM, Sedat Dilek <sedat.dilek@...il.com> wrote:
> On Thu, Sep 10, 2015 at 4:53 PM, Tejun Heo <tj@...nel.org> wrote:
>> On Thu, Sep 10, 2015 at 10:52:27AM -0400, Tejun Heo wrote:
>>> Hey,
>>>
>>> On Thu, Sep 10, 2015 at 09:04:27AM +0800, Lai Jiangshan wrote:
>>> > I think we need to add might_sleep() on the top of __cancel_work_timer().
>>> > The might_sleep() on the start_flush_work() doesn't cover all the
>>> > paths of __cancel_work_timer().
>>> > And it can help to narrow the area of this bug.
>>>
>>> Sure, can you submit a patch?
>>
>> That said, this one is likely not a bug in the kernel code but more
>> likely llvm either miscompiling or deviating from gcc behavior on some
>> corner cases.
>>
>
> An llvmlinux-patched Linux v4.2 kernel compiled with GCC v4.9 does not
> show this BUG line.
>

This bug seems to be more serious as I thought.

On my llvmlinux-patched Linux v4.2 my Xorg crashes reproducibly when
marking a text in Firefox with my Logitech mouse.
My LightDM login-manager restarts and I have to re-login.

With a GCC v4.9 compiled Linux v4.2 this does not happen - the
bug-line does not occur.

My mouse (USB 2.0) is attached to a USB 3.0 plug on my notebook.
If this matters...

- Sedat -
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