Re: [PATCH wq/for-4.0-fixes v2] workqueue: fix hang involving racing cancel[_delayed]_work_sync()'s for PREEMPT_NONE

From: Tejun Heo
Date: Thu Mar 05 2015 - 04:36:48 EST


On Thu, Mar 05, 2015 at 10:24:50AM +0100, Tomeu Vizoso wrote:
...
> [ 317.251001] PC is at bit_waitqueue+0x38/0x6c
...
> [ 317.420658] [<c028fe18>] (bit_waitqueue) from [<c0270d34>]
> (__cancel_work_timer+0x28/0x1b0)
> [ 317.430598] [<c0270d34>] (__cancel_work_timer) from [<c0270ed8>]
> (cancel_work_sync+0x1c/0x20)
> [ 317.440672] [<c0270ed8>] (cancel_work_sync) from [<bf0ed138>]
> (regulatory_exit+0x24/0x17c [cfg80211])
> [ 317.451396] [<bf0ed138>] (regulatory_exit [cfg80211]) from
> [<bf125184>] (cfg80211_exit+0x38/0x4c [cfg80211])
> [ 317.462726] [<bf125184>] (cfg80211_exit [cfg80211]) from
> [<c02c8b4c>] (SyS_delete_module+0x1b4/0x1f8)
> [ 317.473411] [<c02c8b4c>] (SyS_delete_module) from [<c0210a00>]
> (ret_fast_syscall+0x0/0x34)

Ah, I think that's from feeding static address to virt_to_page. :(
Reverted the patch from the branch. Will think more about what to do.

Thanks.

--
tejun
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