linux-kernel - Re: [ghes_copy_tofrom_phys] BUG: sleeping function called from invalid context at mm/page

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Date:   Mon, 30 Oct 2017 10:17:27 -0400
From:   Tyler Baicar <tbaicar@...eaurora.org>
To:     Borislav Petkov <bp@...e.de>
Cc:     Fengguang Wu <fengguang.wu@...el.com>,
        Huang Ying <ying.huang@...el.com>,
        Chen Gong <gong.chen@...ux.intel.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Will Deacon <will.deacon@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [ghes_copy_tofrom_phys] BUG: sleeping function called from
 invalid context at mm/page_alloc.c:4150

On 10/30/2017 10:06 AM, Borislav Petkov wrote:
> On Mon, Oct 30, 2017 at 10:01:52AM -0400, Tyler Baicar wrote:
>> This is not as important for polling sources as it is for the
>> interrupt sources since polling sources are regularly checked and
>> shouldn't be used for fatal error scenarios. For interrupt driven
>> sources, there could already be a fatal error pending, so we should
>> handle it immediately.
> Whatever it is, you can't call it there as it could deadlock. You need
> to think about doing that differently. If you can't come up with a
> solution quickly, it should be reverted and then you can try again
> later.
I'm okay with reverting this and coming up with another solution, but that seems 
like it
could be masking a problem. It should be valid for the polling timer to expire 
right after
this probe function completes which would then trigger ghes_poll_func() to be called
and that calls into ghes_proc() immediately.

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