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Date:   Fri, 2 Oct 2020 19:47:12 +0300
From:   Ville =?iso-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
To:     Rong Chen <rong.a.chen@intel.com>
Cc:     kernel test robot <lkp@intel.com>, Lyude Paul <lyude@redhat.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        LKML <linux-kernel@vger.kernel.org>, lkp@lists.01.org
Subject: Re: [LKP] Re: [drm/dp] 6509ca051a: PANIC:double_fault
Message-ID: <20201002164712.GD6112@intel.com>
References: <20200924143049.GJ28663@shao2-debian>
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On Tue, Sep 29, 2020 at 01:26:09PM +0800, Rong Chen wrote:
> 
> 
> On 9/25/20 12:42 AM, Ville Syrjälä wrote:
> > On Thu, Sep 24, 2020 at 10:30:49PM +0800, kernel test robot wrote:
> >> Greeting,
> >>
> >> FYI, we noticed the following commit (built with gcc-9):
> >>
> >> commit: 6509ca051abf4ff60d63732badcb2173a715f741 ("drm/dp: Add drm_dp_downstream_{min,max}_tmds_clock()")
> > That doesn't really do anything on its own. So can't see how it would
> > make anything blow up.
> 
> Hi Ville,
> 
> The issue is 100% reproducible, could you try the reproduce steps:
> 
> To reproduce:
> 
>          # build kernel
> 	cd linux
> 	cp config-5.9.0-rc4-00881-g6509ca051abf4 .config
> 	make HOSTCC=gcc-9 CC=gcc-9 ARCH=i386 olddefconfig prepare modules_prepare bzImage
> 
>          git clone https://github.com/intel/lkp-tests.git
>          cd lkp-tests
>          bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email

Managed to find some Ubuntu machine where that would run.

$ time ./bin/lkp qemu -k ~/bzImage ~/job-script
...
[    0.000000] Linux version 5.9.0-rc4-00027-g6509ca051abf (...) (gcc (Gentoo 9.3.0-r1 p3) 9.3.0, GNU ld (Gentoo 2.33.1 p2) 2.33.1) #2 SMP PREEMPT Fri Oct 2 19:24:28 EEST 2020
...
[   12.717392] Applicom driver: $Id: ac.c,v 1.30 2000/03/22 16:03:57 dwmw2 Exp $
[   12.718889] ac.o: No PCI boards found.
[   12.719696] ac.o: For an ISA board you must supply memory and irq parameters.
[   12.721269] toshiba: not a supported Toshiba laptop
[   12.722779] random: get_random_u32 called from arch_rnd+0x1c/0x40 with crng_init=0
[   12.722784] random: get_random_u32 called from randomize_stack_top+0x35/0x50 with crng_init=0
[   12.722787] random: get_random_u32 called from arch_align_stack+0x35/0x50 with crng_init=0
...
real	11m35,352s
user	13m40,549s
sys	0m13,071s
$ echo $?
0

-- 
Ville Syrjälä
Intel