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From:   Subhashini Rao Beerisetty <subhashbeerisetty@gmail.com>
Date:   Sat, 16 May 2020 21:45:15 +0530
Message-ID: <CAPY=qRRJ6aZbbRnWfvjqojs08Z7H-+-6nzLAcpzjDcQOJ40fOQ@mail.gmail.com>
Subject: Re: general protection fault vs Oops
To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     =?UTF-8?Q?Valdis_Kl=C4=93tnieks?= <valdis.kletnieks@vt.edu>,
        kernelnewbies <kernelnewbies@kernelnewbies.org>,
        linux-kernel@vger.kernel.org
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On Sat, May 16, 2020 at 9:29 PM Randy Dunlap <rdunlap@infradead.org> wrote:
>
> On 5/16/20 6:53 AM, Valdis Kl=C4=93tnieks wrote:
> > On Sat, 16 May 2020 18:05:07 +0530, Subhashini Rao Beerisetty said:
> >
> >> In the first attempt when I run that test case I landed into =C3=A2=E2=
=82=AC=C5=93general
> >> protection fault: 0000 [#1] SMP" .. Next I rebooted and ran the same
> >> test , but now it resulted the =C3=A2=E2=82=AC=C5=93Oops: 0002 [#1] SM=
P".
> >
> > And the 0002 is telling you that there's been 2 previous bug/oops since=
 the
> > reboot, so you need to go back through your dmesg and find the *first* =
one.
> >
> >> In both cases the call trace looks exactly same and RIP points to
> >> =C3=A2=E2=82=AC=C5=93native_queued_spin_lock_slowpath+0xfe/0x170"..
> >
> > The first few entries in the call trace are the oops handler itself. So=
...
> >
> >
> >> May 16 12:06:17 test-pc kernel: [96934.567347] Call Trace:
> >> May 16 12:06:17 test-pc kernel: [96934.569475]  [<ffffffff8183c427>]__=
raw_spin_lock_irqsave+0x37/0x40
> >> May 16 12:06:17 test-pc kernel: [96934.571686]  [<ffffffffc0606812>] e=
vent_raise+0x22/0x60 [osa]
> >> May 16 12:06:17 test-pc kernel: [96934.573935]  [<ffffffffc06aa2a4>] m=
ulti_q_completed_one_buffer+0x34/0x40 [mcore]
> >
> > The above line is the one where you hit the wall.
> >
> >> May 16 12:59:22 test-pc kernel: [ 3011.405602] Call Trace:
> >> May 16 12:59:22 test-pc kernel: [ 3011.407892]  [<ffffffff8183c427>] _=
raw_spin_lock_irqsave+0x37/0x40
> >> May 16 12:59:22 test-pc kernel: [ 3011.410256]  [<ffffffffc0604812>] e=
vent_raise+0x22/0x60 [osa]
> >> May 16 12:59:22 test-pc kernel: [ 3011.412652]  [<ffffffffc06b72a4>] m=
ulti_q_completed_one_buffer+0x34/0x40 [mcore]
> >
> > And again.
> >
> > However,  given that it's a 4.4 kernel from 4 years ago, it's going to =
be
> > hard to find anybody who really cares.
>
> Right.
>
> > In fact. I'm wondering if this is from some out-of-tree or vendor patch=
,
> > because I'm not finding any sign of that function in either the 5.7 or =
4.4
> > tree.  Not even a sign of ## catenation abuse - no relevant hits for
> > "completed_one_buffer" or "multi_q" either
>
> Modules linked in:
> dbg(OE) mcore(OE) osa(OE)
>
> Out-of-tree, unsigned modules loaded.
Yes, those are out-of-tree modules. Basically, my question is, in
general what is the difference between 'general protection fault' and
'Oops' failure in kernel mode.

> We don't know what those are or how to debug them.
>
> > I don't think anybody's going to be able to help unless somebody first
> > identifies where that function is....
> >
>
>
> --
> ~Randy
>