lkml.org 
[lkml]   [2020]   [Jul]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Regression on todays tip/master (commit 16f70beccf43)

* Ingo Molnar <mingo@kernel.org> wrote:

>
> * Joerg Roedel <joro@8bytes.org> wrote:
>
> > On Thu, Jul 23, 2020 at 04:46:04PM +0200, Thomas Gleixner wrote:
> > > Joerg Roedel <joro@8bytes.org> writes:
> > > > while testing the SEV-ES patches on todays tip/master I triggered the BUG
> > > > below:
> > > >
> > > > [ 137.629660] ------------[ cut here ]------------
> > > > [ 137.630769] kernel BUG at kernel/signal.c:1917!
> > > > [ 137.631796] invalid opcode: 0000 [#1] SMP NOPTI
> > > > [ 137.632822] CPU: 3 PID: 28596 Comm: test_syscall_vd Not tainted 5.8.0-rc6-tip+ #3
> > > > [ 137.634495] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
> > > > [ 137.636236] RIP: 0010:do_notify_parent+0x25c/0x290
> > > > The guest had 4 VCPUs and ran 4 instances of the in-kernel x86-selftests
> > > > in a loop, together with 'perf top -e cycles:k'. As you can see in the
> > > > time-stamps, the issue triggered pretty quickly.
> > > >
> > > > Please let me know if you need more information or testing from my side.
> > >
> > > Any chance to bisect this?
> >
> > Yes, will try. I am currently testing plain -rc6, it seems to be fine.
> > Bisecting is next.
>
> Given that you are perf stress-testing the box, some recent perf
> commit would be the primary suspect - before doing a full bisect you
> might want to try current perf/core (2ac5413e5edc) and its upstream
> base: v5.8-rc3, to narrow it down.
>
> But in principle any other commit could be the cause as well, the
> assert suggests memory corruption - I don't think we changed anything
> in the signal code.

On a second thought, I think this recent bug might have been the
culprit:

d136122f5845: ("sched: Fix race against ptrace_freeze_trace()")

Fixed in tip:sched/urgent - this is why it went away in your testing
perhaps?

I'm sending this fix to Linus today.

Thanks,

Ingo

\
 
 \ /
  Last update: 2020-07-25 12:39    [W:0.070 / U:0.180 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site