Messages in this thread |  | | Date | Sat, 25 Jul 2020 12:38:50 +0200 | From | Ingo Molnar <> | Subject | Re: 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
|  |