Messages in this thread | | | Date | Tue, 14 Feb 2023 10:49:07 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3] x86/kdump: Handle blocked NMIs interrupt to avoid kdump crashes |
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On Tue, Feb 14, 2023 at 05:30:46PM +0800, Zeng Heng wrote:
> > I never remember the shutdown paths -- do we force wipe the PMU > > registers somewhere before this? > > I have checked the panic process, and there is no wipe operation for PMU > registers, > > which causes the watchdog bites. > > Do you mean we should directly disable PMU registers instead of calling > `iret_to_self` to > > consume blocked NMI interrupts ?
If you don't wipe the PMU, there will be many and continuous NMIs, a single IRET-to-SELF isn't going to safe you.
Anyway, I had a bit of a grep around and I find we have:
kernel/events/core.c: register_reboot_notifier(&perf_reboot_notifier);
which should end up killing all the PMU activity. Somewhere around there there's also a CONFIG_KEXEC_CORE ifdef, so I'm thinking it gets called on the panic->crash-kernel path too?
If not, someone should look at doing something there.
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