Re: [PATCH] powerpc/perf: Account for interrupts during PMC overflow for an invalid SIAR check

On Thu, 6 Aug 2020 08:46:32 -0400, Athira Rajeev wrote:

Performance monitor interrupt handler checks if any counter has overflown
and calls `record_and_restart` in core-book3s which invokes
`perf_event_overflow` to record the sample information.
Apart from creating sample, perf_event_overflow also does the interrupt
and period checks via perf_event_account_interrupt.

Currently we record information only if the SIAR valid bit is set
( using `siar_valid` check ) and hence the interrupt check.
But it is possible that we do sampling for some events that are not
generating valid SIAR and hence there is no chance to disable the event
if interrupts is more than max_samples_per_tick. This leads to soft lockup.

[...]

Applied to powerpc/fixes.

[1/1] powerpc/perf: Fix soft lockups due to missed interrupt accounting
      https://git.kernel.org/powerpc/c/17899eaf88d689529b866371344c8f269ba79b5f

cheers