Re: WARN_ON_ONCE() hit at kernel/events/core.c:330

From: Thomas-Mich Richter
Date: Wed Apr 10 2019 - 09:51:40 EST

On 4/9/19 10:53 AM, Mark Rutland wrote:
> On Mon, Apr 08, 2019 at 11:50:31AM +0200, Peter Zijlstra wrote:
>> On Mon, Apr 08, 2019 at 10:22:29AM +0200, Peter Zijlstra wrote:
>>> On Mon, Apr 08, 2019 at 09:12:28AM +0200, Thomas-Mich Richter wrote:


>> Instead encode the CPU number in @pending_disable, such that we can
>> tell which CPU requested the disable. This then allows us to detect
>> the above scenario and even redirect the IPI to make up for the failed
>> queue.
>> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
>> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
>> Cc: Hendrik Brueckner <brueckner@xxxxxxxxxxxxx>
>> Cc: acme@xxxxxxxxxx
>> Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
>> Cc: Mark Rutland <mark.rutland@xxxxxxx>
>> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
>> Reported-by: Thomas-Mich Richter <tmricht@xxxxxxxxxxxxx>
>> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> I can't think of a nicer way of handling this, so FWIW:
> Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
> Mark.
>> ---

Thanks for the fix with commit id 86071b11317550d994b55ce5e31aa06bcad783b5.

However doing an fgrep on the pending_disable member of struct perf_event
reveals two more hits in file kernel/events/ringbuffer.c when events
have auxiliary data.

Not sure if this needs to be addresses too, just wanted to let you know.

Thomas Richter, Dept 3252, IBM s390 Linux Development, Boeblingen, Germany
Vorsitzender des Aufsichtsrats: Matthias Hartmann
GeschÃftsfÃhrung: Dirk Wittkopp
Sitz der Gesellschaft: BÃblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294