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

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Message-Id: <a24a2dca-72f3-ff56-5004-97c6ce86f6af@linux.ibm.com>
Date:   Wed, 10 Apr 2019 15:51:24 +0200
From:   Thomas-Mich Richter <tmricht@...ux.ibm.com>
To:     Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Kees Cook <keescook@...omium.org>, acme@...hat.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Hendrik Brueckner <brueckner@...ux.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>, jolsa@...hat.com
Subject: Re: WARN_ON_ONCE() hit at kernel/events/core.c:330

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@...ibm.com>
>> Cc: Kees Cook <keescook@...omium.org>
>> Cc: Hendrik Brueckner <brueckner@...ux.ibm.com>
>> Cc: acme@...hat.com
>> Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Cc: Jiri Olsa <jolsa@...hat.com>
>> Reported-by: Thomas-Mich Richter <tmricht@...ux.ibm.com>
>> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> 
> I can't think of a nicer way of handling this, so FWIW:
> 
> Acked-by: Mark Rutland <mark.rutland@....com>
> 
> 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
--
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