linux-kernel - Re: [PATCH RFC 2/2] genirq/matrix: WARN_ON_ONCE() when cm->allocated/m->total

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Date:   Thu, 18 Mar 2021 20:29:44 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, x86@...nel.org
Cc:     Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 2/2] genirq/matrix: WARN_ON_ONCE() when cm->allocated/m->total_allocated go negative

On Thu, Mar 18 2021 at 08:58, Vitaly Kuznetsov wrote:
> Thomas Gleixner <tglx@...utronix.de> writes:
>> There is a way more useful way to handle this. In such a case the bit is
>> NOT set in the alloc map. So:
>>
>>     if (!WARN_ON_ONCE(test_and_clear_bit(bit, cm->alloc_map)))
>>     	   return;
>>
>> would have caught the problem at hand nicely and let the machine survive
>> while just throwing warns and continuing is broken to begin with.
>
> Thanks, I like the idea. I didn't do that probably because the problem
> which triggered me to write these patches wasn't fatal, it was just
> causing CPU0 offlining to fail.

Can you whip up a patch for that?

Thanks,

        tglx