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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Rik van Riel <riel@surriel.com>, linux-kernel@vger.kernel.org
Cc:     Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>, kernel-team@fb.com,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org
Subject: Re: [PATCH] x86,mm: print likely CPU at segfault time
In-Reply-To: <20210719150041.3c719c94@imladris.surriel.com>
References: <20210719150041.3c719c94@imladris.surriel.com>
Date:   Wed, 21 Jul 2021 22:36:07 +0200
Message-ID: <87sg07pfpk.ffs@nanos.tec.linutronix.de>
MIME-Version: 1.0
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Rik,

On Mon, Jul 19 2021 at 15:00, Rik van Riel wrote:
>
> Adding a printk to show_signal_msg() achieves that purpose. It isn't
> perfect since the task might get rescheduled on another CPU between
> when the fault hit and when the message is printed, but it should be
> good enough to show correlation between userspace and kernel errors
> when dealing with a bad CPU.

we could collect the cpu number in do_*_addr_fault() before interrupts
are enabled and just hand it through. There are only a few callchains
which end up in __bad_area_nosemaphore().

Thanks,

        tglx