linux-kernel - Re: Bug: Fatal errors result in infinite stream of error messages

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Date:	Wed, 3 Dec 2014 21:52:37 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	rui wang <ruiv.wang@...il.com>
Cc:	linux-kernel@...r.kernel.org, tony.luck@...el.com, aris@...hat.com,
	rui.y.wang@...el.com
Subject: Re: Bug: Fatal errors result in infinite stream of error messages

On Wed, Dec 03, 2014 at 05:11:49PM +0800, rui wang wrote:
> The problem is because kdump fails to load a new kernel, and we're
> executing past crash_kexec() in panic(). And it calls
> bust_spinlocks(0) which calls into the GPU driver trying to unblank
> the screen, which eventually calls __schedule() while waiting for a
> mutex to be released. But we're still in the machine check context.
> The infinite stream of errors is because there's a for(;;) loop in
> __mutex_lock_common(), so we enter __schedule() again and again.

Hmm, there's a bust_spinlocks(1) call in mce_panic() for which I have no
idea what it is for? To stop us from scheduling?

If so, why doesn't it stop us...?

There's also this:

void console_unblank(void)
{
        struct console *c;

        /*
         * console_unblank can no longer be called in interrupt context unless
====>    * oops_in_progress is set to 1..
         */
        if (oops_in_progress) {
                if (down_trylock_console_sem() != 0)
                        return;
        } else
                console_lock();


-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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