Re: [patch] Real-Time Preemption, -RT-2.6.10-rc1-mm3-V0.7.18

From: Ingo Molnar
Date: Mon Nov 08 2004 - 03:46:29 EST



* Eran Mann <emann@xxxxxxx> wrote:

> Ingo Molnar wrote:
> >i have released the -V0.7.18 Real-Time Preemption patch, which can be
> >downloaded from:
> >
> > http://redhat.com/~mingo/realtime-preempt/
>
> I got the attached oops on 2.6.10-rc1-mm3-RT-V0.7.18 (probably during the
> daily cron job). Later in the morning when I tried to access some
> filesystems
> I got the attached deadlock report.

> Nov 8 04:19:32 eran kernel: BUG at include/linux/spinlock.h:767!
> Nov 8 04:19:32 eran kernel: ------------[ cut here ]------------
> Nov 8 04:19:32 eran kernel: kernel BUG at include/linux/spinlock.h:767!

ok, your bugreport pinpointed the bug: an RT-patch merging mistake when
i merged -RT to the spinlock-checker changes in recent BK.

the fix is below, but i've also put it into -V0.7.20 (which i released a
couple of minutes ago). Does this patch (or -V0.7.20) fix the kjournald
crash for you?

Ingo

--- linux/include/linux/spinlock.h.orig
+++ linux/include/linux/spinlock.h
@@ -750,7 +750,7 @@ static inline void bit_spin_lock(int bit
*/
static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
{
-#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT)
if (test_and_set_bit(bitnum, addr))
return 0;
#endif
-
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