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From: Andrew Morton <akpm@linux-foundation.org>
To: benh@kernel.crashing.org
Cc: mikey@neuling.org, kamalesh@linux.vnet.ibm.com,
	linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org,
	willy@debian.org
Subject: Re: [BUG] 2.6.25-rc3-mm1 kernel panic while bootup on powerpc ()
Date: Wed, 5 Mar 2008 16:44:38 -0800	[thread overview]
Message-ID: <20080305164438.fff7bb7c.akpm@linux-foundation.org> (raw)
In-Reply-To: <1204761811.21545.238.camel@pasglop>

On Thu, 06 Mar 2008 11:03:31 +1100
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

> 
> > Yes, we are - it's the semaphore rewrite which is doing this in
> > start_kernel().  It's being discussed.
> > 
> > Enabling interrupts too early on powerpc was discovered to be fatal on
> > powerpc years ago.  It looks like that remains the case.
> 
> Regarding these issues. I could make it non fatal and just WARN_ON,
> provided that I have a way to differentiate legal vs. illegal calls
> to local_irq_enable().

And local_irq_restore() and various other things.

> We already have that function mostly out of
> line in C code due to our lazy irq disabling scheme, so the overhead of
> testing some global kernel state would be minimum here.
> 
> However, I don't see anything around init/main.c:start_kernel() that I
> can use. What do you reckon here we should do ? Add some kind of global
> we set before calling local_irq_enable() ? Or make early_boot_irqs_on()
> do that generically 
> 
> It's currently defined as an empty inline without CONFIG_TRACE_IRQFLAGS
> but we could make it set a flag instead.
> 
> I'm pretty sure other archs have similar problems, especially in the
> embedded world where you are booted with random junk firmwares that may
> leave devices, interrupt controllers etc... in random state, and
> enabling incoming IRQs before the arch code properly initializes the
> main interrupt controller can be fatal. I know at least of an ARM board
> I worked on a while ago that had a similar issues.
> 
> On ppc32, unfortunately, our local_irq_enable/restore are nice inlines
> that whack the appropriate MSR bits directly, thus adding a test for a
> global flag would add some bloat/overhead that I'd like to avoid, at
> least until we decide to also do lazy disabling on those, if ever...

I'd have thought that the way to do this would be to add it to lockdep -
lockdep already has all the infrastructure and code sites to do this.

Set some special flag saying its-ok-to-enable-interrupts-now and test that
in lockdep.

akpm:/usr/src/25> grep LOCKDEP arch/powerpc/Kconfig 
akpm:/usr/src/25> 

losers ;)

Still, doing it for

akpm:/usr/src/25> grep -l LOCKDEP arch/*/Kconfig 
arch/arm/Kconfig
arch/avr32/Kconfig
arch/mips/Kconfig
arch/s390/Kconfig
arch/sh/Kconfig
arch/sparc64/Kconfig
arch/um/Kconfig
arch/x86/Kconfig

should give pretty good coverage.

  reply	other threads:[~2008-03-06  0:46 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-04  9:19 2.6.25-rc3-mm1 Andrew Morton
2008-03-04 11:59 ` 2.6.25-rc3-mm1 Cornelia Huck
2008-03-04 19:35   ` 2.6.25-rc3-mm1 Greg KH
2008-03-04 13:12 ` [BUG] 2.6.25-rc3-mm1 kernel panic while bootup on powerpc () Kamalesh Babulal
2008-03-04 14:40   ` Michael Neuling
2008-03-04 18:33     ` Andrew Morton
2008-03-05  8:23       ` Benjamin Herrenschmidt
2008-03-06  0:03       ` Benjamin Herrenschmidt
2008-03-06  0:44         ` Andrew Morton [this message]
2008-03-06  0:52           ` Benjamin Herrenschmidt
2008-03-04 18:36   ` Andrew Morton
2008-03-04 18:47     ` Pekka Enberg
2008-03-04 19:18     ` Pekka Enberg
2008-03-05  8:22   ` Benjamin Herrenschmidt
2008-03-04 16:35 ` 2.6.25-rc3-mm1 (IDE) Randy Dunlap
2008-03-06 21:14   ` Bartlomiej Zolnierkiewicz
2008-03-04 16:45 ` 2.6.25-rc3-mm1 (CCISS) Randy Dunlap
2008-03-04 17:02   ` Miller, Mike (OS Dev)
2008-03-04 17:14     ` Randy Dunlap
2008-03-04 18:14       ` Jens Axboe
2008-03-04 19:12 ` [PATCH 2.6.25-rc3-mm1] fix ext2 borkage Hugh Dickins
2008-03-04 19:20 ` [BUG] 2.6.25-rc3-mm1 kernel bug while running libhugetlbfs Kamalesh Babulal
2008-03-04 19:51   ` Andrew Morton
2008-03-04 22:01     ` Adam Litke
2008-03-05  7:52       ` Kamalesh Babulal
2008-03-04 20:24 ` 2.6.25-rc3-mm1 (wakeup) Randy Dunlap
2008-03-04 22:33   ` Rafael J. Wysocki
2008-03-05  7:40     ` Sam Ravnborg
2008-03-04 21:26 ` 2.6.25-rc3-mm1 (9p docs) Randy Dunlap
2008-03-04 21:43   ` Eric Van Hensbergen
2008-03-05  7:21 ` 2.6.25-rc3-mm1 - PROFILE_LIKELY redux Valdis.Kletnieks
2008-03-05 17:45   ` Andi Kleen
2008-03-05 18:02     ` Andrew Morton
2008-03-05 18:22       ` Andi Kleen
2008-03-05 22:26       ` Valdis.Kletnieks
2008-03-05 23:49         ` Andrew Morton
2008-03-05 19:59     ` Valdis.Kletnieks
2008-03-05 21:56       ` Andi Kleen
2008-03-05 10:51 ` prctl(0x8) -> EINVAL [Was: 2.6.25-rc3-mm1] Jiri Slaby
2008-03-05 10:59   ` Jiri Slaby
2008-03-05 14:06   ` Serge E. Hallyn
2008-03-05 15:18     ` Jiri Slaby
2008-03-09 16:28     ` Andrew Morgan
2008-03-05 13:04 ` 2.6.25-rc3-mm1 Pavel Emelyanov
2008-03-05 13:12   ` 2.6.25-rc3-mm1 (SYSFS=n breaks module engine) Pavel Emelyanov
2008-03-05 13:31   ` 2.6.25-rc3-mm1 Kay Sievers
2008-03-05 13:38     ` 2.6.25-rc3-mm1 Pavel Emelyanov
2008-03-05 13:54       ` 2.6.25-rc3-mm1 Kay Sievers
2008-03-05 14:28         ` 2.6.25-rc3-mm1 Pavel Emelyanov
2008-03-05 16:40   ` 2.6.25-rc3-mm1 Greg KH
2008-03-05 16:59     ` 2.6.25-rc3-mm1 Pavel Emelyanov
2008-03-05 17:07       ` 2.6.25-rc3-mm1 Greg KH
2008-03-05 21:34 ` 2.6.25-rc3-mm1 ppc64 boot hang Badari Pulavarty
2008-03-05 21:54   ` Andrew Morton
2008-03-05 22:35     ` Badari Pulavarty
2008-03-05 23:17     ` Stephen Rothwell
2008-03-07  3:58 ` 2.6.25-rc3-mm1 - BUG at system shutdown time Valdis.Kletnieks
2008-03-07  6:16   ` Andrew Morton
2008-03-07  7:52     ` Valdis.Kletnieks
2008-03-07  8:06       ` Thomas Gleixner
2008-03-07  8:23         ` Valdis.Kletnieks
2008-03-07  8:34           ` Thomas Gleixner
2008-03-07 19:30             ` Valdis.Kletnieks
2008-03-12  7:32   ` Andrew Morton
2008-03-13  2:19     ` Valdis.Kletnieks
2008-03-13  2:32       ` Andrew Morton
2008-03-13  3:57         ` Valdis.Kletnieks
2008-03-13  4:27           ` Andrew Morton
2008-03-14 18:50             ` Valdis.Kletnieks
2008-03-21 13:41       ` Ingo Molnar
2008-03-21 19:38         ` Valdis.Kletnieks
2008-03-21 19:58           ` Ingo Molnar
2008-03-21 20:05             ` Valdis.Kletnieks
2008-03-21 20:12               ` Ingo Molnar
2008-03-22  3:11                 ` Hoo-fscking-ray - (was " Valdis.Kletnieks
2008-03-22 12:09                   ` Ingo Molnar

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