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From: Jeff Garzik <jeff@garzik.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: LKML <linux-kernel@vger.kernel.org>,
	akpm@linux-foundation.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [bug] Re: [PATCH 4/12] riscom8: fix SMP brokenness
Date: Wed, 20 Feb 2008 15:37:00 -0500	[thread overview]
Message-ID: <47BC8F6C.6040403@garzik.org> (raw)
In-Reply-To: <20080207002915.GA27124@elte.hu>

Ingo Molnar wrote:
> * Jeff Garzik <jeff@garzik.org> wrote:
> 
>> After analyzing the elements that save_flags/cli/sti/restore_flags 
>> were protecting, convert their usages to a global spinlock (the 
>> easiest and most obvious next-step).  There were some usages of flags 
>> being intentionally cached, because the code already knew the state of 
>> interrupts.  These have been taken into account.
>>
>> This allows us to remove CONFIG_BROKEN_ON_SMP.  Completely untested.
> 
> regression for sale :-) The above patch, after sitting in -mm for 
> approximately 3 months, just went upstream today via commit 
> d9afa43532adf8a31b93c4c7601f and promptly broke tonight's x86.git 
> randconfig qa run via tons of these messages:
> 
> [    3.768431] BUG: scheduling while atomic: swapper/1/0x00000002
> [    3.769430] 1 lock held by swapper/1:
> [    3.770437]  #0:  (riscom_lock){--..}, at: [<80389ceb>] rc_release_drivers+0xe/0x33
> [    3.776430] Pid: 1, comm: swapper Not tainted 2.6.24 #14
> [    3.777428]  [<801167d3>] __schedule_bug+0x6e/0x75
> [    3.779427]  [<80756065>] schedule+0x35c/0x429
> [    3.781427]  [<80103a0b>] ? restore_nocheck+0x12/0x15
> [    3.784427]  [<80103a0b>] ? restore_nocheck+0x12/0x15
> [    3.786426]  [<80756381>] schedule_timeout+0x69/0xa2
> [    3.788426]  [<80758337>] ? _spin_unlock_irq+0x25/0x40
> [    3.790426]  [<80755c0e>] wait_for_common+0x96/0x10d
> [    3.792425]  [<80115edc>] ? default_wake_function+0x0/0xd
> [    3.794425]  [<80755d07>] wait_for_completion+0x12/0x14
> [    3.796425]  [<801282fe>] call_usermodehelper_exec+0x78/0x8c
> [    3.798424]  [<8015a041>] ? slob_alloc+0xd8/0x1ad
> [    3.800424]  [<80301640>] kobject_uevent_env+0x3ae/0x3c5
> [    3.802424]  [<803ac361>] ? dev_uevent+0x0/0x25a
> [    3.804424]  [<80301661>] kobject_uevent+0xa/0xc
> [    3.806423]  [<803acc06>] device_del+0x139/0x15d
> [    3.808423]  [<803acc58>] device_unregister+0x2e/0x3b
> [    3.810423]  [<803acc8e>] device_destroy+0x29/0x2f
> [    3.812422]  [<8035965f>] tty_unregister_device+0x18/0x1a
> [    3.814422]  [<8035970b>] tty_unregister_driver+0xaa/0xf6
> [    3.816422]  [<80389cf7>] rc_release_drivers+0x1a/0x33
> [    3.818421]  [<80ac5e16>] riscom8_init_module+0x4ff/0x539
> [    3.820421]  [<8012e76f>] ? ktime_get_ts+0x44/0x49
> [    3.822421]  [<80aaf701>] kernel_init+0x9a/0x263
> [    3.824421]  [<80ac5917>] ? riscom8_init_module+0x0/0x539
> [    3.827420]  [<80aaf667>] ? kernel_init+0x0/0x263
> [    3.829420]  [<8010455f>] kernel_thread_helper+0x7/0x18
> [    3.831419]  =======================

This is unfortunately very low on the priority stack.  I was a bit 
surprised when it went in, honestly, since I hadn't gotten any "it 
works" test reports yet...  but that's my fault for not keeping akpm up 
to date.

We'll want to revert this for 2.6.25 release, if it doesn't get fixed up.

	Jeff




  reply	other threads:[~2008-02-20 20:37 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-23 22:36 [PATCH 1/12] X86: fix !CONFIG_SMP warning in processor.c Jeff Garzik
2007-10-23 22:36 ` [PATCH 2/12] X86: fix nvidia HPET warning Jeff Garzik
2007-10-24  4:05   ` Jeremy Fitzhardinge
2007-10-24  6:05     ` Jeff Garzik
2007-10-24 12:03   ` Ingo Molnar
2007-10-23 22:36 ` [PATCH 3/12] ACPI sbs: fix retval warning Jeff Garzik
2007-10-30 10:31   ` Jeff Garzik
2007-10-23 22:36 ` [PATCH 4/12] riscom8: fix SMP brokenness Jeff Garzik
2007-10-24  6:47   ` Jiri Slaby
2007-10-24  6:52     ` Jeff Garzik
2007-10-24  7:44       ` Jiri Slaby
2007-10-24  7:10     ` Andrew Morton
2007-10-24  7:44       ` Jiri Slaby
2007-10-24  8:00         ` Andrew Morton
2008-02-07  0:29   ` [bug] " Ingo Molnar
2008-02-20 20:37     ` Jeff Garzik [this message]
2008-02-20 22:00       ` Alan Cox
2007-10-23 22:36 ` [PATCH 5/12] ISDN/sc: fix longstanding warning Jeff Garzik
2007-10-24  7:24   ` Karsten Keil
2007-10-23 22:36 ` [PATCH 6/12] KVM: work around SMP requirement Jeff Garzik
2007-10-23 22:44   ` Adrian Bunk
2007-10-23 22:46     ` Jeff Garzik
2007-10-24  8:36       ` Avi Kivity
2007-10-24 12:32         ` [patch] kvm: fix !SMP build error Ingo Molnar
2007-10-24 12:36           ` Ingo Molnar
2007-10-24 18:11             ` Ingo Molnar
2007-11-01  3:34               ` Randy Dunlap
2007-11-01  8:31                 ` Ingo Molnar
2007-11-01 13:10                   ` Avi Kivity
2007-11-01 14:59                     ` Ingo Molnar
2007-11-01 21:16                       ` Avi Kivity
2007-10-23 22:36 ` [PATCH 7/12] eexpress: fix !SMP unused-var warning Jeff Garzik
2007-10-23 22:36 ` [PATCH 8/12] ni5010: kill unused variable Jeff Garzik
2007-10-23 22:36 ` [PATCH 9/12] cgroup: " Jeff Garzik
2007-10-24  0:19   ` Paul Menage
2007-10-23 22:36 ` [PATCH 10/12] mac80211: fix warning created by BIT() Jeff Garzik
2007-10-23 23:15   ` Randy Dunlap
2007-10-23 22:36 ` [PATCH 11/12] NET: fix subqueue bugs Jeff Garzik
2007-10-23 22:38   ` David Miller
2007-10-23 22:40     ` Jeff Garzik
2007-10-23 22:36 ` [PATCH 12/12] sound/isa: fix printk format Jeff Garzik
2007-10-24  4:03 ` [PATCH 1/12] X86: fix !CONFIG_SMP warning in processor.c Jeremy Fitzhardinge
2007-10-24 12:01 ` Ingo Molnar
2007-10-24 16:27 ` [2.6 patch] x86/kernel/acpi/processor.c: fix SMP=n warning Adrian Bunk

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