linux-kernel - Re: [BUG 3.12.rc4] Oops: unable to handle kernel paging request during shutdown

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Message-ID: <20131026114303.GA24067@gmail.com>
Date:	Sat, 26 Oct 2013 13:43:03 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Knut Petersen <Knut_Petersen@...nline.de>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Greg KH <greg@...ah.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [BUG 3.12.rc4] Oops: unable to handle kernel paging request
 during shutdown


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Fri, Oct 25, 2013 at 11:23 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> >
> > Enable DEBUG_OBJECTS, DEBUG_OBJECTS_FREE, DEBUG_OBJECTS_TIMERS
> 
> Yes, but nobody has actually been able to trigger it with those. 
> It's pretty rare, and the debug options are so expensive that they 
> aren't reasonable to enable generally...
> 
> So we need to try to figure out how to trigger it, or narrow 
> things down some way..

If it's timing then maybe the 1 seconds delay isn't enough 
(especially if it's boot related, where we have a couple of delays 
already) - the patch below triples it.

(If the bug goes away due to some other side effect then this patch 
won't make a difference to reproducability.)

Thanks,

	Ingo

diff --git a/lib/kobject.c b/lib/kobject.c
index 084f7b1..124188f 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -595,7 +595,7 @@ static void kobject_release(struct kref *kref)
 	pr_info("kobject: '%s' (%p): %s, parent %p (delayed)\n",
 		 kobject_name(kobj), kobj, __func__, kobj->parent);
 	INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
-	schedule_delayed_work(&kobj->release, HZ);
+	schedule_delayed_work(&kobj->release, 3*HZ);
 #else
 	kobject_cleanup(kobj);
 #endif
--
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