Messages in this thread Patch in this message | | | Date | Fri, 20 May 2011 08:55:11 -0700 | From | Darren Hart <> | Subject | Re: kernel 2.6.39 (user mode linux) crashes (2.6.38 works fine) |
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On 05/20/2011 12:56 AM, richard -rw- weinberger wrote: > 2011/5/20 Toralf Förster <toralf.foerster@gmx.de>: >> ... >> Kernel panic - not syncing: Kernel mode fault at addr 0x0, ip 0x80a9f6b > > Looks like a NULL-pointer bug. > What code is at address 80a9f6b? > Use "objdump -d -S | less" to find it. > Please note, kernel binary and log message have to match! > >> The file /var/log/messages of the UML says : >> >> 2011-05-20T09:33:03.455+02:00 n22_uml kernel: ------------[ cut here ]------------ >> 2011-05-20T09:33:03.455+02:00 n22_uml kernel: WARNING: at kernel/futex.c:789 wake_futex+0x28/0x60() > > Is this really 2.6.39? > Line 789 contains no WARN*(). > http://lxr.linux.no/#linux+v2.6.39/kernel/futex.c#L789 >
I suspect Toralf is hitting the WARN_ON in __unqueue_futex:
if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr) || plist_node_empty(&q->list)))
Toralf, can you instrument that let us know which of conditions is triggering the WARN_ON? Something like the following should be adequate to get you the line number. I suspect it is plist_node_empty give the git bisect results you reported.
diff --git a/kernel/futex.c b/kernel/futex.c index abd5324..7f31bca 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -782,8 +782,11 @@ static void __unqueue_futex(struct futex_q *q) { struct futex_hash_bucket *hb;
- if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr) - || plist_node_empty(&q->list))) + if (WARN_ON(!q->lock_ptr)) + return; + if (!spin_is_locked(q->lock_ptr)) + return; + if (plist_node_empty(&q->list)) return;
hb = container_of(q->lock_ptr, struct futex_hash_bucket, lock);
-- Darren Hart Intel Open Source Technology Center Yocto Project - Linux Kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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