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SubjectRe: WARNING: at kernel/lockdep.c:690 __lock_acquire+0x168/0x164b()
On Sun, 16 Oct 2011, Borislav Petkov wrote:

> > I think this is a problem with lockdep itself, could you try reverting
> > f59de8992aa6 ("lockdep: Clear whole lockdep_map on initialization") if
> > this reliably happens everytime you reboot (lockdep will only emit this
> > once and then will suppress future warnings until the next boot)?
> >
> > I think the new memset() is inadvertently clearing the name for
> > double_unlock_balance().
>
> Great,
>
> so I'm not the only one seeing the above:
> http://marc.info/?l=linux-kernel&m=131468805610527
>
> Due to it being very hard to reproduce, we dismissed it then as a
> possible hw corruption.
>
> But yeah, it looks like I have triggered it on -rc9 too, just the
> other day. Oh, and I see -rc6 and -rc8 warnings in the logs too. Ok,
> correction, not that hard to trigger.
>

Could you try to revert f59de8992aa6 ("lockdep: Clear whole lockdep_map on
initialization") with this patch and see if it helps? Thanks.
---
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2874,7 +2874,10 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
void lockdep_init_map(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, int subclass)
{
- memset(lock, 0, sizeof(*lock));
+ int i;
+
+ for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
+ lock->class_cache[i] = NULL;

#ifdef CONFIG_LOCK_STAT
lock->cpu = raw_smp_processor_id();

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