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Re: tstile syndrome

On Thu, Aug 27, 2009 at 01:09:16PM +0200, Manuel Bouyer wrote:
> Hi,
> here's what I found so far on a server that show the tstile hang,
> with some ddb+gdb playing.
> Most processes are waiting on a tunrstile (you did know that),
> the one I started with had more than 4000 writers in the queue.
> The threads did come here though a VOP_LOCK() (you did also know that).
> This is a tunrstile for a rwlock, I found the owner of this rwlock.
> This thread is also waiting on a turnstile, but a different one,
> it also did come here though a VOP_LOCK. This is also a turnstile for a
> rwlock, which also has a owner, which also has VOP_LOCK in his stack
> trace and is waiting on a turnstile. It's also a rwlock (I checked the
> l_syncobj) but l_wchan is bogus: ffff800079ac402f, this is not a
> valid krwlock_t* (and examining memory at this address doesn't look like
> a valid krwlock_t value, and 'show lock' doens't know about it either). 
> any idea where to go from here ?

ffff800079ac402f is not a krwlock_t*, but it could be a valid
krwlock_t. Could it be that there's a place where we pass the value instead
of a pointer to the value ?

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference

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