Messages in this thread | | | Subject | Re: processes hung after sys_renameat, and 'missing' processes | From | Peter Zijlstra <> | Date | Mon, 04 Jun 2012 11:29:17 +0200 |
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On Sun, 2012-06-03 at 17:16 -0700, Linus Torvalds wrote: > On Sun, Jun 3, 2012 at 5:00 PM, Dave Jones <davej@redhat.com> wrote: > > > > sysrq-d: http://fpaste.org/ow9O/ > > Ugh. I'm adding PeterZ to the cc, just to see if he can make more sense of it. > > Peter, is there no way to make the lock thing print not just the lock > class name, but also the pointer to the actual *instance* of the lock > held?
Sorta, we have a pointer to the struct lockdep_map inside whatever lock type. But we don't have the lock type so we cannot actually provide the pointer to the spinlock_t struct mutex etc..
> Also, it's a bit unclear to me, but I *think* that most of those users > don't actually "hold" the lock - they are waiting for it. Yes/no?
Yes, this is waiting to acquire, lockdep started out with 2 hooks, one before the actual acquire and one on release. Its done before the actual acquire so we can warn before we lock up in case of an actual deadlock.
> Does > the lockdep information have the capability to distinguish between > "waiting for" vs "actually successfully owns the lock"?
Sometimes.. when build with lockstat we have enough hooks to do this. I suppose I could make all those hooks available for all of lockdep and track the per lock state more accurate in order to improve this printout.
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