Re: 2.6.24-rc2-mm1: kcryptd vs lockdep

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To: Ingo Molnar <mingo@...>
Cc: Andrew Morton <akpm@...>, Linux Kernel list <linux-kernel@...>
Date: Monday, November 19, 2007 - 3:34 pm

On Nov 19, 2007 8:56 AM, Ingo Molnar <mingo@elte.hu> wrote:

I have SLUB_DEBUG=y, but not SLUB_DEBUG_ON.
But apart from this message I did not the anything in the syslog.
It seems to not be onetime event, as one the third boot it happend
again. Stacktrace was identical.
Sadly trying 3 boots with slub_debug=FZP and another one with only F
did not trigger it.

But I don't think kcryptd is freeing a bio at that point.
The message said about the freed lock: (kcryptd){--..}, at: [<ffffffff80247dd9>]
(gdb) list *0xffffffff80247dd9
0xffffffff80247dd9 is in run_workqueue (include/asm/bitops_64.h:69).
64       * you should call smp_mb__before_clear_bit() and/or
smp_mb__after_clear_bit()
65       * in order to ensure changes are visible on other processors.
66       */
67      static inline void clear_bit(int nr, volatile void *addr)
68      {
69              __asm__ __volatile__( LOCK_PREFIX
70                      "btrl %1,%0"
71                      :ADDR
72                      :"dIr" (nr));
73      }
increasing the addr a little bit shows:
(gdb) list *0xffffffff80247ddf
0xffffffff80247ddf is in run_workqueue (kernel/workqueue.c:275).
270                     list_del_init(cwq->worklist.next);
271                     spin_unlock_irq(&cwq->lock);
272
273                     BUG_ON(get_wq_data(work) != cwq);
274                     work_clear_pending(work);
275                     lock_acquire(&cwq->wq->lockdep_map, 0, 0, 0,
2, _THIS_IP_);
276                     lock_acquire(&lockdep_map, 0, 0, 0, 2, _THIS_IP_);
277                     f(work);
278                     lock_release(&lockdep_map, 1, _THIS_IP_);
279                     lock_release(&cwq->wq->lockdep_map, 1, _THIS_IP_);


Above this acquire/release sequence is the following comment:
#ifdef CONFIG_LOCKDEP
                /*
                 * It is permissible to free the struct work_struct
                 * from inside the function that is called from it,
                 * this we need to take into account for lockdep too.
                 * To avoid bogus "held lock freed" warnings as well
                 * as problems when looking into work->lockdep_map,
                 * make a copy and use that here.
                 */
                struct lockdep_map lockdep_map = work->lockdep_map;
#endif

Did something trigger this anyway?

Anything I could try, apart from more boots with slub_debug=F?

Torsten
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Messages in current thread:
2.6.24-rc2-mm1: kcryptd vs lockdep, Torsten Kaiser, (Mon Nov 19, 3:23 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Ingo Molnar, (Mon Nov 19, 3:56 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Torsten Kaiser, (Mon Nov 19, 3:34 pm)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Milan Broz, (Mon Nov 19, 5:00 pm)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Torsten Kaiser, (Fri Nov 23, 6:42 pm)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Alasdair G Kergon, (Sat Nov 24, 12:13 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Alasdair G Kergon, (Fri Nov 23, 11:49 pm)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Torsten Kaiser, (Sat Nov 24, 12:57 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Alasdair G Kergon, (Sat Nov 24, 12:03 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Herbert Xu, (Sat Nov 24, 2:38 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Torsten Kaiser, (Tue Nov 20, 2:55 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Torsten Kaiser, (Fri Nov 23, 6:21 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Milan Broz, (Tue Nov 20, 10:40 am)
Re: 2.6.24-rc2-mm1: kcryptd vs lockdep, Alasdair G Kergon, (Tue Nov 20, 7:36 pm)