Re: [PATCH] workaround minor lockdep bug triggered by mm_take_all_locks

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To: Roland Dreier <rdreier@...>
Cc: Peter Zijlstra <a.p.zijlstra@...>, Dave Jones <davej@...>, Linus Torvalds <torvalds@...>, David Miller <davem@...>, <jeremy@...>, <hugh@...>, <mingo@...>, <akpm@...>, <linux-kernel@...>, arjan <arjan@...>
Date: Monday, August 4, 2008 - 10:18 pm

On Mon, Aug 04, 2008 at 07:00:03PM -0700, Roland Dreier wrote:

Thanks a lot for the detailed explanation of check_noncircular. I
agree check_noncircular is surely a good argument not to get rid of
prove-locking as a whole. But check_noncircular is also a red-herring
in this context. It's not check_noncircular trapping here,
check_deadlock traps with false positives instead. The question is
what are those false positives buying us? To avoid a developer to
press sysrq+p or break on kgdb?

Let's focus on check_deadlock->print_deadlock_bug and somebody who's
not beyond the point please explain what print_deadlock_bug reports
that does not actually occur and why it's a good idea to change the
common code to accommodate for its false positives instead of getting
rid of it for good.
--
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Messages in current thread:
[RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Mon Aug 4, 9:03 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Thu Aug 7, 7:25 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Jeremy Fitzhardinge, (Mon Aug 4, 2:06 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Mon Aug 4, 2:54 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Jeremy Fitzhardinge, (Mon Aug 4, 3:26 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Linus Torvalds, (Mon Aug 4, 3:31 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Steven Rostedt, (Wed Oct 8, 11:27 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Nick Piggin, (Wed Oct 8, 11:52 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Steven Rostedt, (Wed Oct 8, 1:18 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Linus Torvalds, (Wed Oct 8, 11:43 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Steven Rostedt, (Wed Oct 8, 12:03 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Linus Torvalds, (Wed Oct 8, 12:19 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Steven Rostedt, (Wed Oct 8, 12:53 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Jeremy Fitzhardinge, (Mon Aug 4, 4:16 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Mon Aug 4, 3:39 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Roland Dreier, (Mon Aug 4, 10:07 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Mon Aug 4, 10:19 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Roland Dreier, (Mon Aug 4, 10:26 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Mon Aug 4, 10:32 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Dave Jones, (Mon Aug 4, 10:53 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Mon Aug 4, 10:56 am)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Andrea Arcangeli, (Mon Aug 4, 12:26 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Mon Aug 4, 12:38 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), David Miller, (Mon Aug 4, 5:32 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Andrea Arcangeli, (Mon Aug 4, 1:27 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Peter Zijlstra, (Mon Aug 4, 2:48 pm)
Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock(), Andrea Arcangeli, (Mon Aug 4, 1:46 pm)
Re: [PATCH] workaround minor lockdep bug triggered by mm_tak..., Andrea Arcangeli, (Mon Aug 4, 10:18 pm)