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From: David Miller <davem@davemloft.net>
To: andrea@qumranet.com
Cc: a.p.zijlstra@chello.nl, davej@redhat.com, rdreier@cisco.com,
	torvalds@linux-foundation.org, jeremy@goop.org, hugh@veritas.com,
	mingo@elte.hu, akpm@linux-foundation.org,
	linux-kernel@vger.kernel.org, arjan@infradead.org
Subject: Re: [PATCH] workaround minor lockdep bug triggered by mm_take_all_locks
Date: Mon, 04 Aug 2008 14:57:13 -0700 (PDT)	[thread overview]
Message-ID: <20080804.145713.12569716.davem@davemloft.net> (raw)
In-Reply-To: <20080804210954.GC12464@duo.random>

From: Andrea Arcangeli <andrea@qumranet.com>
Date: Mon, 4 Aug 2008 23:09:54 +0200

> On Mon, Aug 04, 2008 at 10:37:22PM +0200, Peter Zijlstra wrote:
> > You're so wrong it not even funny. It reports about deadlocks before
> > they happen. All it needs is to observe a lock order violation and it
> 
> Now tell me how it helps to report them... It tells me the system has
> crashed and where, it's not like I couldn't figure it out by myself
> but just noticing nothing works and all cpus are spinning in some
> spinlock slow path and pressing sysrq+t/p.

It tells you about deadlock scenerios that you haven't even encoutered
yet.  It shows bugs for parallel code path sequences that have not
even occurred yet.

But I think you're beyond the point of being able to see why lockdep
is valuable.  So why don't we just move on.

  parent reply	other threads:[~2008-08-04 21:57 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-04 13:03 [RFC][PATCH 0/7] lockdep Peter Zijlstra
2008-08-04 13:03 ` [RFC][PATCH 1/7] lockdep: Fix combinatorial explosion in lock subgraph traversal Peter Zijlstra
2008-08-05  8:34   ` David Miller
2008-08-05  8:46     ` Peter Zijlstra
2008-08-13  3:48       ` Tim Pepper
2008-08-13 10:56         ` Ingo Molnar
2008-08-04 13:03 ` [RFC][PATCH 2/7] lockdep: lock_set_subclass - reset a held locks subclass Peter Zijlstra
2008-08-05  8:35   ` David Miller
2008-08-04 13:03 ` [RFC][PATCH 3/7] lockdep: re-annotate scheduler runqueues Peter Zijlstra
2008-08-05  8:35   ` David Miller
2008-08-04 13:03 ` [RFC][PATCH 4/7] lockdep: shrink held_lock structure Peter Zijlstra
2008-08-05 16:08   ` Peter Zijlstra
2008-08-06  7:17   ` Peter Zijlstra
2008-08-04 13:03 ` [RFC][PATCH 5/7] lockdep: map_acquire Peter Zijlstra
2008-08-04 13:03 ` [RFC][PATCH 6/7] lockdep: lock protection locks Peter Zijlstra
2008-08-04 13:03 ` [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock() Peter Zijlstra
2008-08-04 14:07   ` Roland Dreier
2008-08-04 14:19     ` Peter Zijlstra
2008-08-04 14:26       ` Roland Dreier
2008-08-04 14:32         ` Peter Zijlstra
2008-08-04 14:53           ` Dave Jones
2008-08-04 14:56             ` Peter Zijlstra
2008-08-04 16:26               ` Andrea Arcangeli
2008-08-04 16:38                 ` Peter Zijlstra
2008-08-04 17:27                   ` Andrea Arcangeli
2008-08-04 17:46                     ` Andrea Arcangeli
2008-08-04 17:57                       ` [PATCH] workaround minor lockdep bug triggered by mm_take_all_locks Andrea Arcangeli
2008-08-04 18:48                         ` Peter Zijlstra
2008-08-04 18:56                           ` Roland Dreier
2008-08-04 19:05                             ` Peter Zijlstra
2008-08-04 20:15                           ` Andrea Arcangeli
2008-08-04 20:37                             ` Peter Zijlstra
2008-08-04 21:09                               ` Andrea Arcangeli
2008-08-04 21:14                                 ` Pekka Enberg
2008-08-04 21:30                                   ` Andrea Arcangeli
2008-08-04 21:41                                     ` Andrew Morton
2008-08-04 22:12                                       ` Andrea Arcangeli
2008-08-04 21:42                                     ` Arjan van de Ven
2008-08-04 22:30                                       ` Andrea Arcangeli
2008-08-04 23:38                                         ` Arjan van de Ven
2008-08-05  0:47                                           ` Andrea Arcangeli
2008-08-04 21:27                                 ` Arjan van de Ven
2008-08-04 21:54                                   ` Andrea Arcangeli
2008-08-04 21:57                                 ` David Miller [this message]
2008-08-05  2:00                                 ` Roland Dreier
2008-08-05  2:18                                   ` Andrea Arcangeli
2008-08-05 12:02                                     ` Roland Dreier
2008-08-05 12:20                                       ` Andrea Arcangeli
2008-08-04 18:48                     ` [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock() Peter Zijlstra
2008-08-04 21:32                   ` David Miller
2008-08-04 18:06   ` Jeremy Fitzhardinge
2008-08-04 18:54     ` Peter Zijlstra
2008-08-04 19:26       ` Jeremy Fitzhardinge
2008-08-04 19:31         ` Linus Torvalds
2008-08-04 19:39           ` Peter Zijlstra
2008-08-04 20:16           ` Jeremy Fitzhardinge
2008-10-08 15:27           ` Steven Rostedt
2008-10-08 15:43             ` Linus Torvalds
2008-10-08 16:03               ` Steven Rostedt
2008-10-08 16:19                 ` Linus Torvalds
2008-10-08 16:53                   ` Steven Rostedt
2008-10-08 15:52             ` Nick Piggin
2008-10-08 17:18               ` Steven Rostedt
2008-08-07 11:25   ` Peter Zijlstra
2008-08-07 11:25 ` [RFC][PATCH 8/7] lockdep: annotate mm_take_all_locks() Peter Zijlstra
2008-08-07 11:25 ` [RFC][PATCH 9/7] mm: fix mm_take_all_locks() locking order Peter Zijlstra
2008-08-07 12:14   ` Hugh Dickins
2008-08-07 12:41     ` Peter Zijlstra
2008-08-07 13:27       ` Hugh Dickins
2008-08-07 21:46   ` Andrea Arcangeli
2008-08-08  1:34     ` Andrea Arcangeli
2008-08-08  7:16     ` Peter Zijlstra
2008-08-11 10:08 ` [RFC][PATCH 0/7] lockdep Ingo Molnar

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