From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
rostedt <rostedt@goodmis.org>, dhowells <dhowells@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: lockdep trace from posix timers
Date: Mon, 20 Aug 2012 16:55:50 +0200 [thread overview]
Message-ID: <20120820145550.GA18499@redhat.com> (raw)
In-Reply-To: <1345446957.23018.14.camel@twins>
On 08/20, Peter Zijlstra wrote:
>
> On Fri, 2012-08-17 at 17:14 +0200, Oleg Nesterov wrote:
> > I still think that task_work_add() should synhronize with exit_task_work()
> > itself and fail if necessary. But I wasn't able to convince Al ;)
>
> I'm not at all sure how that relates to needing task_lock() in the
> keyctl stuff.
To serialize with exit_mm() which clears ->mm.
We shouldn't do task_work_add(task) if the exiting task has already
passed exit_task_work(). There is no way to do this after ed3e694d7
(and I think this is wrong), so keyctl relies on the fact that
exit_task_work() is called after exit_mm().
> Also, can't task_work use llist stuff? That would also avoid using
> ->pi_lock.
Not sure.... task_work_add/run can use cmpxchg, but _cancel can't.
Oleg.
next prev parent reply other threads:[~2012-08-20 14:59 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-24 20:36 lockdep trace from posix timers Dave Jones
2012-07-27 16:20 ` Dave Jones
2012-08-16 12:54 ` Ming Lei
2012-08-16 14:03 ` Dave Jones
2012-08-16 18:07 ` Peter Zijlstra
2012-08-17 15:14 ` Oleg Nesterov
2012-08-17 15:17 ` Oleg Nesterov
2012-08-17 16:40 ` task_work_add() should not succeed unconditionally (Was: lockdep trace from posix timers) Oleg Nesterov
2012-08-20 7:15 ` lockdep trace from posix timers Peter Zijlstra
2012-08-20 11:44 ` Peter Zijlstra
2012-08-20 11:46 ` Peter Zijlstra
2012-08-20 11:50 ` Peter Zijlstra
2012-08-20 12:19 ` Steven Rostedt
2012-08-20 12:20 ` Peter Zijlstra
2012-08-20 14:59 ` Oleg Nesterov
2012-08-20 15:10 ` Peter Zijlstra
2012-08-20 15:27 ` Peter Zijlstra
2012-08-20 15:32 ` Oleg Nesterov
2012-08-20 15:46 ` Peter Zijlstra
2012-08-20 15:58 ` Oleg Nesterov
2012-08-20 16:03 ` Peter Zijlstra
2012-08-20 15:05 ` Oleg Nesterov
2012-08-20 15:12 ` Peter Zijlstra
2012-08-20 15:41 ` Oleg Nesterov
2012-08-20 15:56 ` Peter Zijlstra
2012-08-20 16:10 ` Oleg Nesterov
2012-08-20 16:19 ` Peter Zijlstra
2012-08-20 16:23 ` Oleg Nesterov
2012-08-21 18:27 ` Oleg Nesterov
2012-08-21 18:34 ` Oleg Nesterov
2012-08-24 18:56 ` Oleg Nesterov
2012-08-26 19:11 ` [PATCH 0/4] (Was: lockdep trace from posix timers) Oleg Nesterov
2012-08-26 19:12 ` [PATCH 1/4] task_work: make task_work_add() lockless Oleg Nesterov
2012-09-14 6:08 ` [tip:core/urgent] task_work: Make " tip-bot for Oleg Nesterov
2012-09-24 19:27 ` [PATCH 1/4] task_work: make " Geert Uytterhoeven
2012-09-24 20:37 ` Oleg Nesterov
2012-08-26 19:12 ` [PATCH 2/4] task_work: task_work_add() should not succeed after exit_task_work() Oleg Nesterov
2012-09-14 6:09 ` [tip:core/urgent] " tip-bot for Oleg Nesterov
2012-08-26 19:12 ` [PATCH 3/4] task_work: revert d35abdb2 "hold task_lock around checks in keyctl" Oleg Nesterov
2012-09-14 6:10 ` [tip:core/urgent] task_work: Revert " hold " tip-bot for Oleg Nesterov
2012-08-26 19:12 ` [PATCH 4/4] task_work: simplify the usage in ptrace_notify() and get_signal_to_deliver() Oleg Nesterov
2012-09-14 6:11 ` [tip:core/urgent] task_work: Simplify " tip-bot for Oleg Nesterov
2012-09-06 18:01 ` [PATCH 0/4] (Was: lockdep trace from posix timers) Oleg Nesterov
2012-09-06 18:35 ` Peter Zijlstra
2012-09-07 13:13 ` Oleg Nesterov
2012-08-28 16:29 ` lockdep trace from posix timers Peter Zijlstra
2012-08-28 17:01 ` Oleg Nesterov
2012-08-28 17:12 ` Oleg Nesterov
2012-08-28 17:28 ` Peter Zijlstra
2012-08-29 15:25 ` Oleg Nesterov
2012-08-20 14:55 ` Oleg Nesterov [this message]
2012-08-20 15:43 ` Oleg Nesterov
2012-08-20 15:48 ` Peter Zijlstra
2012-08-20 15:58 ` Oleg Nesterov
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