From: Steven Rostedt <rostedt@goodmis.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Clark Williams <williams@redhat.com>,
"Luis Claudio R. Goncalves" <lclaudio@uudg.org>
Subject: Re: [BUG] signal: sighand unprotected when accessed by /proc
Date: Tue, 3 Jun 2014 16:25:14 -0400 [thread overview]
Message-ID: <20140603162514.7b11f3ea@gandalf.local.home> (raw)
In-Reply-To: <20140603200938.GA3384@redhat.com>
On Tue, 3 Jun 2014 22:09:38 +0200
Oleg Nesterov <oleg@redhat.com> wrote:
> > Now, if that lock is released and reused (I didn't trace other tasks
> > allocating these locks), it reinitializes the lock->wait_list.
>
> How? From where? This should be done by sighand_ctor() only?
This looks definitely like an -rt only bug and it's an obvious one at
that :-p
Looking in mm/slub.c: slab_alloc_node() we have this:
if (unlikely(gfpflags & __GFP_ZERO) && object)
memset(object, 0, s->object_size);
#ifdef CONFIG_PREEMPT_RT_FULL
if (unlikely(s->ctor) && object)
s->ctor(object);
#endif
slab_post_alloc_hook(s, gfpflags, object);
return object;
}
We call the ctor on the object when it is allocated, not when the page
is created.
Doh! I guess we now know why we shouldn't do that.
-- Steve
next prev parent reply other threads:[~2014-06-03 20:25 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-03 17:02 [BUG] signal: sighand unprotected when accessed by /proc Steven Rostedt
2014-06-03 17:26 ` Oleg Nesterov
2014-06-03 18:03 ` Linus Torvalds
2014-06-03 20:01 ` Oleg Nesterov
2014-06-03 20:03 ` Oleg Nesterov
2014-06-06 20:33 ` Paul E. McKenney
2014-06-08 13:07 ` safety of *mutex_unlock() (Was: [BUG] signal: sighand unprotected when accessed by /proc) Oleg Nesterov
2014-06-09 16:26 ` Paul E. McKenney
2014-06-09 18:15 ` Oleg Nesterov
2014-06-09 18:29 ` Steven Rostedt
2014-06-09 18:51 ` Linus Torvalds
2014-06-09 19:41 ` Steven Rostedt
2014-06-10 8:53 ` Thomas Gleixner
2014-06-10 16:57 ` Oleg Nesterov
2014-06-10 18:08 ` Thomas Gleixner
2014-06-10 18:13 ` Steven Rostedt
2014-06-10 20:05 ` Thomas Gleixner
2014-06-10 20:13 ` Thomas Gleixner
2014-06-11 15:52 ` Paul E. McKenney
2014-06-11 17:07 ` Oleg Nesterov
2014-06-11 17:17 ` Oleg Nesterov
2014-06-11 17:29 ` Paul E. McKenney
2014-06-11 17:59 ` Oleg Nesterov
2014-06-11 19:56 ` Paul E. McKenney
2014-06-12 17:28 ` Oleg Nesterov
2014-06-12 20:35 ` Paul E. McKenney
2014-06-12 21:40 ` Thomas Gleixner
2014-06-12 22:27 ` Paul E. McKenney
2014-06-12 23:19 ` Paul E. McKenney
2014-06-13 15:08 ` Oleg Nesterov
2014-06-15 5:40 ` Paul E. McKenney
2014-06-17 18:57 ` Paul E. McKenney
2014-06-18 16:43 ` Oleg Nesterov
2014-06-18 16:53 ` Steven Rostedt
2014-06-21 19:54 ` Thomas Gleixner
2014-06-18 17:00 ` Paul E. McKenney
2014-06-13 14:55 ` Oleg Nesterov
2014-06-13 16:10 ` Thomas Gleixner
2014-06-13 16:19 ` Oleg Nesterov
2014-06-13 14:52 ` Oleg Nesterov
2014-06-11 17:27 ` Paul E. McKenney
2014-06-10 17:07 ` Oleg Nesterov
2014-06-10 17:51 ` Thomas Gleixner
2014-06-10 12:56 ` Paul E. McKenney
2014-06-10 14:48 ` Peter Zijlstra
2014-06-10 15:18 ` Paul E. McKenney
2014-06-10 15:35 ` Linus Torvalds
2014-06-10 16:15 ` Paul E. McKenney
2014-06-09 19:04 ` Oleg Nesterov
2014-06-10 8:37 ` Peter Zijlstra
2014-06-10 12:52 ` Paul E. McKenney
2014-06-10 13:01 ` Peter Zijlstra
2014-06-10 14:36 ` Paul E. McKenney
2014-06-10 15:20 ` Paul E. McKenney
2014-06-03 20:05 ` [BUG] signal: sighand unprotected when accessed by /proc Steven Rostedt
2014-06-03 20:09 ` Oleg Nesterov
2014-06-03 20:15 ` Steven Rostedt
2014-06-03 20:25 ` Steven Rostedt [this message]
2014-06-03 21:12 ` Thomas Gleixner
2014-06-03 18:05 ` Steven Rostedt
2014-06-03 19:25 ` Oleg Nesterov
2014-06-04 1:16 ` Steven Rostedt
2014-06-04 16:31 ` Oleg Nesterov
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