From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Christoph Lameter <cl@gentwo.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Sasha Levin <sasha.levin@oracle.com>,
Pekka Enberg <penberg@kernel.org>, Matt Mackall <mpm@selenic.com>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Jones <davej@redhat.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: slub/debugobjects: lockup when freeing memory
Date: Thu, 19 Jun 2014 13:36:59 -0700 [thread overview]
Message-ID: <20140619203659.GH4904@linux.vnet.ibm.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1406191519090.4002@gentwo.org>
On Thu, Jun 19, 2014 at 03:19:39PM -0500, Christoph Lameter wrote:
> On Thu, 19 Jun 2014, Thomas Gleixner wrote:
>
> > Well, no. Look at the callchain:
> >
> > __call_rcu
> > debug_object_activate
> > rcuhead_fixup_activate
> > debug_object_init
> > kmem_cache_alloc
> >
> > So call rcu activates the object, but the object has no reference in
> > the debug objects code so the fixup code is called which inits the
> > object and allocates a reference ....
>
> So we need to init the object in the page struct before the __call_rcu?
Good point. The patch I just sent will complain at callback-invocation
time because the debug-object information won't be present.
One way to handle this would be for rcu_do_batch() to avoid complaining
if it gets a callback that has not been through call_rcu()'s
debug_rcu_head_queue(). One way to do that would be to have an
alternative to debug_object_deactivate() that does not complain
if it is handed an unactivated object.
Another way to handle this would be for me to put the definition of
debug_rcu_head_queue() somewhere where the sl*b allocator could get
at it, and have the sl*b allocators invoke it some at initialization
and within the RCU callback.
Other thoughts?
Thanx, Paul
next prev parent reply other threads:[~2014-06-19 20:37 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-19 14:30 slub/debugobjects: lockup when freeing memory Sasha Levin
2014-06-19 15:03 ` Christoph Lameter
2014-06-19 16:52 ` Paul E. McKenney
2014-06-19 19:29 ` Thomas Gleixner
2014-06-19 20:19 ` Christoph Lameter
2014-06-19 20:28 ` Thomas Gleixner
2014-06-19 20:36 ` Paul E. McKenney [this message]
2014-08-18 16:37 ` Paul E. McKenney
2014-08-19 3:44 ` Christoph Lameter
2014-08-19 3:58 ` Paul E. McKenney
2014-08-20 2:00 ` Christoph Lameter
2014-08-20 2:31 ` Paul E. McKenney
2014-08-20 6:01 ` Christoph Lameter
2014-08-20 12:19 ` Paul E. McKenney
2014-06-19 20:29 ` Paul E. McKenney
2014-06-19 20:32 ` Sasha Levin
2014-06-19 20:39 ` Paul E. McKenney
2014-06-19 20:37 ` Thomas Gleixner
2014-06-19 20:53 ` Paul E. McKenney
2014-06-19 21:32 ` Thomas Gleixner
2014-06-19 22:04 ` Paul E. McKenney
2014-06-20 8:17 ` Thomas Gleixner
2014-06-20 15:40 ` Paul E. McKenney
2014-07-12 18:03 ` Sasha Levin
2014-07-12 19:33 ` Paul E. McKenney
2014-06-20 14:30 ` Christoph Lameter
2014-06-19 20:42 ` Sasha Levin
2014-06-19 20:53 ` Paul E. McKenney
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