From: Christoph Lameter <cl@linux.com>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrey Konovalov <andreyknvl@google.com>,
Alexander Potapenko <glider@google.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>
Subject: Re: Is it OK to pass non-acquired objects to kfree?
Date: Wed, 9 Sep 2015 09:36:10 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.11.1509090930510.19262@east.gentwo.org> (raw)
In-Reply-To: <CACT4Y+ZpToAmaboGDvFhgWUqtnUcJACprg=XSTkrJYE4DQ1jcA@mail.gmail.com>
On Wed, 9 Sep 2015, Dmitry Vyukov wrote:
> Yes, the object should not be accessible to other threads when kfree
> is called. But in all examples above it is accessible.
Ok. Then the code is buggy. If such an access is made then our debugging
tools will flag that.
> For example, in the last example it is still being accessed by
> kmalloc. Since there are no memory barriers, kmalloc does not
> happen-before kfree, it happens concurrently with kfree, thus memory
kmalloc cannot happen concurrently with kfree because the pointer to the
object is only available after kfree completes. There is therefore an
ordering implied by the API.
> accesses from kmalloc and kfree can be intermixed.
They cannot be mixed for the same object. kfree cannot run while kmalloc
is still in progress.
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next prev parent reply other threads:[~2015-09-09 14:36 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-08 7:51 Dmitry Vyukov
2015-09-08 14:13 ` Christoph Lameter
2015-09-08 14:41 ` Dmitry Vyukov
2015-09-08 15:13 ` Christoph Lameter
2015-09-08 15:23 ` Dmitry Vyukov
2015-09-08 15:33 ` Christoph Lameter
2015-09-08 15:37 ` Dmitry Vyukov
2015-09-08 17:09 ` Christoph Lameter
2015-09-08 19:24 ` Dmitry Vyukov
2015-09-09 14:02 ` Christoph Lameter
2015-09-09 14:19 ` Dmitry Vyukov
2015-09-09 14:36 ` Christoph Lameter [this message]
2015-09-09 15:30 ` Dmitry Vyukov
2015-09-09 15:44 ` Christoph Lameter
2015-09-09 16:09 ` Dmitry Vyukov
2015-09-09 17:56 ` Christoph Lameter
2015-09-09 18:44 ` Paul E. McKenney
2015-09-09 19:01 ` Christoph Lameter
2015-09-09 20:36 ` Paul E. McKenney
2015-09-09 23:23 ` Store Buffers (was Re: Is it OK to pass non-acquired objects to kfree?) Christoph Lameter
2015-09-10 0:08 ` Paul E. McKenney
2015-09-10 0:21 ` Christoph Lameter
2015-09-10 1:10 ` Paul E. McKenney
2015-09-10 1:47 ` Christoph Lameter
2015-09-10 7:38 ` Vlastimil Babka
2015-09-10 16:37 ` Christoph Lameter
2015-09-10 7:22 ` Vlastimil Babka
2015-09-10 16:36 ` Christoph Lameter
2015-09-09 23:31 ` Is it OK to pass non-acquired objects to kfree? Christoph Lameter
2015-09-10 9:55 ` Dmitry Vyukov
2015-09-10 10:42 ` Jesper Dangaard Brouer
2015-09-10 12:08 ` Dmitry Vyukov
2015-09-10 13:37 ` Eric Dumazet
2015-09-10 12:47 ` Vlastimil Babka
2015-09-10 13:17 ` Dmitry Vyukov
2015-09-10 17:13 ` Paul E. McKenney
2015-09-10 17:21 ` Paul E. McKenney
2015-09-10 17:26 ` Dmitry Vyukov
2015-09-10 17:44 ` Paul E. McKenney
2015-09-10 18:01 ` Christoph Lameter
2015-09-10 18:11 ` Dmitry Vyukov
2015-09-10 18:13 ` Christoph Lameter
2015-09-10 18:26 ` Dmitry Vyukov
2015-09-10 18:56 ` Paul E. McKenney
2015-09-10 22:00 ` Christoph Lameter
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