From: Dan Carpenter <dan.carpenter@oracle.com>
To: Valdis.Kletnieks@vt.edu
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jiri Kosina <jkosina@suse.cz>, Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Theodore Ts'o <tytso@mit.edu>
Subject: Re: [PATCH] mm/sl[aou]b: make kfree() aware of error pointers
Date: Wed, 10 Sep 2014 09:51:29 +0300 [thread overview]
Message-ID: <20140910065129.GN6549@mwanda> (raw)
In-Reply-To: <113623.1410326115@turing-police.cc.vt.edu>
On Wed, Sep 10, 2014 at 01:15:15AM -0400, Valdis.Kletnieks@vt.edu wrote:
> On Tue, 09 Sep 2014 16:21:14 -0700, Andrew Morton said:
> > On Tue, 9 Sep 2014 23:25:28 +0200 (CEST) Jiri Kosina <jkosina@suse.cz> wrote:
> > kfree() is quite a hot path to which this will add overhead. And we
> > have (as far as we know) no code which will actually use this at
> > present.
>
> We already do a check for ZERO_SIZE_PTR, and given that dereferencing *that* is
> instant death for the kernel, and we see it very rarely, I'm going to guess
> that IS_ERR(ptr) *has* to be true more often than ZERO_SIZE_PTR, and thus even
> more advantageous to short-circuit.
ZERO_SIZE_PTR is sort of common.
ZERO_SIZE_PTR is an mm abstraction and kfree() and ksize() are basically
the only places where we need to test for it. Also friends of kfree()
like jbd2_journal_free_transaction().
regards,
dan carpenter
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WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Valdis.Kletnieks@vt.edu
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jiri Kosina <jkosina@suse.cz>, Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Theodore Ts'o" <tytso@mit.edu>
Subject: Re: [PATCH] mm/sl[aou]b: make kfree() aware of error pointers
Date: Wed, 10 Sep 2014 09:51:29 +0300 [thread overview]
Message-ID: <20140910065129.GN6549@mwanda> (raw)
In-Reply-To: <113623.1410326115@turing-police.cc.vt.edu>
On Wed, Sep 10, 2014 at 01:15:15AM -0400, Valdis.Kletnieks@vt.edu wrote:
> On Tue, 09 Sep 2014 16:21:14 -0700, Andrew Morton said:
> > On Tue, 9 Sep 2014 23:25:28 +0200 (CEST) Jiri Kosina <jkosina@suse.cz> wrote:
> > kfree() is quite a hot path to which this will add overhead. And we
> > have (as far as we know) no code which will actually use this at
> > present.
>
> We already do a check for ZERO_SIZE_PTR, and given that dereferencing *that* is
> instant death for the kernel, and we see it very rarely, I'm going to guess
> that IS_ERR(ptr) *has* to be true more often than ZERO_SIZE_PTR, and thus even
> more advantageous to short-circuit.
ZERO_SIZE_PTR is sort of common.
ZERO_SIZE_PTR is an mm abstraction and kfree() and ksize() are basically
the only places where we need to test for it. Also friends of kfree()
like jbd2_journal_free_transaction().
regards,
dan carpenter
next prev parent reply other threads:[~2014-09-10 6:51 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-09 21:25 [PATCH] mm/sl[aou]b: make kfree() aware of error pointers Jiri Kosina
2014-09-09 21:25 ` Jiri Kosina
2014-09-09 23:21 ` Andrew Morton
2014-09-09 23:21 ` Andrew Morton
2014-09-10 5:05 ` Jiri Kosina
2014-09-10 5:05 ` Jiri Kosina
2014-09-10 5:11 ` Andrew Morton
2014-09-10 5:11 ` Andrew Morton
2014-09-10 6:36 ` Dan Carpenter
2014-09-10 6:36 ` Dan Carpenter
2014-09-10 13:56 ` Theodore Ts'o
2014-09-10 13:56 ` Theodore Ts'o
2014-09-10 14:27 ` Dave Jones
2014-09-10 14:27 ` Dave Jones
2014-09-10 14:07 ` Theodore Ts'o
2014-09-10 14:07 ` Theodore Ts'o
2014-09-10 14:24 ` Jiri Kosina
2014-09-10 14:24 ` Jiri Kosina
2014-09-10 14:33 ` Andrey Ryabinin
2014-09-10 14:33 ` Andrey Ryabinin
2014-09-10 14:42 ` Jiri Kosina
2014-09-10 14:42 ` Jiri Kosina
2014-09-10 15:43 ` Christoph Lameter
2014-09-10 15:43 ` Christoph Lameter
2014-09-10 14:26 ` Jiri Kosina
2014-09-10 14:26 ` Jiri Kosina
2014-09-10 15:21 ` Dan Carpenter
2014-09-10 15:21 ` Dan Carpenter
2014-09-10 15:28 ` Jiri Kosina
2014-09-10 15:28 ` Jiri Kosina
2014-09-10 15:53 ` Dan Carpenter
2014-09-10 15:53 ` Dan Carpenter
2014-09-10 19:40 ` Theodore Ts'o
2014-09-10 19:40 ` Theodore Ts'o
2014-09-11 14:14 ` Rasmus Villemoes
2014-09-11 14:14 ` Rasmus Villemoes
2014-09-10 14:22 ` Christoph Lameter
2014-09-10 14:22 ` Christoph Lameter
2014-09-10 5:15 ` Valdis.Kletnieks
2014-09-10 6:51 ` Dan Carpenter [this message]
2014-09-10 6:51 ` Dan Carpenter
2014-09-10 13:59 ` Christoph Lameter
2014-09-10 13:59 ` Christoph Lameter
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