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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	akpm@linux-foundation.org
Subject: Re: [RFC 0/4] CONFIG_STABLE to switch off development checks
Date: Sat, 02 Jun 2007 09:28:38 -0700	[thread overview]
Message-ID: <46619AB6.5060606@goop.org> (raw)
In-Reply-To: <1180797790.18535.6.camel@kleikamp.austin.ibm.com>

Dave Kleikamp wrote:
> I'm on Christoph's side here.  I don't think it makes sense for any code
> to ask to allocate zero bytes of memory and expect valid memory to be
> returned.
>   

Yes, everyone agrees on that.  If you do kmalloc(0), its never OK to
dereference the result.  The question is whether kmalloc(0) should complain.

> Would a compromise be to return a pointer to some known invalid region?
> This way the kmalloc(0) call would appear successful to the caller, but
> any access to the memory would result in an exception.
>   

Yes, that's what Christoph has posted.  I'm slightly concerned about
kmalloc() returning the same non-NULL address multiple times, but it
seems sound otherwise.

    J

WARNING: multiple messages have this Message-ID (diff)
From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	akpm@linux-foundation.org
Subject: Re: [RFC 0/4] CONFIG_STABLE to switch off development checks
Date: Sat, 02 Jun 2007 09:28:38 -0700	[thread overview]
Message-ID: <46619AB6.5060606@goop.org> (raw)
In-Reply-To: <1180797790.18535.6.camel@kleikamp.austin.ibm.com>

Dave Kleikamp wrote:
> I'm on Christoph's side here.  I don't think it makes sense for any code
> to ask to allocate zero bytes of memory and expect valid memory to be
> returned.
>   

Yes, everyone agrees on that.  If you do kmalloc(0), its never OK to
dereference the result.  The question is whether kmalloc(0) should complain.

> Would a compromise be to return a pointer to some known invalid region?
> This way the kmalloc(0) call would appear successful to the caller, but
> any access to the memory would result in an exception.
>   

Yes, that's what Christoph has posted.  I'm slightly concerned about
kmalloc() returning the same non-NULL address multiple times, but it
seems sound otherwise.

    J

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  reply	other threads:[~2007-06-02 16:28 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-31  0:20 [RFC 0/4] CONFIG_STABLE to switch off development checks clameter
2007-05-31  0:20 ` clameter
2007-05-31  0:20 ` [RFC 1/4] CONFIG_STABLE: Define it clameter
2007-05-31  0:20   ` clameter
2007-05-31  0:35   ` young dave
2007-05-31  0:35     ` young dave
2007-05-31  0:49     ` Christoph Lameter
2007-05-31  0:49       ` Christoph Lameter
2007-06-01 18:08       ` Dave Jones
2007-06-01 18:08         ` Dave Jones
2007-06-01 18:25         ` Christoph Lameter
2007-06-01 18:25           ` Christoph Lameter
2007-05-31  8:54   ` Stefan Richter
2007-05-31  8:54     ` Stefan Richter
2007-05-31  9:03     ` David Miller
2007-05-31  9:03       ` David Miller, Stefan Richter
2007-05-31  9:03     ` Stefan Richter
2007-05-31  9:03       ` Stefan Richter
2007-05-31 21:11   ` Andrew Morton
2007-05-31 21:11     ` Andrew Morton
2007-05-31 21:14     ` Christoph Lameter
2007-05-31 21:14       ` Christoph Lameter
2007-05-31 21:30     ` Sam Ravnborg
2007-05-31 21:30       ` Sam Ravnborg
2007-06-01 18:02       ` Dave Jones
2007-06-01 18:02         ` Dave Jones
2007-06-01 20:22         ` Sam Ravnborg
2007-06-01 20:22           ` Sam Ravnborg
2007-06-01 20:30           ` Dave Jones
2007-06-01 20:30             ` Dave Jones
2007-06-01 20:55             ` Sam Ravnborg
2007-06-01 20:55               ` Sam Ravnborg
2007-06-01 20:25     ` Sam Ravnborg
2007-06-01 20:25       ` Sam Ravnborg
2007-07-20 10:41   ` Satyam Sharma
2007-07-20 10:41     ` Satyam Sharma
2007-07-20 11:09     ` Chris Snook
2007-07-20 11:09       ` Chris Snook
2007-07-20 11:27       ` Satyam Sharma
2007-07-20 11:27         ` Satyam Sharma
2007-07-20 11:34         ` Chris Snook
2007-07-20 11:34           ` Chris Snook
2007-07-20 11:40           ` Satyam Sharma
2007-07-20 11:40             ` Satyam Sharma
2007-07-20 11:50             ` Chris Snook
2007-07-20 11:50               ` Chris Snook
2007-07-20 16:48               ` Stefan Richter
2007-07-20 16:48                 ` Stefan Richter
2007-07-20 16:28     ` Stefan Richter
2007-07-20 16:28       ` Stefan Richter
2007-07-20 16:36       ` Stefan Richter
2007-07-20 16:36         ` Stefan Richter
2007-07-20 19:09         ` Chuck Ebbert
2007-07-20 19:09           ` Chuck Ebbert
2007-05-31  0:20 ` [RFC 2/4] CONFIG_STABLE: Switch off kmalloc(0) tests in slab allocators clameter
2007-05-31  0:20   ` clameter
2007-05-31 19:51   ` Zach Brown
2007-05-31 19:51     ` Zach Brown
2007-05-31 22:37     ` Andi Kleen
2007-05-31 22:37       ` Andi Kleen
2007-05-31  0:20 ` [RFC 3/4] CONFIG_STABLE: Switch off SLUB banner clameter
2007-05-31  0:20   ` clameter
2007-05-31  0:20 ` [RFC 4/4] CONFIG_STABLE: SLUB: Prefer object corruption over failure clameter
2007-05-31  0:20   ` clameter
2007-06-01 14:55 ` [RFC 0/4] CONFIG_STABLE to switch off development checks Jeremy Fitzhardinge
2007-06-01 14:55   ` Jeremy Fitzhardinge
2007-06-01 18:38   ` Christoph Lameter
2007-06-01 18:38     ` Christoph Lameter
2007-06-01 18:58     ` Jeremy Fitzhardinge
2007-06-01 18:58       ` Jeremy Fitzhardinge
2007-06-01 20:59       ` Christoph Lameter
2007-06-01 20:59         ` Christoph Lameter
2007-06-01 21:24         ` Jeremy Fitzhardinge
2007-06-01 21:24           ` Jeremy Fitzhardinge
2007-06-02 15:23       ` Dave Kleikamp
2007-06-02 15:23         ` Dave Kleikamp
2007-06-02 16:28         ` Jeremy Fitzhardinge [this message]
2007-06-02 16:28           ` Jeremy Fitzhardinge
2007-06-04  1:03           ` Dave Kleikamp
2007-06-04  1:03             ` Dave Kleikamp
     [not found] <fa.UBCbBXgIW93M6j2F+d+umQ5+v9I@ifi.uio.no>
     [not found] ` <fa.iaekQW/Par/E6eIpnL0NjEdCUxc@ifi.uio.no>
     [not found]   ` <fa.2BlkzuhauAATrsG1MYhPMeWMhPM@ifi.uio.no>
     [not found]     ` <fa.o9WA1K75HxwNnBEQDyoQMfWVpiQ@ifi.uio.no>
     [not found]       ` <fa.wiSgrIhkRNkkC7Wh6Bt3BY4z7BM@ifi.uio.no>
2007-06-05  0:38         ` Robert Hancock
2007-06-05  0:38           ` Robert Hancock

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