From: Colin Walters <walters@verbum.org>
To: Jan Kara <jack@suse.cz>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-ia64@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
dsterba@suse.cz, ptesarik@suse.cz, rguenther@suse.de,
gcc@gcc.gnu.org
Subject: Re: Memory corruption due to word sharing
Date: Wed, 01 Feb 2012 16:37:45 +0000 [thread overview]
Message-ID: <1328114266.5355.44.camel@lenny> (raw)
In-Reply-To: <20120201151918.GC16714@quack.suse.cz>
On Wed, 2012-02-01 at 16:19 +0100, Jan Kara wrote:
> I've raised the issue with our GCC guys and they said to me that: "C does
> not provide such guarantee, nor can you reliably lock different
> structure fields with different locks if they share naturally aligned
> word-size memory regions. The C++11 memory model would guarantee this,
> but that's not implemented nor do you build the kernel with a C++11
> compiler."
That's interesting. So it seems like there are two solutions:
1) Use the same lock for a given bitfield
2) Split up the bitfield into different words
WARNING: multiple messages have this Message-ID (diff)
From: Colin Walters <walters@verbum.org>
To: Jan Kara <jack@suse.cz>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-ia64@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
dsterba@suse.cz, ptesarik@suse.cz, rguenther@suse.de,
gcc@gcc.gnu.org
Subject: Re: Memory corruption due to word sharing
Date: Wed, 01 Feb 2012 11:37:45 -0500 [thread overview]
Message-ID: <1328114266.5355.44.camel@lenny> (raw)
In-Reply-To: <20120201151918.GC16714@quack.suse.cz>
On Wed, 2012-02-01 at 16:19 +0100, Jan Kara wrote:
> I've raised the issue with our GCC guys and they said to me that: "C does
> not provide such guarantee, nor can you reliably lock different
> structure fields with different locks if they share naturally aligned
> word-size memory regions. The C++11 memory model would guarantee this,
> but that's not implemented nor do you build the kernel with a C++11
> compiler."
That's interesting. So it seems like there are two solutions:
1) Use the same lock for a given bitfield
2) Split up the bitfield into different words
next prev parent reply other threads:[~2012-02-01 16:37 UTC|newest]
Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 15:19 Memory corruption due to word sharing Jan Kara
2012-02-01 15:19 ` Jan Kara
2012-02-01 15:34 ` Markus Trippelsdorf
2012-02-01 15:34 ` Markus Trippelsdorf
2012-02-01 16:37 ` Colin Walters [this message]
2012-02-01 16:37 ` Colin Walters
2012-02-01 16:56 ` Linus Torvalds
2012-02-01 16:56 ` Linus Torvalds
2012-02-01 17:11 ` Jiri Kosina
2012-02-01 17:11 ` Jiri Kosina
2012-02-01 17:37 ` Linus Torvalds
2012-02-01 17:37 ` Linus Torvalds
2012-02-01 17:41 ` Michael Matz
2012-02-01 17:41 ` Michael Matz
2012-02-01 18:09 ` David Miller
2012-02-01 18:09 ` David Miller
2012-02-01 18:45 ` Jeff Law
2012-02-01 18:45 ` Jeff Law
2012-02-01 19:09 ` Linus Torvalds
2012-02-01 19:09 ` Linus Torvalds
2012-02-02 15:51 ` Jeff Garzik
2012-02-02 15:51 ` Jeff Garzik
2012-02-01 18:57 ` Linus Torvalds
2012-02-01 18:57 ` Linus Torvalds
2012-02-01 19:04 ` Peter Bergner
2012-02-01 19:04 ` Peter Bergner
2012-02-01 18:52 ` Linus Torvalds
2012-02-01 18:52 ` Linus Torvalds
2012-02-02 9:35 ` Richard Guenther
2012-02-02 9:35 ` Richard Guenther
2012-02-02 9:37 ` Richard Guenther
2012-02-02 9:37 ` Richard Guenther
2012-02-02 13:43 ` Michael Matz
2012-02-02 13:43 ` Michael Matz
2012-02-01 16:41 ` Linus Torvalds
2012-02-01 16:41 ` Linus Torvalds
2012-02-01 17:42 ` Torvald Riegel
2012-02-01 17:42 ` Torvald Riegel
2012-02-01 19:40 ` Jakub Jelinek
2012-02-01 19:40 ` Jakub Jelinek
2012-02-01 20:01 ` Linus Torvalds
2012-02-01 20:01 ` Linus Torvalds
2012-02-01 20:16 ` Jakub Jelinek
2012-02-01 20:16 ` Jakub Jelinek
2012-02-01 20:44 ` Linus Torvalds
2012-02-01 20:44 ` Linus Torvalds
2012-02-02 15:58 ` Aldy Hernandez
2012-02-02 15:58 ` Aldy Hernandez
2012-02-02 16:28 ` Michael Matz
2012-02-02 16:28 ` Michael Matz
2012-02-02 17:51 ` Linus Torvalds
2012-02-02 17:51 ` Linus Torvalds
2012-02-01 20:19 ` Linus Torvalds
2012-02-01 20:19 ` Linus Torvalds
2012-02-02 9:46 ` Richard Guenther
2012-02-02 9:46 ` Richard Guenther
2012-02-01 19:44 ` Boehm, Hans
2012-02-01 19:44 ` Boehm, Hans
2012-02-01 19:54 ` Jeff Law
2012-02-01 19:54 ` Jeff Law
2012-02-01 19:47 ` Linus Torvalds
2012-02-01 19:47 ` Linus Torvalds
2012-02-01 19:58 ` Alan Cox
2012-02-01 19:58 ` Alan Cox
2012-02-01 20:41 ` Torvald Riegel
2012-02-01 20:41 ` Torvald Riegel
2012-02-01 20:59 ` Linus Torvalds
2012-02-01 20:59 ` Linus Torvalds
2012-02-01 21:24 ` Torvald Riegel
2012-02-01 21:24 ` Torvald Riegel
2012-02-01 21:55 ` Linus Torvalds
2012-02-01 21:55 ` Linus Torvalds
2012-02-01 21:25 ` Boehm, Hans
2012-02-01 21:25 ` Boehm, Hans
2012-02-01 22:27 ` Linus Torvalds
2012-02-01 22:27 ` Linus Torvalds
2012-02-01 22:45 ` Paul E. McKenney
2012-02-01 22:45 ` Paul E. McKenney
2012-02-01 23:11 ` Linus Torvalds
2012-02-01 23:11 ` Linus Torvalds
2012-02-02 18:42 ` Paul E. McKenney
2012-02-02 18:42 ` Paul E. McKenney
2012-02-02 19:08 ` Linus Torvalds
2012-02-02 19:08 ` Linus Torvalds
2012-02-02 19:37 ` Paul E. McKenney
2012-02-02 19:37 ` Paul E. McKenney
2012-02-03 16:38 ` Andrew MacLeod
2012-02-03 16:38 ` Andrew MacLeod
2012-02-03 17:16 ` Linus Torvalds
2012-02-03 17:16 ` Linus Torvalds
2012-02-03 19:16 ` Andrew MacLeod
2012-02-03 19:16 ` Andrew MacLeod
2012-02-03 20:00 ` Linus Torvalds
2012-02-03 20:00 ` Linus Torvalds
2012-02-03 20:19 ` Paul E. McKenney
2012-02-03 20:19 ` Paul E. McKenney
2012-02-06 15:38 ` Torvald Riegel
2012-02-06 15:38 ` Torvald Riegel
2012-02-10 19:27 ` Richard Henderson
2012-02-10 19:27 ` Richard Henderson
2012-02-02 11:19 ` Ingo Molnar
2012-02-02 11:19 ` Ingo Molnar
2012-02-01 21:04 ` Boehm, Hans
2012-02-01 21:04 ` Boehm, Hans
2012-02-02 9:28 ` Bernd Petrovitsch
2012-02-02 9:28 ` Bernd Petrovitsch
2012-02-01 17:08 ` Torvald Riegel
2012-02-01 17:08 ` Torvald Riegel
2012-02-01 17:29 ` Linus Torvalds
2012-02-01 17:29 ` Linus Torvalds
2012-02-01 20:53 ` Torvald Riegel
2012-02-01 20:53 ` Torvald Riegel
2012-02-01 21:20 ` Linus Torvalds
2012-02-01 21:20 ` Linus Torvalds
2012-02-01 21:37 ` Torvald Riegel
2012-02-01 21:37 ` Torvald Riegel
2012-02-01 22:18 ` Boehm, Hans
2012-02-01 22:18 ` Boehm, Hans
2012-02-01 17:52 ` Dennis Clarke
2012-02-01 17:52 ` Dennis Clarke
2012-02-02 11:11 ` James Courtier-Dutton
2012-02-02 11:11 ` James Courtier-Dutton
2012-02-02 11:24 ` Richard Guenther
2012-02-02 11:24 ` Richard Guenther
2012-02-02 11:13 ` David Sterba
2012-02-02 11:13 ` David Sterba
2012-02-02 11:23 ` Richard Guenther
2012-02-02 11:23 ` Richard Guenther
2012-02-03 6:45 ` DJ Delorie
2012-02-03 6:45 ` DJ Delorie
2012-02-03 9:37 ` Richard Guenther
2012-02-03 9:37 ` Richard Guenther
2012-02-03 10:03 ` Matthew Gretton-Dann
2012-02-03 10:03 ` Matthew Gretton-Dann
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