releases/2.6.32.12/lockdep-fix-incorrect-percpu-usage.patch

From mathieu.desnoyers@efficios.com  Wed Apr 21 15:39:34 2010
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 20 Apr 2010 10:33:50 -0400
Subject: lockdep: fix incorrect percpu usage
To: Greg KH <greg@kroah.com>
Cc: Tejun Heo <tj@kernel.org>, Randy Dunlap <randy.dunlap@oracle.com>, Greg Kroah-Hartman <gregkh@suse.de>, Peter Zijlstra <peterz@infradead.org>, stable <stable@kernel.org>, Rusty Russell <rusty@rustcorp.com.au>, linux-kernel@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>, Eric Dumazet <dada1@cosmosbay.com>, Ingo Molnar <mingo@elte.hu>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>
Message-ID: <20100420143350.GA14622@Krystal>
Content-Disposition: inline

From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

The mainline kernel as of 2.6.34-rc5 is not affected by this problem because
commit 10fad5e46f6c7bdfb01b1a012380a38e3c6ab346 fixed it by refactoring.

lockdep fix incorrect percpu usage

Should use per_cpu_ptr() to obfuscate the per cpu pointers (RELOC_HIDE is needed
for per cpu pointers).

git blame points to commit:

lockdep.c: commit 8e18257d29238311e82085152741f0c3aa18b74d

But it's really just moving the code around. But it's enough to say that the
problems appeared before Jul 19 01:48:54 2007, which brings us back to 2.6.23.

It should be applied to stable 2.6.23.x to 2.6.33.x (or whichever of these
stable branches are still maintained).

(tested on 2.6.33.1 x86_64)

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Randy Dunlap <randy.dunlap@oracle.com>
CC: Eric Dumazet <dada1@cosmosbay.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Tejun Heo <tj@kernel.org>
CC: Ingo Molnar <mingo@elte.hu>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Greg Kroah-Hartman <gregkh@suse.de>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 kernel/lockdep.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -591,9 +591,9 @@ static int static_obj(void *obj)
 	 * percpu var?
 	 */
 	for_each_possible_cpu(i) {
-		start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
-		end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
-					+ per_cpu_offset(i);
+		start = (unsigned long) per_cpu_ptr(&__per_cpu_start, i);
+		end   = (unsigned long) per_cpu_ptr(&__per_cpu_start, i)
+					+ PERCPU_ENOUGH_ROOM;
 
 		if ((addr >= start) && (addr < end))
 			return 1;