linux-kernel - [PATCH core/percpu] percpu: fix too low alignment restriction on UP

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Date:	Thu, 26 Feb 2009 11:03:34 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Yinghai Lu <yinghai@...nel.org>, rusty@...tcorp.com.au,
	tglx@...utronix.de, x86@...nel.org, linux-kernel@...r.kernel.org,
	hpa@...or.com, jeremy@...p.org, cpw@....com,
	nickpiggin@...oo.com.au, ink@...assic.park.msu.ru
Subject: [PATCH core/percpu] percpu: fix too low alignment restriction on
 UP

UP __alloc_percpu() triggered WARN_ON_ONCE() if the requested
alignment is larger than that of unsigned long long, which is too
small for all the cacheline aligned allocations.  Bump it up to
SMP_CACHE_BYTES which kmalloc allocations generally guarantee.

Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-by: Ingo Molnar <mingo@...e.hu>
---
Hello, Ingo.

I somehow completely forgot about testing UP.  Sorry about that. :-)
The following patch should do it.  Also available in the #tj-percpu
tree.

Thanks.

 include/linux/percpu.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index d8e5a9a..545b068 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -156,7 +156,7 @@ static inline void *__alloc_percpu(size_t size, size_t align)
 	 * on it.  Larger alignment should only be used for module
 	 * percpu sections on SMP for which this path isn't used.
 	 */
-	WARN_ON_ONCE(align > __alignof__(unsigned long long));
+	WARN_ON_ONCE(align > SMP_CACHE_BYTES);
 	return kzalloc(size, GFP_KERNEL);
 }
 
-- 
1.6.0.2

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