linux-kernel - [PATCH percpu/for-3.18] percpu: fix how @gfp is interpreted by the percpu allocator

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Message-ID: <20141008160823.GD8184@htj.dyndns.org>
Date:	Wed, 8 Oct 2014 12:08:23 -0400
From:	Tejun Heo <tj@...nel.org>
To:	linux-kernel@...r.kernel.org
Cc:	Christoph Lameter <cl@...ux-foundation.org>
Subject: [PATCH percpu/for-3.18] percpu: fix how @gfp is interpreted by the
 percpu allocator

>From 6ae833c7fe0c6ef1f0ab13cc775da230d6f4c256 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@...nel.org>
Date: Wed, 8 Oct 2014 12:01:52 -0400

When @gfp is specified, the percpu allocator is interested in whether
it contains all of GFP_KERNEL or not.  If it does, the normal
allocation path is taken; otherwise, the atomic allocation path.
Unfortunately, pcpu_alloc() was incorrectly testing for whether @gfp
contains any part of GFP_KERNEL.

Fix it by testing "(gfp & GFP_KERNEL) != GFP_KERNEL" instead of
"!(gfp & GFP_KERNEL)" to decide whether the allocation should be
atomic or not.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
Oops, noticed this while preparing the pull request for v3.18-rc1.
Applied to percpu/for-3.18.

Thanks.

 mm/percpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index e10f9f7..014bab6 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -876,7 +876,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
 	static int warn_limit = 10;
 	struct pcpu_chunk *chunk;
 	const char *err;
-	bool is_atomic = !(gfp & GFP_KERNEL);
+	bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
 	int occ_pages = 0;
 	int slot, off, new_alloc, cpu, ret;
 	unsigned long flags;
-- 
1.9.3

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