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Message-ID: <Pine.LNX.4.64.0906111143490.6132@melkki.cs.Helsinki.FI>
Date: Thu, 11 Jun 2009 11:44:25 +0300 (EEST)
From: Pekka J Enberg <penberg@...helsinki.fi>
To: linux-kernel@...r.kernel.org
cc: cl@...ux-foundation.org, mel@....ul.ie, Larry.Finger@...inger.net
Subject: [PATCH 2/2] SLUB: Disable debugging if it increases the minimum page
order
From: Pekka Enberg <penberg@...helsinki.fi>
As CONFIG_SLUB_DEBUG is almost always enabled, we need to disable debugging on
per-cache basis if the added debug metadata increases minimum page order. This
is a problem for large caches such as kmalloc-4096 as seen in the following
bugzilla report:
http://bugzilla.kernel.org/show_bug.cgi?id=13319
Cc: Christoph Lameter <cl@...ux-foundation.org>
Cc: Larry Finger <Larry.Finger@...inger.net>
Cc: Mel Gorman <mel@....ul.ie>
Signed-off-by: Pekka Enberg <penberg@...helsinki.fi>
---
mm/slub.c | 13 +++++++++++++
1 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 2bbacfc..45080d3 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2385,6 +2385,16 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
}
+#define MAX_DEBUG_SIZE (3 * sizeof(void *) + 2 * sizeof(struct track))
+
+static bool must_disable_debug(size_t size)
+{
+ /*
+ * Disable debugging if it increases the minimum page order.
+ */
+ return get_order(size + MAX_DEBUG_SIZE) > get_order(size);
+}
+
static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags,
const char *name, size_t size,
size_t align, unsigned long flags,
@@ -2397,6 +2407,9 @@ static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags,
s->align = align;
s->flags = kmem_cache_flags(size, flags, name, ctor);
+ if (must_disable_debug(size))
+ s->flags &= ~(SLAB_POISON|SLAB_RED_ZONE|SLAB_STORE_USER);
+
if (!calculate_sizes(s, -1))
goto error;
--
1.6.0.4
--
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