linux-kernel - [PATCH] kmemleak: Do not use off-slab management with SLAB

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Message-ID: <20091014153146.8955.19964.stgit@pc1117.cambridge.arm.com>
Date:	Wed, 14 Oct 2009 16:31:46 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	linux-kernel@...r.kernel.org
Cc:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Christoph Lameter <cl@...ux-foundation.org>
Subject: [PATCH] kmemleak: Do not use off-slab management with SLAB_NOLEAKTRACE

With the slab allocator, if off-slab management is enabled for the
kmem_caches used by kmemleak, it leads to recursive calls into
kmemleak_alloc(). Off-slab management can be triggered by other config
options increasing the slab size, e.g. DEBUG_PAGEALLOC.

Reported-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc: Pekka Enberg <penberg@...helsinki.fi>
Cc: Christoph Lameter <cl@...ux-foundation.org>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
---
 mm/slab.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 7dfa481..646db30 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2261,9 +2261,11 @@ kmem_cache_create (const char *name, size_t size, size_t align,
 	/*
 	 * Determine if the slab management is 'on' or 'off' slab.
 	 * (bootstrapping cannot cope with offslab caches so don't do
-	 * it too early on.)
+	 * it too early on. Always use on-slab management when
+	 * SLAB_NOLEAKTRACE to avoid recursive calls into kmemleak)
 	 */
-	if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init)
+	if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init &&
+	    !(flags & SLAB_NOLEAKTRACE))
 		/*
 		 * Size is large, assume best to place the slab management obj
 		 * off-slab (should allow better packing of objs).

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