linux-kernel - Re: [linux-next-20130422] Bug in SLAB?

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Message-ID: <0000013e6705da99-094923c6-e239-43d2-8f0c-5e661656a27c-000000@email.amazonses.com>
Date:	Thu, 2 May 2013 20:53:57 +0000
From:	Christoph Lameter <cl@...ux.com>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
cc:	glommer@...allels.com, penberg@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [linux-next-20130422] Bug in SLAB?

On Wed, 1 May 2013, Tetsuo Handa wrote:

> The culprit location is possibly in SLAB because the kernel boots if built with
> CONFIG_DEBUG_SLAB=n || CONFIG_DEBUG_SPINLOCK=n || CONFIG_DEBUG_PAGEALLOC=n.

I have booted such a configuration just fine. Please have a look at the
kernel config that I send or send me yours.

Here is a patch that restores the old behavior for SLAB



Subject: slab: Return NULL for oversized allocations

The inline path seems to have changed the SLAB behavior for very large
kmalloc allocations. This patch restores the old behavior.

Signed-off-by: Christoph Lameter <cl@...ux.com>


Index: linux/include/linux/slab_def.h
===================================================================
--- linux.orig/include/linux/slab_def.h	2013-05-02 15:02:45.864728115 -0500
+++ linux/include/linux/slab_def.h	2013-05-02 15:06:14.940474110 -0500
@@ -126,6 +126,9 @@ static __always_inline void *kmalloc(siz
 		if (!size)
 			return ZERO_SIZE_PTR;

+		if (size >= KMALLOC_MAX_SIZE)
+			return NULL;
+
 		i = kmalloc_index(size);

 #ifdef CONFIG_ZONE_DMA
@@ -172,6 +175,9 @@ static __always_inline void *kmalloc_nod
 		if (!size)
 			return ZERO_SIZE_PTR;

+		if (size > KMALLOC_MAX_SIZE)
+			return NULL;
+
 		i = kmalloc_index(size);

 #ifdef CONFIG_ZONE_DMA
--
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