Commit 1cf3eb2f authored Jan 27, 2009 by Jeff Mahoney Committed by Pekka Enberg Jan 27, 2009

kmalloc: return NULL instead of link failure



The SLAB kmalloc with a constant value isn't consistent with the other
implementations because it bails out with __you_cannot_kmalloc_that_much
rather than returning NULL and properly allowing the caller to fall back
to vmalloc or take other action.  This doesn't happen with a non-constant
value or with SLOB or SLUB.

Starting with 2.6.28, I've been seeing build failures on s390x.  This is
due to init_section_page_cgroup trying to allocate 2.5MB when the max size
for a kmalloc on s390x is 2MB.

It's failing because the value is constant.  The workarounds at the call
size are ugly and the caller shouldn't have to change behavior depending
on what the backend of the API is.

So, this patch eliminates the link failure and returns NULL like the other
implementations.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: <stable@kernel.org>		[2.6.28.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

parent a6525042

include/linux/slab_def.h

+2 −8

Original line number	Diff line number	Diff line
		@@ -43,10 +43,7 @@ static inline void *kmalloc(size_t size, gfp_t flags)
		i++;
		#include <linux/kmalloc_sizes.h>
		#undef CACHE
		{
		extern void __you_cannot_kmalloc_that_much(void);
		__you_cannot_kmalloc_that_much();
		}
		return NULL;
		found:
		#ifdef CONFIG_ZONE_DMA
		if (flags & GFP_DMA)
		@@ -77,10 +74,7 @@ static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
		i++;
		#include <linux/kmalloc_sizes.h>
		#undef CACHE
		{
		extern void __you_cannot_kmalloc_that_much(void);
		__you_cannot_kmalloc_that_much();
		}
		return NULL;
		found:
		#ifdef CONFIG_ZONE_DMA
		if (flags & GFP_DMA)

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