[patch 11/33] kmalloc: return NULL instead of link failure

[Greg KH]

2.6.28-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Jeff Mahoney <jeffm@xxxxxxxx>

commit 1cf3eb2ff6b0844c678f2f48d0053b9d12b7da67 upstream.

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@xxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 include/linux/slab_def.h |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -43,10 +43,7 @@ static inline void *kmalloc(size_t size,
 			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 
 			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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