[PATCH 3/3] x86: Let extend_brk return a NULL pointer instead of just BUG_ON.

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

The callers of this function (dmi_alloc) and the various
Xen related ones can deal with a NULL pointer.

Suggested-by: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/x86/kernel/setup.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 16be6dc..13d6c51 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -268,9 +268,10 @@ void * __init extend_brk(size_t size, size_t align)
 	BUG_ON(_brk_start == 0);
 	BUG_ON(align & mask);
 
-	_brk_end = (_brk_end + mask) & ~mask;
-	BUG_ON((char *)(_brk_end + size) > __brk_limit);
+	if ((char *)(((_brk_end + mask) & ~mask) + size) > __brk_limit)
+		return NULL;
 
+	_brk_end = (_brk_end + mask) & ~mask;
 	ret = (void *)_brk_end;
 	_brk_end += size;
 
-- 
1.7.7.6