From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Date: Sun, 10 Mar 2013 10:54:46 +0000 (+1100)
Subject: memblock: add assertion for zero allocation alignment
X-Git-Tag: next-20130312~3^2~229
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=479a91e1e683e55953429d361082c93f37052c2f;p=karo-tx-linux.git

memblock: add assertion for zero allocation alignment

This came to light when calling memblock allocator from arc port (for
copying flattended DT).  If a "0" alignment is passed, the allocator
round_up() call incorrectly rounds up the size to 0.

round_up(num, alignto) => ((num - 1) | (alignto -1)) + 1

While the obvious allocation failure causes kernel to panic, it is better
to warn the caller to fix the code.

Tejun suggested that instead of BUG_ON(!align) - which might be
ineffective due to pending console init and such, it is better to WARN_ON,
and continue the boot with a reasonable default align.

Caller passing @size need not be handled similarly as the subsequent
panic will indicate that anyhow.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/memblock.c b/mm/memblock.c
index b8d9147e5c08..2cce8b3e76ed 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -771,6 +771,9 @@ static phys_addr_t __init memblock_alloc_base_nid(phys_addr_t size,
 {
 	phys_addr_t found;
 
+	if (WARN_ON(!align))
+		align = __alignof__(long long);
+
 	/* align @size to avoid excessive fragmentation on reserved array */
 	size = round_up(size, align);