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@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
mm/memblock.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/mm/memblock.c b/mm/memblock.c
index 1bcd9b9..8080cf8 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -821,6 +821,9 @@ 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);
--
1.7.4.1
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