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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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vineet Gupta 2013-04-29 15:06:15 -07:00 committed by Linus Torvalds
parent 369a713e96
commit 94f3d3afb6
1 changed files with 3 additions and 0 deletions
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3
mm/memblock.c
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@ -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);