Re: [PATCH v3 1/2] memblock: add assertion for zero allocation alignment

[Vineet Gupta]

Hi Andrew,

On Friday 22 February 2013 02:23 AM, Tejun Heo wrote:
> On Thu, Feb 21, 2013 at 12:52 PM, Vineet Gupta
> <Vineet.Gupta1@xxxxxxxxxxxx> wrote:
>> 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
> 
> Acked-by: Tejun Heo <tj@xxxxxxxxxx>
> 
> Thanks.
> 

I'm hoping this will be routed via the mm tree.

Thx,
-Vineet
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