Re: [PATCH v2] mm/shmem.c: check the return value of mpol_to_str()

[KOSAKI Motohiro <kosaki.motohiro@gmail.com>]

(9/15/13 10:55 PM), Chen Gang wrote:
> On 09/14/2013 12:50 AM, KOSAKI Motohiro wrote:
>>> ---
>>>    mm/shmem.c |    2 +-
>>>    1 files changed, 1 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/mm/shmem.c b/mm/shmem.c
>>> index 8612a95..3f81120 100644
>>> --- a/mm/shmem.c
>>> +++ b/mm/shmem.c
>>> @@ -890,7 +890,7 @@ static void shmem_show_mpol(struct seq_file *seq,
>>> struct mempolicy *mpol)
>>>        if (!mpol || mpol->mode == MPOL_DEFAULT)
>>>            return;        /* show nothing */
>>>
>>> -    mpol_to_str(buffer, sizeof(buffer), mpol);
>>> +    VM_BUG_ON(mpol_to_str(buffer, sizeof(buffer), mpol) < 0);
>>
>> NAK. VM_BUG_ON is a kind of assertion. It erase the contents if
>> CONFIG_DEBUG_VM not set.
>> An argument of assertion should not have any side effect.
>
> Oh, really it is. In my opinion, need use "BUG_ON(mpol_to_str() < 0)"
> instead of "VM_BUG_ON(mpol_to_str() < 0);".

BUG_ON() is safe. but I still don't like it. As far as I heard, Google
changes BUG_ON as nop. So, BUG_ON(mpol_to_str() < 0) breaks google.
Please treat an assertion as assertion. Not any other something.


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