On 10/12/2016 05:54 PM, Michal Hocko wrote:
> On Wed 12-10-16 16:44:31, zijun_hu wrote:
>> On 10/12/2016 04:25 PM, Michal Hocko wrote:
>>> On Wed 12-10-16 15:24:33, zijun_hu wrote:
> [...]
>>>> i found the following code segments in mm/vmalloc.c
>>>> static struct vmap_area *alloc_vmap_area(unsigned long size,
>>>> unsigned long align,
>>>> unsigned long vstart, unsigned long vend,
>>>> int node, gfp_t gfp_mask)
>>>> {
>>>> ...
>>>>
>>>> BUG_ON(!size);
>>>> BUG_ON(offset_in_page(size));
>>>> BUG_ON(!is_power_of_2(align));
>>>
>>> See a recent Linus rant about BUG_ONs. These BUG_ONs are quite old and
>>> from a quick look they are even unnecessary. So rather than adding more
>>> of those, I think removing those that are not needed is much more
>>> preferred.
>>>
>> i notice that, and the above code segments is used to illustrate that
>> input parameter checking is necessary sometimes
>
> Why do you think it is necessary here?
>
i am sorry for reply late
i don't know whether it is necessary
i just find there are so many sanity checkup in current internal interfaces
