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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>