On 2/17/22 11:44, Miaohe Lin wrote: > On 2022/2/17 17:23, Vlastimil Babka wrote: >> On 2/17/22 10:16, Miaohe Lin wrote: >>> Use helper function is_power_of_2() to check if KMALLOC_MIN_SIZE is power >>> of two. Minor readability improvement. >>> >>> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> >> >> We can try, but in case some compiler will no longer able to perform the >> check at build-time (although is_power_of_2() looks sufficiently trivial >> too), we'll have to revert it. > > I see. I checked the compiler in my env but there might be some compilers can't > perform the check at build-time. I'll add this to the slab tree and linux-next and we'll see if wider testing uncovers such compilers. Should be unlikely. > Many thanks for your reply. > >> >>> --- >>> mm/slab_common.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/mm/slab_common.c b/mm/slab_common.c >>> index 23f2ab0713b7..6ee64d6208b3 100644 >>> --- a/mm/slab_common.c >>> +++ b/mm/slab_common.c >>> @@ -807,7 +807,7 @@ void __init setup_kmalloc_cache_index_table(void) >>> unsigned int i; >>> >>> BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || >>> - (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1))); >>> + !is_power_of_2(KMALLOC_MIN_SIZE)); >>> >>> for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { >>> unsigned int elem = size_index_elem(i); >> >> . >> >