On Wed, 2020-03-11 at 15:09 -0700, Roman Gushchin wrote: > +#ifdef CONFIG_CMA > +static unsigned long hugetlb_cma_size __initdata; > + > +static int __init cmdline_parse_hugetlb_cma(char *p) > +{ > + unsigned long long val; > + char *endptr; > + > + if (!p) > + return -EINVAL; > + > + val = simple_strtoull(p, &endptr, 0); > + hugetlb_cma_size = memparse(p, &p); > + return 0; > +} > + Here will generate a compilation warning, mm/hugetlb.c: In function 'cmdline_parse_hugetlb_cma': mm/hugetlb.c:5548:21: warning: variable 'val' set but not used [-Wunused-but- set-variable] unsigned long long val; ^~~ Also, the comments for simple_strtoull() in lib/vsprintf.c said, "This function is obsolete. Please use kstrtoull instead."