[kbuild-all] Re: [linux-next:master 10679/10701] arch/x86/mm/pgtable.c:427:2: warning: variable length array 'u_pmds' is used

On Thu, 21 May 2020 03:56:53 +0800 kbuild test robot <lkp(a)intel.com&gt; wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > head: fb57b1fabcb28f358901b2df90abd2b48abc1ca8 > commit: 0e19fc1c40bd7516d5a30a459db4f49d48910847 [10679/10701] mm: consolidate pgd_index() and pgd_offset{_k}() definitions > config: i386-randconfig-a005-20200520 (attached as .config) > compiler: gcc-4.9 (Ubuntu 4.9.3-13ubuntu2) 4.9.3 > reproduce: > git checkout 0e19fc1c40bd7516d5a30a459db4f49d48910847 > # save the attached .config to linux build tree > make ARCH=i386 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kbuild test robot <lkp(a)intel.com&gt; > > All warnings (new ones prefixed by >>, old ones prefixed by <<): > > arch/x86/mm/pgtable.c: In function 'pgd_alloc': >>> arch/x86/mm/pgtable.c:427:2: warning: variable length array 'u_pmds' is used [-Wvla] > pmd_t *u_pmds[MAX_PREALLOCATED_USER_PMDS]; > ^ >>> arch/x86/mm/pgtable.c:428:2: warning: variable length array 'pmds' is used [-Wvla] > pmd_t *pmds[MAX_PREALLOCATED_PMDS]; > ^ Thanks. This works for me - perhaps Mike can come up with something smarter.

--- a/include/linux/pgtable.h~mm-consolidate-pgd_index-and-pgd_offset_k-definitions-fix +++ a/include/linux/pgtable.h @@ -62,11 +62,8 @@ static inline unsigned long pud_index(un #endif #ifndef pgd_index -static inline unsigned long pgd_index(unsigned long address) -{ - return ((address >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1)); -} -#define pgd_index pgd_index +/* Must be a compile-time constant, so implement it as a macro */ +#define pgd_index(a) (((a) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1)) #endif #ifndef pte_offset_kernel _