On Wed, May 25, 2022 at 02:50:56PM -0700, Andrew Morton wrote: > On Thu, 26 May 2022 05:35:20 +0800 kernel test robot <lkp@xxxxxxxxx> wrote: > > > tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > > branch HEAD: 8cb8311e95e3bb58bd84d6350365f14a718faa6d Add linux-next specific files for 20220525 > > > > Error/Warning reports: > > > > ... > > > > Unverified Error/Warning (likely false positive, please contact us if interested): > > Could be so. > > > mm/shmem.c:1948 shmem_getpage_gfp() warn: should '(((1) << 12) / 512) << folio_order(folio)' be a 64 bit type? > > I've been seeing this one for a while. And from this report I can't > figure out what tool emitted it. Clang? This is a Smatch warning. I normally look over Smatch warnings before forwarding kbuild-bot emails but this email is a grab bag of static checker warnings from different tools. This warning has a high rate of false positives so I'm going to disable it by default. > > > > > ... > > > > |-- i386-randconfig-m021 > > | `-- mm-shmem.c-shmem_getpage_gfp()-warn:should-((()-)-)-folio_order(folio)-be-a-bit-type > > If you're going to use randconfig then shouldn't you make the config > available? Or maybe quote the KCONFIG_SEED - presumably there's a way > for others to regenerate. > > Anyway, the warning seems wrong to me. > > > #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT) > > #define BLOCKS_PER_PAGE (PAGE_SIZE/512) > > inode->i_blocks += BLOCKS_PER_PAGE << folio_order(folio); > > so the RHS here should have unsigned long type. Being able to generate > the cpp output would be helpful. That requires the .config. The heuristic is that "inode->i_blocks" is a u64 but this .config must be for a 32bit CPU. I'm just going to turn off all these warnings until I can figure out a better heuristic. regards, dan carpenter
