On Mon, Mar 14, 2022 at 04:30:38PM +0300, Dan Carpenter wrote: > On Sun, Mar 13, 2022 at 04:06:37AM +0000, Matthew Wilcox wrote: > > On Sun, Mar 13, 2022 at 11:01:09AM +0800, kernel test robot wrote: > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > > > head: 71941773e143369a73c9c4a3b62fbb60736a1182 > > > commit: b786e44a4dbfe64476e7120ec7990b89a37be37d [9762/11953] mm: Convert page_vma_mapped_walk to work on PFNs > > > config: riscv-randconfig-m031-20220312 (https://download.01.org/0day-ci/archive/20220313/202203131056.WINF40Gt-lkp@xxxxxxxxx/config ) > > > compiler: riscv64-linux-gcc (GCC) 11.2.0 > > > > > > If you fix the issue, kindly add following tag as appropriate > > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > > > > smatch warnings: > > > mm/page_vma_mapped.c:246 page_vma_mapped_walk() warn: always true condition '(pvmw->nr_pages >= (1 << ( - (12)))) => (0-u64max >= 0)' > > > > Looks like a duplicate of https://lore.kernel.org/lkml/YgpzPru8aFA5sHOI@xxxxxxxxxxxxxxxxxxxx/ > > > > Dan, any thoughts? Do you consider this a false positive from smatch? > > > > That's really weird that HPAGE_PMD_NR ends up as zero... Does it wrap > to zero? It's actually weirder than that: #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; }) #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT) #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER) so it should be (1<<(0-12)) > Anyway, it would be easy to silence the warning based on that it's on an > impossible path but I think that's not the right idea. > > if (is_impossible_path()) > return; > > A lot of the bugs that Smatch finds are in impossible to reach error > handling code. I'll instead silence it based on that the macro > definition changes. Add it to smatch_data/kernel.unconstant_macros: > > > - if (!possibly_false_rl(rl_left, expr->op, rl_right)) { > + if (!possibly_false_rl(rl_left, expr->op, rl_right) && > + !is_unconstant_macro(expr->left) && > + !is_unconstant_macro(expr->right)) { > char *name = expr_to_str(expr); > > sm_warning("always true condition '(%s) => (%s %s %s)'", name, > > I'll test this out overnight, tonight. Thanks! I'd be happy to rearrange this code to avoid the smatch report, but it's not quite clear to me how I could/should do that.
