On 6/18/19 6:30 PM, Arnd Bergmann wrote: > On Tue, Jun 18, 2019 at 4:30 PM Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote: >> On 6/18/19 12:53 PM, Arnd Bergmann wrote: >>> ARM64 randdconfig builds regularly run into a build error, especially >>> when NUMA_BALANCING and SPARSEMEM are enabled but not SPARSEMEM_VMEMMAP: >>> >>> #error "KASAN: not enough bits in page flags for tag" >>> >>> The last-cpuid bits are already contitional on the available space, >>> so the result of the calculation is a bit random on whether they >>> were already left out or not. >>> >>> Adding the kasan tag bits before last-cpuid makes it much more likely >>> to end up with a successful build here, and should be reliable for >>> randconfig at least, as long as that does not randomize NR_CPUS >>> or NODES_SHIFT but uses the defaults. >>> >>> In order for the modified check to not trigger in the x86 vdso32 code >>> where all constants are wrong (building with -m32), enclose all the >>> definitions with an #ifdef. >>> >> >> Why not keep "#error "KASAN: not enough bits in page flags for tag"" under "#ifdef CONFIG_KASAN_SW_TAGS" ? > > I think I had meant the #error to leave out the mention of KASAN, as there > might be other reasons for using up all the bits, but then I did not change > it in the end. > > Should I remove the "KASAN" word or add the #ifdef when resending? It seems like changing the error message is a better choice. Don't forget to remove "for tag" as well.
