Messages in this thread | | | Subject | Re: [PATCH] [v3] page flags: prioritize kasan bits over last-cpuid | From | Andrey Ryabinin <> | Date | Mon, 22 Jul 2019 15:26:07 +0300 |
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On 7/22/19 2:55 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. > > Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc") > Link: https://lore.kernel.org/lkml/20190618095347.3850490-1-arnd@arndb.de/ > Reviewed-by: Andrey Konovalov <andreyknvl@google.com> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
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