From: Arnd Bergmann <arnd@xxxxxxxx> Subject: page flags: prioritize kasan bits over last-cpuid 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. [arnd@xxxxxxxx: build fix] Link: http://lkml.kernel.org/r/CAK8P3a3Mno1SWTcuAOT0Wa9VS15pdU6EfnkxLbDpyS55yO04+g@xxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/20190722115520.3743282-1-arnd@xxxxxxxx Link: https://lore.kernel.org/lkml/20190618095347.3850490-1-arnd@xxxxxxxx/ Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc") Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/mips/vdso/vdso.h | 1 + include/linux/page-flags-layout.h | 18 +++++++++++------- 2 files changed, 12 insertions(+), 7 deletions(-) --- a/arch/mips/vdso/vdso.h~page-flags-prioritize-kasan-bits-over-last-cpuid +++ a/arch/mips/vdso/vdso.h @@ -9,6 +9,7 @@ #if _MIPS_SIM != _MIPS_SIM_ABI64 && defined(CONFIG_64BIT) /* Building 32-bit VDSO for the 64-bit kernel. Fake a 32-bit Kconfig. */ +#define BUILD_VDSO32_64 #undef CONFIG_64BIT #define CONFIG_32BIT 1 #ifndef __ASSEMBLY__ --- a/include/linux/page-flags-layout.h~page-flags-prioritize-kasan-bits-over-last-cpuid +++ a/include/linux/page-flags-layout.h @@ -32,6 +32,7 @@ #endif /* CONFIG_SPARSEMEM */ +#ifndef BUILD_VDSO32_64 /* * page->flags layout: * @@ -76,20 +77,22 @@ #define LAST_CPUPID_SHIFT 0 #endif -#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS +#ifdef CONFIG_KASAN_SW_TAGS +#define KASAN_TAG_WIDTH 8 +#else +#define KASAN_TAG_WIDTH 0 +#endif + +#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT+KASAN_TAG_WIDTH \ + <= BITS_PER_LONG - NR_PAGEFLAGS #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT #else #define LAST_CPUPID_WIDTH 0 #endif -#ifdef CONFIG_KASAN_SW_TAGS -#define KASAN_TAG_WIDTH 8 #if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH+LAST_CPUPID_WIDTH+KASAN_TAG_WIDTH \ > BITS_PER_LONG - NR_PAGEFLAGS -#error "KASAN: not enough bits in page flags for tag" -#endif -#else -#define KASAN_TAG_WIDTH 0 +#error "Not enough bits in page flags" #endif /* @@ -104,4 +107,5 @@ #define LAST_CPUPID_NOT_IN_PAGE_FLAGS #endif +#endif #endif /* _LINUX_PAGE_FLAGS_LAYOUT */ _
