When a new zone is added to enum zone_type in mmzone.h, the existing GFP_ZONE_TABLE macro causes a compile-time shift overflow: CC arch/x86/kernel/asm-offsets.s In file included from ./include/linux/slab.h:16, from ./include/linux/crypto.h:18, from arch/x86/kernel/asm-offsets.c:9: ./include/linux/gfp.h: In function ‘gfp_zone’: ./include/linux/gfp.h:132:27: error: left shift count >= width of type [-Werror=shift-count-overflow] 132 | | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\ | ^~ ./include/linux/gfp.h:157:14: note: in expansion of macro ‘GFP_ZONE_TABLE’ 157 | z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & | This can be reproduced by adding a new zone: @@ -868,6 +868,7 @@ enum zone_type { #ifdef CONFIG_ZONE_DEVICE ZONE_DEVICE, #endif + ZONE_FOO, __MAX_NR_ZONES }; This happens because the left-hand side operands of the shifts inside GFP_ZONE_TABLE are enum zone_type, which is of type int. The shift is logically valid because it has been checked by 16 * GFP_ZONES_SHIFT > BITS_PER_LONG previously. Fixed this by casting each value in GFP_ZONE_TABLE to type long. Signed-off-by: Yankai Xu <815559068@qq.com> --- v2: - Added compiler warning messages and reproduce steps --- include/linux/gfp.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index b155929af..e694f3103 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -122,14 +122,14 @@ static inline bool gfpflags_allow_spinning(const gfp_t gfp_flags) #endif #define GFP_ZONE_TABLE ( \ - (ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA32 << ___GFP_DMA32 * GFP_ZONES_SHIFT) \ - | (ZONE_NORMAL << ___GFP_MOVABLE * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT) \ - | (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)\ - | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\ + ((long)ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \ + | ((long)OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT) \ + | ((long)OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * GFP_ZONES_SHIFT) \ + | ((long)OPT_ZONE_DMA32 << ___GFP_DMA32 * GFP_ZONES_SHIFT) \ + | ((long)ZONE_NORMAL << ___GFP_MOVABLE * GFP_ZONES_SHIFT) \ + | ((long)OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT) \ + | ((long)ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)\ + | ((long)OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\ ) /* -- 2.43.0