[PATCH] mm/gfp: cast GFP_ZONE_TABLE entries to long to avoid shift overflow
From: Yankai Xu
Date: Thu Dec 11 2025 - 05:26:46 EST
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. This happens
because enum zone_type 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@xxxxxx>
---
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