From: Christoph Hellwig <hch@xxxxxx> Subject: mm: fix the MAP_UNINITIALIZED flag We can't expose UAPI symbols differently based on CONFIG_ symbols, as userspace won't have them available. Instead always define the flag, but only respect it based on the config option. Link: http://lkml.kernel.org/r/20190703122359.18200-2-hch@xxxxxx Signed-off-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Vladimir Murzin <vladimir.murzin@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/xtensa/include/uapi/asm/mman.h | 6 +----- include/uapi/asm-generic/mman-common.h | 8 +++----- mm/nommu.c | 4 +++- 3 files changed, 7 insertions(+), 11 deletions(-) --- a/arch/xtensa/include/uapi/asm/mman.h~mm-fix-the-map_uninitialized-flag +++ a/arch/xtensa/include/uapi/asm/mman.h @@ -56,12 +56,8 @@ #define MAP_STACK 0x40000 /* give out an address that is best suited for process/thread stacks */ #define MAP_HUGETLB 0x80000 /* create a huge page mapping */ #define MAP_FIXED_NOREPLACE 0x100000 /* MAP_FIXED which doesn't unmap underlying mapping */ -#ifdef CONFIG_MMAP_ALLOW_UNINITIALIZED -# define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could be +#define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could be * uninitialized */ -#else -# define MAP_UNINITIALIZED 0x0 /* Don't support this flag */ -#endif /* * Flags for msync --- a/include/uapi/asm-generic/mman-common.h~mm-fix-the-map_uninitialized-flag +++ a/include/uapi/asm-generic/mman-common.h @@ -19,15 +19,13 @@ #define MAP_TYPE 0x0f /* Mask for type of mapping */ #define MAP_FIXED 0x10 /* Interpret addr exactly */ #define MAP_ANONYMOUS 0x20 /* don't use a file */ -#ifdef CONFIG_MMAP_ALLOW_UNINITIALIZED -# define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could be uninitialized */ -#else -# define MAP_UNINITIALIZED 0x0 /* Don't support this flag */ -#endif /* 0x0100 - 0x80000 flags are defined in asm-generic/mman.h */ #define MAP_FIXED_NOREPLACE 0x100000 /* MAP_FIXED which doesn't unmap underlying mapping */ +#define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could be + * uninitialized */ + /* * Flags for mlock */ --- a/mm/nommu.c~mm-fix-the-map_uninitialized-flag +++ a/mm/nommu.c @@ -1261,7 +1261,9 @@ unsigned long do_mmap(struct file *file, add_nommu_region(region); /* clear anonymous mappings that don't ask for uninitialized data */ - if (!vma->vm_file && !(flags & MAP_UNINITIALIZED)) + if (!vma->vm_file && + (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) || + !(flags & MAP_UNINITIALIZED))) memset((void *)region->vm_start, 0, region->vm_end - region->vm_start); _
