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@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/xtensa/include/uapi/asm/mman.h b/arch/xtensa/include/uapi/asm/mman.h
index be72606..ebbb488 100644 (file)
--- a/arch/xtensa/include/uapi/asm/mman.h
+++ b/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

diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
index abd238d..cb556b4 100644 (file)
--- a/include/uapi/asm-generic/mman-common.h
+++ b/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
  */

diff --git a/mm/nommu.c b/mm/nommu.c
index eb3e2e5..fed1b6e 100644 (file)
--- a/mm/nommu.c
+++ b/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);