[PATCH 20/20] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails

[Christoph Hellwig]

Allow the callers to distinguish a real unmapped address vs a range
that can't be probed.

Suggested-by: Masami Hiramatsu <mhira...@kernel.org>
Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 mm/maccess.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/maccess.c b/mm/maccess.c
index 1e7d77656c596..4010d64189d21 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -25,7 +25,7 @@ bool __weak copy_from_kernel_nofault_allowed(void *dst, const 
void *unsafe_src,
 long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
 {
        if (!copy_from_kernel_nofault_allowed(dst, src, size))
-               return -EFAULT;
+               return -ERANGE;
 
        pagefault_disable();
        copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
@@ -69,7 +69,7 @@ long strncpy_from_kernel_nofault(char *dst, const void 
*unsafe_addr, long count)
        if (unlikely(count <= 0))
                return 0;
        if (!copy_from_kernel_nofault_allowed(dst, unsafe_addr, count))
-               return -EFAULT;
+               return -ERANGE;
 
        pagefault_disable();
        do {
@@ -107,7 +107,7 @@ long copy_from_kernel_nofault(void *dst, const void *src, 
size_t size)
        mm_segment_t old_fs = get_fs();
 
        if (!copy_from_kernel_nofault_allowed(dst, src, size))
-               return -EFAULT;
+               return -ERANGE;
 
        set_fs(KERNEL_DS);
        pagefault_disable();
@@ -174,7 +174,7 @@ long strncpy_from_kernel_nofault(char *dst, const void 
*unsafe_addr, long count)
        if (unlikely(count <= 0))
                return 0;
        if (!copy_from_kernel_nofault_allowed(dst, unsafe_addr, count))
-               return -EFAULT;
+               return -ERANGE;
 
        set_fs(KERNEL_DS);
        pagefault_disable();
-- 
2.26.2