mm: replace access_remote_vm() write parameter with gup_flags

This removes the 'write' argument from access_remote_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 8 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 79ebed3a4c2b..bac2d994850e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3935,19 +3935,14 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
  * @addr:       start address to access
  * @buf:        source or destination buffer
  * @len:        number of bytes to transfer
- * @write:      whether the access is a write
+ * @gup_flags:  flags modifying lookup behaviour
  *
  * The caller must hold a reference on @mm.
  */
 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
-                void *buf, int len, int write)
+                void *buf, int len, unsigned int gup_flags)
 {
-        unsigned int flags = FOLL_FORCE;
-
-        if (write)
-                flags |= FOLL_WRITE;
-
-        return __access_remote_vm(NULL, mm, addr, buf, len, flags);
+        return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
 }
 
 /*