mm: remove write/force parameters from __get_user_pages_unlocked()

This removes the redundant 'write' and 'force' parameters from
__get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 07514d41ebcc..be8dc8d1edb9 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -88,12 +88,16 @@ static int process_vm_rw_single_vec(unsigned long addr,
         ssize_t rc = 0;
         unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
                 / sizeof(struct pages *);
+        unsigned int flags = FOLL_REMOTE;
 
         /* Work out address and page range required */
         if (len == 0)
                 return 0;
         nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
 
+        if (vm_write)
+                flags |= FOLL_WRITE;
+
         while (!rc && nr_pages && iov_iter_count(iter)) {
                 int pages = min(nr_pages, max_pages_per_loop);
                 size_t bytes;
@@ -104,8 +108,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
                  * current/current->mm
                  */
                 pages = __get_user_pages_unlocked(task, mm, pa, pages,
-                                                  vm_write, 0, process_pages,
-                                                  FOLL_REMOTE);
+                                                  process_pages, flags);
                 if (pages <= 0)
                         return -EFAULT;