mm: replace get_user_pages_remote() write/force parameters with gup_flags
This removes the 'write' and 'force' from get_user_pages_remote() and
replaces them with 'gup_flags' 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: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/gup.c b/mm/gup.c
index bbc2e76..7aa113c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -915,9 +915,7 @@
* @mm: mm_struct of target mm
* @start: starting user address
* @nr_pages: number of pages from start to pin
- * @write: whether pages will be written to by the caller
- * @force: whether to force access even when user mapping is currently
- * protected (but never forces write access to shared mapping).
+ * @gup_flags: flags modifying lookup behaviour
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_pages long. Or NULL, if caller
* only intends to ensure the pages are faulted in.
@@ -946,9 +944,9 @@
* or similar operation cannot guarantee anything stronger anyway because
* locks can't be held over the syscall boundary.
*
- * If write=0, the page must not be written to. If the page is written to,
- * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
- * after the page is finished with, and before put_page is called.
+ * If gup_flags & FOLL_WRITE == 0, the page must not be written to. If the page
+ * is written to, set_page_dirty (or set_page_dirty_lock, as appropriate) must
+ * be called after the page is finished with, and before put_page is called.
*
* get_user_pages is typically used for fewer-copy IO operations, to get a
* handle on the memory by some means other than accesses via the user virtual
@@ -965,18 +963,12 @@
*/
long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
- int write, int force, struct page **pages,
+ unsigned int gup_flags, struct page **pages,
struct vm_area_struct **vmas)
{
- unsigned int flags = FOLL_TOUCH | FOLL_REMOTE;
-
- if (write)
- flags |= FOLL_WRITE;
- if (force)
- flags |= FOLL_FORCE;
-
return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
- NULL, false, flags);
+ NULL, false,
+ gup_flags | FOLL_TOUCH | FOLL_REMOTE);
}
EXPORT_SYMBOL(get_user_pages_remote);