mm: replace get_user_pages_locked() write/force parameters with gup_flags

commit 3b913179c3fa89dd0e304193fa0c746fc0481447 upstream.

This removes the 'write' and 'force' use from get_user_pages_locked()
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>
[bwh: Backported to 4.4: adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c043c936a4a526a725f22be3a171fbc94c5d4a37..cbb9bd8b910ae1da9ef836d9b82a716fbb31b452 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1203,8 +1203,7 @@ long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                    struct vm_area_struct **vmas);
 long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
                    unsigned long start, unsigned long nr_pages,
-                   int write, int force, struct page **pages,
-                   int *locked);
+                   unsigned int gup_flags, struct page **pages, int *locked);
 long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
                               unsigned long start, unsigned long nr_pages,
                               struct page **pages, unsigned int gup_flags);

diff --git a/mm/frame_vector.c b/mm/frame_vector.c
index 7cf2b7163222b1d304ba1a4dde0604c5f29a3bbd..40e3116b5666a13030574631594737da4ff5bcda 100644 (file)
--- a/mm/frame_vector.c
+++ b/mm/frame_vector.c
@@ -41,10 +41,16 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
        int ret = 0;
        int err;
        int locked;
+       unsigned int gup_flags = 0;
 
        if (nr_frames == 0)
                return 0;
 
+       if (write)
+               gup_flags |= FOLL_WRITE;
+       if (force)
+               gup_flags |= FOLL_FORCE;
+
        if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
                nr_frames = vec->nr_allocated;
 
@@ -59,7 +65,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
                vec->got_ref = true;
                vec->is_pfns = false;
                ret = get_user_pages_locked(current, mm, start, nr_frames,
-                       write, force, (struct page **)(vec->ptrs), &locked);
+                       gup_flags, (struct page **)(vec->ptrs), &locked);
                goto out;
        }
 

diff --git a/mm/gup.c b/mm/gup.c
index 6bbec1b694eab7e89f3e2ae14c49eb4d53d975d4..bcdefb9772690296e83604266581754be2eccf7d 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -737,18 +737,12 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
  */
 long get_user_pages_locked(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,
                           int *locked)
 {
-       unsigned int flags = FOLL_TOUCH;
-
-       if (write)
-               flags |= FOLL_WRITE;
-       if (force)
-               flags |= FOLL_FORCE;
-
        return __get_user_pages_locked(tsk, mm, start, nr_pages,
-                                      pages, NULL, locked, true, flags);
+                                      pages, NULL, locked, true,
+                                      gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 

diff --git a/mm/nommu.c b/mm/nommu.c
index e249e06579fb1956e3471809ab140fb836fc9f21..6cbb985238c49b178b00180148b4fe0abfc1c496 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -201,9 +201,12 @@ EXPORT_SYMBOL(get_user_pages);
 
 long get_user_pages_locked(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,
                           int *locked)
 {
+       int write = gup_flags & FOLL_WRITE;
+       int force = gup_flags & FOLL_FORCE;
+
        return get_user_pages(tsk, mm, start, nr_pages, write, force,
                              pages, NULL);
 }