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

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>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index abd53f2..9fe9b04 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
                            int write, int force, struct page **pages,
                            struct vm_area_struct **vmas);
 long get_user_pages_locked(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 381bb07..81b6749 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(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 373d1ec..3cfb55e 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -848,18 +848,12 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
  *          up_read(&mm->mmap_sem);
  */
 long get_user_pages_locked(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(current, current->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 7e27add..842cfdd 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -176,9 +176,12 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 EXPORT_SYMBOL(get_user_pages);
 
 long get_user_pages_locked(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(start, nr_pages, write, force, pages, NULL);
 }
 EXPORT_SYMBOL(get_user_pages_locked);