commit 768ae309a96103ed02eb1e111e838c87854d8b51
author Lorenzo Stoakes <lstoakes@gmail.com> Thu Oct 13 01:20:16 2016 +0100
committer Linus Torvalds <torvalds@linux-foundation.org> Wed Oct 19 08:11:43 2016 -0700
tree 59f9070c68cc87d37e5edf6439b5074a96f5d3dd
parent 7f23b3504a0df63b724180262c5f3f117f21bcae

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

This removes the 'write' and 'force' from get_user_pages() 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: Christian König <christian.koenig@amd.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/gup.c

diff --git a/mm/gup.c b/mm/gup.c
index 3cfb55e..bbc2e76 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -987,18 +987,12 @@ EXPORT_SYMBOL(get_user_pages_remote);
  * obviously don't pass FOLL_REMOTE in here.
  */
 long get_user_pages(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;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
 	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       pages, vmas, NULL, false, flags);
+				       pages, vmas, NULL, false,
+				       gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages);
 

mm/mempolicy.c

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index ad1c96a..0b859af 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -850,7 +850,7 @@ static int lookup_node(unsigned long addr)
 	struct page *p;
 	int err;
 
-	err = get_user_pages(addr & PAGE_MASK, 1, 0, 0, &p, NULL);
+	err = get_user_pages(addr & PAGE_MASK, 1, 0, &p, NULL);
 	if (err >= 0) {
 		err = page_to_nid(p);
 		put_page(p);

mm/nommu.c

diff --git a/mm/nommu.c b/mm/nommu.c
index 842cfdd..70cb844 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -160,18 +160,11 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
  * - don't permit access to VMAs that don't support it, such as I/O mappings
  */
 long get_user_pages(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)
 {
-	int flags = 0;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
-	return __get_user_pages(current, current->mm, start, nr_pages, flags,
-				pages, vmas, NULL);
+	return __get_user_pages(current, current->mm, start, nr_pages,
+				gup_flags, pages, vmas, NULL);
 }
 EXPORT_SYMBOL(get_user_pages);
 
@@ -179,10 +172,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_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);
+	return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
 }
 EXPORT_SYMBOL(get_user_pages_locked);