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

commit 768ae309a96103ed02eb1e111e838c87854d8b51 upstream.

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>
[bwh: Backported to 4.4:
 - Drop changes in rapidio, vchiq, goldfish
 - Keep the "write" variable in amdgpu_ttm_tt_pin_userptr() as it's still
   needed
 - Also update calls from various other places that now use
   get_user_pages_remote() upstream, which were updated there by commit
   9beae1ea8930 "mm: replace get_user_pages_remote() write/force ..."
 - Also update calls from hfi1 and ipath
 - Adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 15 insertions, 26 deletions

diff --git a/mm/gup.c b/mm/gup.c
index bcdefb977269..2370e2417d61 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -854,18 +854,13 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
  * FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.
  */
 long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
-		unsigned long start, unsigned long nr_pages, int write,
-		int force, struct page **pages, struct vm_area_struct **vmas)
+		unsigned long start, unsigned long nr_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(tsk, mm, start, nr_pages,
-				       pages, vmas, NULL, false, flags);
+				       pages, vmas, NULL, false,
+				       gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages);
 
diff --git a/mm/memory.c b/mm/memory.c
index 5aee9ec8b8c6..13142accda4f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3715,6 +3715,10 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 {
 	struct vm_area_struct *vma;
 	void *old_buf = buf;
+	unsigned int flags = FOLL_FORCE;
+
+	if (write)
+		flags |= FOLL_WRITE;
 
 	down_read(&mm->mmap_sem);
 	/* ignore errors, just check how much was successfully transferred */
@@ -3724,7 +3728,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 		struct page *page = NULL;
 
 		ret = get_user_pages(tsk, mm, addr, 1,
-				write, 1, &page, &vma);
+				flags, &page, &vma);
 		if (ret <= 0) {
 #ifndef CONFIG_HAVE_IOREMAP_PROT
 			break;
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index be9840bf11d1..44134ba6fb53 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -818,7 +818,7 @@ static int lookup_node(struct mm_struct *mm, unsigned long addr)
 	struct page *p;
 	int err;
 
-	err = get_user_pages(current, mm, addr & PAGE_MASK, 1, 0, 0, &p, NULL);
+	err = get_user_pages(current, mm, addr & PAGE_MASK, 1, 0, &p, NULL);
 	if (err >= 0) {
 		err = page_to_nid(p);
 		put_page(p);
diff --git a/mm/nommu.c b/mm/nommu.c
index 6cbb985238c4..073ea36abc21 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -184,18 +184,11 @@ finish_or_fault:
  */
 long get_user_pages(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)
 {
-	int flags = 0;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
-	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
-				NULL);
+	return __get_user_pages(tsk, mm, start, nr_pages,
+				gup_flags, pages, vmas, NULL);
 }
 EXPORT_SYMBOL(get_user_pages);
 
@@ -204,10 +197,7 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
 			   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,
+	return get_user_pages(tsk, mm, start, nr_pages, gup_flags,
 			      pages, NULL);
 }
 EXPORT_SYMBOL(get_user_pages_locked);