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

BugLink: https://bugs.launchpad.net/bugs/1811080

commit c164154f upstream.

This removes the 'write' and 'force' use from get_user_pages_unlocked()
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>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 4.4:
 - Also update calls from process_vm_rw_single_vec() and async_pf_execute()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

arch/mips/mm/gup.c

@@ -303,7 +303,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 
 	ret = get_user_pages_unlocked(current, mm, start,
 				      (end - start) >> PAGE_SHIFT,
-				      write, 0, pages);
+				      pages, write ? FOLL_WRITE : 0);
 
 	/* Have to be a bit careful with return values */
 	if (nr > 0) {

arch/s390/mm/gup.c

@@ -241,7 +241,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	start += nr << PAGE_SHIFT;
 	pages += nr;
 	ret = get_user_pages_unlocked(current, mm, start,
-			     nr_pages - nr, write, 0, pages);
+			     nr_pages - nr, pages, write ? FOLL_WRITE : 0);
 	/* Have to be a bit careful with return values */
 	if (nr > 0)
 		ret = (ret < 0) ? nr : ret + nr;

arch/sh/mm/gup.c

@@ -258,7 +258,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 		pages += nr;
 
 		ret = get_user_pages_unlocked(current, mm, start,
-			(end - start) >> PAGE_SHIFT, write, 0, pages);
+			(end - start) >> PAGE_SHIFT, pages,
+			write ? FOLL_WRITE : 0);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {

arch/sparc/mm/gup.c

@@ -250,7 +250,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 		pages += nr;
 
 		ret = get_user_pages_unlocked(current, mm, start,
-			(end - start) >> PAGE_SHIFT, write, 0, pages);
+			(end - start) >> PAGE_SHIFT, pages,
+			write ? FOLL_WRITE : 0);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {

arch/x86/mm/gup.c

@@ -388,7 +388,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 
 		ret = get_user_pages_unlocked(current, mm, start,
 					      (end - start) >> PAGE_SHIFT,
-					      write, 0, pages);
+					      pages, write ? FOLL_WRITE : 0);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {

drivers/media/pci/ivtv/ivtv-udma.c

@@ -125,7 +125,8 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
 
 	/* Get user pages for DMA Xfer */
 	err = get_user_pages_unlocked(current, current->mm,
-			user_dma.uaddr, user_dma.page_count, 0, 1, dma->map);
+			user_dma.uaddr, user_dma.page_count, dma->map,
+			FOLL_FORCE);
 
 	if (user_dma.page_count != err) {
 		IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n",

drivers/media/pci/ivtv/ivtv-yuv.c

@@ -76,13 +76,13 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
 
 	/* Get user pages for DMA Xfer */
 	y_pages = get_user_pages_unlocked(current, current->mm,
-				y_dma.uaddr, y_dma.page_count, 0, 1,
-				&dma->map[0]);
+				y_dma.uaddr, y_dma.page_count,
+				&dma->map[0], FOLL_FORCE);
 	uv_pages = 0; /* silence gcc. value is set and consumed only if: */
 	if (y_pages == y_dma.page_count) {
 		uv_pages = get_user_pages_unlocked(current, current->mm,
-					uv_dma.uaddr, uv_dma.page_count, 0, 1,
-					&dma->map[y_pages]);
+					uv_dma.uaddr, uv_dma.page_count,
+					&dma->map[y_pages], FOLL_FORCE);
 	}
 
 	if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) {

drivers/scsi/st.c

@@ -4821,9 +4821,8 @@ static int sgl_map_user_pages(struct st_buffer *STbp,
 		current->mm,
 		uaddr,
 		nr_pages,
-		rw == READ,
-		0, /* don't force */
-		pages);
+		pages,
+		rw == READ ? FOLL_WRITE : 0); /* don't force */
 
 	/* Errors and no page mapped should return here */
 	if (res < nr_pages)

drivers/video/fbdev/pvr2fb.c

@@ -687,7 +687,7 @@ static ssize_t pvr2fb_write(struct fb_info *info, const char *buf,
 		return -ENOMEM;
 
 	ret = get_user_pages_unlocked(current, current->mm, (unsigned long)buf,
-				      nr_pages, WRITE, 0, pages);
+				      nr_pages, pages, FOLL_WRITE);
 
 	if (ret < nr_pages) {
 		nr_pages = ret;

include/linux/mm.h

@@ -1232,7 +1232,7 @@ long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			       struct page **pages, unsigned int gup_flags);
 long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 		    unsigned long start, unsigned long nr_pages,
-		    int write, int force, struct page **pages);
+		    struct page **pages, unsigned int gup_flags);
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			struct page **pages);
 

mm/gup.c

@@ -797,17 +797,10 @@ EXPORT_SYMBOL(__get_user_pages_unlocked);
  */
 long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			     unsigned long start, unsigned long nr_pages,
-			     int write, int force, struct page **pages)
+			     struct page **pages, unsigned int gup_flags)
 {
-	unsigned int flags = FOLL_TOUCH;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
 	return __get_user_pages_unlocked(tsk, mm, start, nr_pages,
-					 pages, flags);
+					 pages, gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
@@ -1427,7 +1420,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 		pages += nr;
 
 		ret = get_user_pages_unlocked(current, mm, start,
-					      nr_pages - nr, write, 0, pages);
+					      nr_pages - nr, pages,
+					      write ? FOLL_WRITE : 0);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {

mm/nommu.c

@@ -224,17 +224,10 @@ EXPORT_SYMBOL(__get_user_pages_unlocked);
 
 long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			     unsigned long start, unsigned long nr_pages,
-			     int write, int force, struct page **pages)
+			     struct page **pages, unsigned int gup_flags)
 {
-	unsigned int flags = 0;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
 	return __get_user_pages_unlocked(tsk, mm, start, nr_pages,
-					 pages, flags);
+					 pages, gup_flags);
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 

mm/process_vm_access.c

@@ -88,19 +88,23 @@ static int process_vm_rw_single_vec(unsigned long addr,
 	ssize_t rc = 0;
 	unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
 		/ sizeof(struct pages *);
+	unsigned int flags = 0;
 
 	/* Work out address and page range required */
 	if (len == 0)
 		return 0;
 	nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
 
+	if (vm_write)
+		flags |= FOLL_WRITE;
+
 	while (!rc && nr_pages && iov_iter_count(iter)) {
 		int pages = min(nr_pages, max_pages_per_loop);
 		size_t bytes;
 
 		/* Get the pages we're interested in */
 		pages = get_user_pages_unlocked(task, mm, pa, pages,
-						vm_write, 0, process_pages);
+						process_pages, flags);
 		if (pages <= 0)
 			return -EFAULT;
 

mm/util.c

@@ -278,7 +278,7 @@ int __weak get_user_pages_fast(unsigned long start,
 {
 	struct mm_struct *mm = current->mm;
 	return get_user_pages_unlocked(current, mm, start, nr_pages,
-				       write, 0, pages);
+				       pages, write ? FOLL_WRITE : 0);
 }
 EXPORT_SYMBOL_GPL(get_user_pages_fast);
 

net/ceph/pagevec.c

@@ -26,7 +26,7 @@ struct page **ceph_get_direct_page_vector(const void __user *data,
 	while (got < num_pages) {
 		rc = get_user_pages_unlocked(current, current->mm,
 		    (unsigned long)data + ((unsigned long)got * PAGE_SIZE),
-		    num_pages - got, write_page, 0, pages + got);
+		    num_pages - got, pages + got, write_page ? FOLL_WRITE : 0);
 		if (rc < 0)
 			break;
 		BUG_ON(rc == 0);

virt/kvm/async_pf.c

@@ -80,7 +80,7 @@ static void async_pf_execute(struct work_struct *work)
 
 	might_sleep();
 
-	get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL);
+	get_user_pages_unlocked(NULL, mm, addr, 1, NULL, FOLL_WRITE);
 	kvm_async_page_present_sync(vcpu, apf);
 
 	spin_lock(&vcpu->async_pf.lock);