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Commit 6a3c9524 authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Greg Kroah-Hartman
Browse files

mm: remove write/force parameters from __get_user_pages_locked() 



commit 859110d7497cdd0e6b21010d6f777049d676382c upstream.

This removes the redundant 'write' and 'force' parameters from
__get_user_pages_locked() 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: default avatarLorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 4.4:
 - Drop change in get_user_pages_remote()
 - Adjust context]
Signed-off-by: default avatarBen Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8aca7715

mm/gup.c

+26 −11
Original line number Diff line number Diff line
@@ -627,7 +627,6 @@ static __always_inline 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,

						struct vm_area_struct **vmas,

						int *locked, bool notify_drop,
@@ -645,10 +644,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, 


	if (pages)

		flags |= FOLL_GET;

	if (write)

		flags |= FOLL_WRITE;

	if (force)

		flags |= FOLL_FORCE;



	pages_done = 0;

	lock_dropped = false;
@@ -745,8 +740,15 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm, 
			   int write, int force, struct page **pages,

			   int *locked)

{

	return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,

				       pages, NULL, locked, true, FOLL_TOUCH);

	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);

}

EXPORT_SYMBOL(get_user_pages_locked);
@@ -767,9 +769,15 @@ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct m 
{

	long ret;

	int locked = 1;



	if (write)

		gup_flags |= FOLL_WRITE;

	if (force)

		gup_flags |= FOLL_FORCE;



	down_read(&mm->mmap_sem);

	ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,

				      pages, NULL, &locked, false, gup_flags);

	ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL,

				      &locked, false, gup_flags);

	if (locked)

		up_read(&mm->mmap_sem);

	return ret;
@@ -861,8 +869,15 @@ 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)

{

	return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,

				       pages, vmas, NULL, false, FOLL_TOUCH);

	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);

}

EXPORT_SYMBOL(get_user_pages);