Permalink
Browse files

mm: remove write/force parameters from __get_user_pages_locked()

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: 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>
  • Loading branch information...
lorenzo-stoakes authored and torvalds committed Oct 13, 2016
1 parent 19be0ea commit 859110d7497cdd0e6b21010d6f777049d676382c
Showing with 33 additions and 14 deletions.
  1. +33 −14 mm/gup.c
@@ -739,7 +739,6 @@ 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,
@@ -757,10 +756,6 @@ 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;
@@ -856,9 +851,15 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, 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,
write, force, pages, NULL, locked, true,
FOLL_TOUCH);
pages, NULL, locked, true, flags);
}
EXPORT_SYMBOL(get_user_pages_locked);

@@ -879,9 +880,15 @@ __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;
@@ -973,9 +980,15 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
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 | FOLL_REMOTE);
unsigned int flags = FOLL_TOUCH | FOLL_REMOTE;

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_remote);

@@ -989,9 +1002,15 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
int write, int force, 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,
write, force, pages, vmas, NULL, false,
FOLL_TOUCH);
pages, vmas, NULL, false, flags);
}
EXPORT_SYMBOL(get_user_pages);

0 comments on commit 859110d

Please sign in to comment.