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

This removes the 'write' and 'force' use from get_user_pages_locked()
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: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes 2016-10-13 01:20:14 +01:00 committed by Linus Torvalds
parent c164154f66
commit 3b913179c3
4 changed files with 15 additions and 12 deletions
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2
include/linux/mm.h
View File

@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
struct vm_area_struct **vmas);
long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages, int *locked);
unsigned int gup_flags, struct page **pages, int *locked);
long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags);

8
mm/frame_vector.c
View File

@ -41,10 +41,16 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
int ret = 0;
int err;
int locked;
unsigned int gup_flags = 0;
if (nr_frames == 0)
return 0;
if (write)
gup_flags |= FOLL_WRITE;
if (force)
gup_flags |= FOLL_FORCE;
if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
nr_frames = vec->nr_allocated;
@ -59,7 +65,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
vec->got_ref = true;
vec->is_pfns = false;
ret = get_user_pages_locked(start, nr_frames,
write, force, (struct page **)(vec->ptrs), &locked);
gup_flags, (struct page **)(vec->ptrs), &locked);
goto out;
}

12
mm/gup.c
View File

@ -848,18 +848,12 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
* up_read(&mm->mmap_sem);
*/
long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags, 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,
pages, NULL, locked, true, flags);
pages, NULL, locked, true,
gup_flags | FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages_locked);

5
mm/nommu.c
View File

@ -176,9 +176,12 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
EXPORT_SYMBOL(get_user_pages);
long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **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);
}
EXPORT_SYMBOL(get_user_pages_locked);