evie/android_kernel_oneplus_msm8998
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mm: remove write/force parameters from __get_user_pages_locked()

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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: 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:
 - Drop change in get_user_pages_remote()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lorenzo Stoakes 2016-10-13 01:20:11 +01:00 • committed by Greg Kroah-Hartman
parent 8aca77150a
commit 6a3c9524df
1 changed files with 26 additions and 11 deletions
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37
mm/gup.c
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@ -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);