4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Lorenzo Stoakes <[email protected]> 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 <[email protected]> Reviewed-by: Jan Kara <[email protected]> Acked-by: Michal Hocko <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> [bwh: Backported to 4.4: - Drop change in get_user_pages_remote() - Adjust context] Signed-off-by: Ben Hutchings <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/gup.c | 37 ++++++++++++++++++++++++++----------- 1 file changed, 26 insertions(+), 11 deletions(-) --- a/mm/gup.c +++ b/mm/gup.c @@ -627,7 +627,6 @@ static __always_inline long __get_user_p 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_p 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_s 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_un { 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 * 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);
