This patch removes the 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 <lstoa...@gmail.com>
---
 mm/gup.c | 47 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 33 insertions(+), 14 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 96b2b2f..ba83942 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -729,7 +729,6 @@ 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,
@@ -747,10 +746,6 @@ 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;
@@ -846,9 +841,15 @@ 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);
 
@@ -869,9 +870,15 @@ __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;
@@ -963,9 +970,15 @@ 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);
 
@@ -979,9 +992,15 @@ 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);
 
-- 
2.10.0

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