mm: gup: add __get_user_pages_unlocked to customize gup_flags

Some callers (like KVM) may want to set the gup_flags like FOLL_HWPOSION
to get a proper -EHWPOSION retval instead of -EFAULT to take a more
appropriate action if get_user_pages runs into a memory failure.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 3 deletions

diff --git a/mm/nommu.c b/mm/nommu.c
index bfb690b0f986..4d1b8a199867 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -224,9 +224,10 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
-long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
-                             unsigned long start, unsigned long nr_pages,
-                             int write, int force, struct page **pages)
+long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+                               unsigned long start, unsigned long nr_pages,
+                               int write, int force, struct page **pages,
+                               unsigned int gup_flags)
 {
         long ret;
         down_read(&mm->mmap_sem);
@@ -235,6 +236,15 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
         up_read(&mm->mmap_sem);
         return ret;
 }
+EXPORT_SYMBOL(__get_user_pages_unlocked);
+
+long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+                             unsigned long start, unsigned long nr_pages,
+                             int write, int force, struct page **pages)
+{
+        return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,
+                                         force, pages, 0);
+}
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
 /**