[bug report] mm/gup.c: Fix return value for __gup_longterm_locked()

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Shigeru Yoshida,

The patch 35f9c4607f9e: "mm/gup.c: Fix return value for
__gup_longterm_locked()" from Aug 22, 2022, leads to the following
Smatch static checker warning:

	mm/gup.c:2089 __gup_longterm_locked()
	error: uninitialized symbol 'rc'.

mm/gup.c
    2064 static long __gup_longterm_locked(struct mm_struct *mm,
    2065                                   unsigned long start,
    2066                                   unsigned long nr_pages,
    2067                                   struct page **pages,
    2068                                   struct vm_area_struct **vmas,
    2069                                   unsigned int gup_flags)
    2070 {
    2071         unsigned int flags;
    2072         long rc, nr_pinned_pages;
    2073 
    2074         if (!(gup_flags & FOLL_LONGTERM))
    2075                 return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
    2076                                                NULL, gup_flags);
    2077         flags = memalloc_pin_save();
    2078         do {
    2079                 nr_pinned_pages = __get_user_pages_locked(mm, start, nr_pages,
    2080                                                           pages, vmas, NULL,
    2081                                                           gup_flags);
    2082                 if (nr_pinned_pages <= 0)


This doesn't work if if fails on the first iteration.  But also I'm
surprised that we are return -EAGAIN on subsequent iterations...

    2083                         break;
    2084                 rc = check_and_migrate_movable_pages(nr_pinned_pages, pages,
    2085                                                      gup_flags);
    2086         } while (rc == -EAGAIN);
    2087         memalloc_pin_restore(flags);
    2088 
--> 2089         return rc ? rc : nr_pinned_pages;
    2090 }

regards,
dan carpenter