Hi Dan,
On Thu, 25 Aug 2022 10:49:27 +0300, Dan Carpenter wrote:
> 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...
Sorry for late response and thanks for your bug report. Yes, that's
my fault. I'll prepare the patch.
Thanks,
Shigeru
>
> 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
>
