On Tue, 23 Aug 2022 11:15:29 +1000, Alistair Popple wrote:
>
> Shigeru Yoshida <syoshida@xxxxxxxxxx> writes:
>
>> __get_user_pages_locked() may return the number of pages less than
>> nr_pages. So __gup_longterm_locked() have to return the number of
>> pages __get_user_pages_locked() returns if it succeeded, not nr_pages
>> requested.
>
> Thanks for fixing this, I've been out the last few days so just catching
> up. I think I missed that 'rc' was passed as nr_pages into
> check_and_migrate_movable_pages(). Will double check that I don't make
> the same mistake in my latest series.
Thank you so much for your review. Andrew has already applied the patch.
>> Fixes: 61c63c2076d9 (mm/gup.c: simplify and fix check_and_migrate_movable_pages() return codes)
>
> I couldn't find that SHA1, I'm guessing due to rebasing, etc. of
> mm-unstable? Not sure how that is dealt with, but feel free to also add:
Yes, actually this hash is from from linux-next tree.
Thanks,
Shigeru
> Reviewed-by: Alistair Popple <apopple@xxxxxxxxxx>
>
>> CC: Alistair Popple <apopple@xxxxxxxxxx>
>> Reported-by: syzbot+616ff0452fec30f4dcfd@xxxxxxxxxxxxxxxxxxxxxxxxx
>> Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
>> Signed-off-by: Shigeru Yoshida <syoshida@xxxxxxxxxx>
>> ---
>> mm/gup.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/gup.c b/mm/gup.c
>> index 5aa7531a703b..66582203220a 100644
>> --- a/mm/gup.c
>> +++ b/mm/gup.c
>> @@ -2068,22 +2068,24 @@ static long __gup_longterm_locked(struct mm_struct *mm,
>> unsigned int gup_flags)
>> {
>> unsigned int flags;
>> - long rc;
>> + long rc, nr_pinned_pages;
>>
>> if (!(gup_flags & FOLL_LONGTERM))
>> return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
>> NULL, gup_flags);
>> flags = memalloc_pin_save();
>> do {
>> - rc = __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
>> - NULL, gup_flags);
>> - if (rc <= 0)
>> + nr_pinned_pages =
>> + __get_user_pages_locked(mm, start, nr_pages, pages,
>> + vmas, NULL, gup_flags);
>> + if (nr_pinned_pages <= 0)
>> break;
>> - rc = check_and_migrate_movable_pages(rc, pages, gup_flags);
>> + rc = check_and_migrate_movable_pages(nr_pinned_pages, pages,
>> + gup_flags);
>> } while (rc == -EAGAIN);
>> memalloc_pin_restore(flags);
>>
>> - return rc ? rc : nr_pages;
>> + return rc ? rc : nr_pinned_pages;
>> }
>>
>> static bool is_valid_gup_flags(unsigned int gup_flags)
>
