__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.
Fixes: 61c63c2076d9 (mm/gup.c: simplify and fix check_and_migrate_movable_pages() return codes)
CC: Alistair Popple <[email protected]>
Reported-by: [email protected]
Reviewed-by: John Hubbard <[email protected]>
Signed-off-by: Shigeru Yoshida <[email protected]>
---
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)
--
2.37.2
Shigeru Yoshida <[email protected]> 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.
> 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:
Reviewed-by: Alistair Popple <[email protected]>
> CC: Alistair Popple <[email protected]>
> Reported-by: [email protected]
> Reviewed-by: John Hubbard <[email protected]>
> Signed-off-by: Shigeru Yoshida <[email protected]>
> ---
> 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)
On Tue, 23 Aug 2022 11:15:29 +1000 Alistair Popple <[email protected]> wrote:
> > 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?
Yup. That's why we include the patch title as well as its hash.
On Tue, 23 Aug 2022 11:15:29 +1000, Alistair Popple wrote:
>
> Shigeru Yoshida <[email protected]> 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 <[email protected]>
>
>> CC: Alistair Popple <[email protected]>
>> Reported-by: [email protected]
>> Reviewed-by: John Hubbard <[email protected]>
>> Signed-off-by: Shigeru Yoshida <[email protected]>
>> ---
>> 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)
>