Messages in this thread | | | Subject | Re: [PATCH v2] mm: gup: fix comment of __get_user_pages() | From | John Hubbard <> | Date | Mon, 28 Oct 2019 11:50:31 -0700 |
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On 10/24/19 8:04 AM, Liu Xiang wrote: > Fix comment of __get_user_pages() and make it more clear. > > Suggested-by: John Hubbard <jhubbard@nvidia.com> > Signed-off-by: Liu Xiang <liuxiang_1999@126.com> > --- > > Changes in v2: > as suggested by John, rewrite the comment about return value. > > mm/gup.c | 16 +++++++++++----- > 1 file changed, 11 insertions(+), 5 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 8f236a3..bc6a254 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -734,11 +734,17 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) > * Or NULL if the caller does not require them. > * @nonblocking: whether waiting for disk IO or mmap_sem contention > * > - * Returns number of pages pinned. This may be fewer than the number > - * requested. If nr_pages is 0 or negative, returns 0. If no pages > - * were pinned, returns -errno. Each page returned must be released > - * with a put_page() call when it is finished with. vmas will only > - * remain valid while mmap_sem is held. > + * Returns either number of pages pinned (which may be less than the > + * number requested), or an error. Details about the return value: > + * > + * -- If nr_pages is 0, returns 0. > + * -- If nr_pages is >0, but no pages were pinned, returns -errno. > + * -- If nr_pages is >0, and some pages were pinned, returns the number of > + * pages pinned. Again, this may be less than nr_pages. > + * > + * The caller is responsible for releasing returned @pages, via put_page(). > + * > + * @vmas are valid only as long as mmap_sem is held.
Just remembered: this identical paragraph is also written in the get_user_pages_remote() comments. It would be ideal to apply the same fix to that identical blob of text.
thanks, -- John Hubbard NVIDIA
> * > * Must be called with mmap_sem held. It may be released. See below. > * >
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