From: Jason Gunthorpe <jgg@nvidia.com>
To: David Hildenbrand <david@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>,
Dongwon Kim <dongwon.kim@intel.com>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Hugh Dickins <hughd@google.com>,
Vivek Kasireddy <vivek.kasireddy@intel.com>,
dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
Peter Xu <peterx@redhat.com>,
Junxiao Chang <junxiao.chang@intel.com>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH v1 1/3] mm/gup: Introduce pin_user_pages_fd() for pinning shmem/hugetlbfs file pages
Date: Fri, 6 Oct 2023 15:43:23 -0300 [thread overview]
Message-ID: <20231006184323.GT682044@nvidia.com> (raw)
In-Reply-To: <4c272313-d2cd-fa29-3126-496636e14115@redhat.com>
On Fri, Oct 06, 2023 at 10:03:33AM +0200, David Hildenbrand wrote:
> > + *
> > + * Returns number of pages pinned. This would be equal to the number of
> > + * pages requested.
> > + * If nr_pages is 0 or negative, returns 0. If no pages were pinned, returns
> > + * -errno.
> > + */
> > +long pin_user_pages_fd(int fd, pgoff_t start, unsigned long nr_pages,
> > + unsigned int gup_flags, struct page **pages)
> > +{
> > + struct page *page;
> > + struct file *filep;
> > + unsigned int flags, i;
> > + long ret;
> > +
> > + if (nr_pages <= 0)
> > + return 0;
>
> I think we should just forbid that and use a WARN_ON_ONCE() here / return
> -EINVAL. So we'll never end up returning 0.
Why is the check even needed? It looked like it just runs through
normally and returns 0, that is fine..
Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: David Hildenbrand <david@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>,
dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
Mike Kravetz <mike.kravetz@oracle.com>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Hugh Dickins <hughd@google.com>, Peter Xu <peterx@redhat.com>,
Gerd Hoffmann <kraxel@redhat.com>,
Dongwon Kim <dongwon.kim@intel.com>,
Junxiao Chang <junxiao.chang@intel.com>
Subject: Re: [PATCH v1 1/3] mm/gup: Introduce pin_user_pages_fd() for pinning shmem/hugetlbfs file pages
Date: Fri, 6 Oct 2023 15:43:23 -0300 [thread overview]
Message-ID: <20231006184323.GT682044@nvidia.com> (raw)
In-Reply-To: <4c272313-d2cd-fa29-3126-496636e14115@redhat.com>
On Fri, Oct 06, 2023 at 10:03:33AM +0200, David Hildenbrand wrote:
> > + *
> > + * Returns number of pages pinned. This would be equal to the number of
> > + * pages requested.
> > + * If nr_pages is 0 or negative, returns 0. If no pages were pinned, returns
> > + * -errno.
> > + */
> > +long pin_user_pages_fd(int fd, pgoff_t start, unsigned long nr_pages,
> > + unsigned int gup_flags, struct page **pages)
> > +{
> > + struct page *page;
> > + struct file *filep;
> > + unsigned int flags, i;
> > + long ret;
> > +
> > + if (nr_pages <= 0)
> > + return 0;
>
> I think we should just forbid that and use a WARN_ON_ONCE() here / return
> -EINVAL. So we'll never end up returning 0.
Why is the check even needed? It looked like it just runs through
normally and returns 0, that is fine..
Jason
next prev parent reply other threads:[~2023-10-06 18:43 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-03 7:44 [PATCH v1 0/3] mm/gup: Introduce pin_user_pages_fd() for pinning shmem/hugetlbfs file pages Vivek Kasireddy
2023-10-03 7:44 ` Vivek Kasireddy
2023-10-03 7:44 ` [PATCH v1 1/3] " Vivek Kasireddy
2023-10-03 7:44 ` Vivek Kasireddy
2023-10-06 8:03 ` David Hildenbrand
2023-10-06 8:03 ` David Hildenbrand
2023-10-06 18:43 ` Jason Gunthorpe [this message]
2023-10-06 18:43 ` Jason Gunthorpe
2023-10-17 7:39 ` Kasireddy, Vivek
2023-10-17 7:39 ` Kasireddy, Vivek
2023-10-10 13:51 ` Jason Gunthorpe
2023-10-10 13:51 ` Jason Gunthorpe
2023-10-03 7:44 ` [PATCH v1 2/3] udmabuf: Pin the pages using pin_user_pages_fd() API Vivek Kasireddy
2023-10-03 7:44 ` Vivek Kasireddy
2023-10-03 7:44 ` [PATCH v1 3/3] selftests/dma-buf/udmabuf: Add tests to verify data after page migration Vivek Kasireddy
2023-10-03 7:44 ` Vivek Kasireddy
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