| Message ID | 20200527223243.884385-3-jhubbard@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/gup: introduce pin_user_pages_locked(), use it in frame_vector.c | expand |
On 28.05.20 00:32, John Hubbard wrote: > This code was using get_user_pages*(), and all of the callers so far > were in a "Case 2" scenario (DMA/RDMA), using the categorization > from [1]. That means that it's time to convert the get_user_pages*() + > put_page() calls to pin_user_pages*() + unpin_user_pages() calls. > > There is some helpful background in [2]: basically, this is a small > part of fixing a long-standing disconnect between pinning pages, and > file systems' use of those pages. > > [1] Documentation/core-api/pin_user_pages.rst > > [2] "Explicit pinning of user-space pages": > https://lwn.net/Articles/807108/ > > Signed-off-by: John Hubbard <jhubbard@nvidia.com> > --- > mm/frame_vector.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/mm/frame_vector.c b/mm/frame_vector.c > index c431ca81dad5..4107dbca0056 100644 > --- a/mm/frame_vector.c > +++ b/mm/frame_vector.c > @@ -72,7 +72,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { > vec->got_ref = true; > vec->is_pfns = false; > - ret = get_user_pages_locked(start, nr_frames, > + ret = pin_user_pages_locked(start, nr_frames, > gup_flags, (struct page **)(vec->ptrs), &locked); > goto out; > } > @@ -122,7 +122,6 @@ EXPORT_SYMBOL(get_vaddr_frames); > */ > void put_vaddr_frames(struct frame_vector *vec) > { > - int i; > struct page **pages; > > if (!vec->got_ref) > @@ -135,8 +134,8 @@ void put_vaddr_frames(struct frame_vector *vec) > */ > if (WARN_ON(IS_ERR(pages))) > goto out; > - for (i = 0; i < vec->nr_frames; i++) > - put_page(pages[i]); > + > + unpin_user_pages(pages, vec->nr_frames); > vec->got_ref = false; > out: > vec->nr_frames = 0; > Not familiar with this code, but from what I can tell this LGTM.
diff --git a/mm/frame_vector.c b/mm/frame_vector.c index c431ca81dad5..4107dbca0056 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -72,7 +72,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { vec->got_ref = true; vec->is_pfns = false; - ret = get_user_pages_locked(start, nr_frames, + ret = pin_user_pages_locked(start, nr_frames, gup_flags, (struct page **)(vec->ptrs), &locked); goto out; } @@ -122,7 +122,6 @@ EXPORT_SYMBOL(get_vaddr_frames); */ void put_vaddr_frames(struct frame_vector *vec) { - int i; struct page **pages; if (!vec->got_ref) @@ -135,8 +134,8 @@ void put_vaddr_frames(struct frame_vector *vec) */ if (WARN_ON(IS_ERR(pages))) goto out; - for (i = 0; i < vec->nr_frames; i++) - put_page(pages[i]); + + unpin_user_pages(pages, vec->nr_frames); vec->got_ref = false; out: vec->nr_frames = 0;
This code was using get_user_pages*(), and all of the callers so far were in a "Case 2" scenario (DMA/RDMA), using the categorization from [1]. That means that it's time to convert the get_user_pages*() + put_page() calls to pin_user_pages*() + unpin_user_pages() calls. There is some helpful background in [2]: basically, this is a small part of fixing a long-standing disconnect between pinning pages, and file systems' use of those pages. [1] Documentation/core-api/pin_user_pages.rst [2] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/ Signed-off-by: John Hubbard <jhubbard@nvidia.com> --- mm/frame_vector.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)