From: John Hubbard <jhubbard@xxxxxxxxxx> Subject: mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote() Convert process_vm_access to use the new pin_user_pages_remote() call, which sets FOLL_PIN. Setting FOLL_PIN is now required for code that requires tracking of pinned pages. Also, release the pages via put_user_page*(). Also, rename "pages" to "pinned_pages", as this makes for easier reading of process_vm_rw_single_vec(). Link: http://lkml.kernel.org/r/20200107224558.2362728-15-jhubbard@xxxxxxxxxx Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Reviewed-by: Jérôme Glisse <jglisse@xxxxxxxxxx> Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx> Cc: Alex Williamson <alex.williamson@xxxxxxxxxx> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> Cc: Björn Töpel <bjorn.topel@xxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Hans Verkuil <hverkuil-cisco@xxxxxxxxx> Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Cc: Jason Gunthorpe <jgg@xxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> Cc: Leon Romanovsky <leonro@xxxxxxxxxxxx> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/process_vm_access.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) --- a/mm/process_vm_access.c~mm-process_vm_access-set-foll_pin-via-pin_user_pages_remote +++ a/mm/process_vm_access.c @@ -42,12 +42,11 @@ static int process_vm_rw_pages(struct pa if (copy > len) copy = len; - if (vm_write) { + if (vm_write) copied = copy_page_from_iter(page, offset, copy, iter); - set_page_dirty_lock(page); - } else { + else copied = copy_page_to_iter(page, offset, copy, iter); - } + len -= copied; if (copied < copy && iov_iter_count(iter)) return -EFAULT; @@ -96,7 +95,7 @@ static int process_vm_rw_single_vec(unsi flags |= FOLL_WRITE; while (!rc && nr_pages && iov_iter_count(iter)) { - int pages = min(nr_pages, max_pages_per_loop); + int pinned_pages = min(nr_pages, max_pages_per_loop); int locked = 1; size_t bytes; @@ -106,14 +105,15 @@ static int process_vm_rw_single_vec(unsi * current/current->mm */ down_read(&mm->mmap_sem); - pages = get_user_pages_remote(task, mm, pa, pages, flags, - process_pages, NULL, &locked); + pinned_pages = pin_user_pages_remote(task, mm, pa, pinned_pages, + flags, process_pages, + NULL, &locked); if (locked) up_read(&mm->mmap_sem); - if (pages <= 0) + if (pinned_pages <= 0) return -EFAULT; - bytes = pages * PAGE_SIZE - start_offset; + bytes = pinned_pages * PAGE_SIZE - start_offset; if (bytes > len) bytes = len; @@ -122,10 +122,12 @@ static int process_vm_rw_single_vec(unsi vm_write); len -= bytes; start_offset = 0; - nr_pages -= pages; - pa += pages * PAGE_SIZE; - while (pages) - put_page(process_pages[--pages]); + nr_pages -= pinned_pages; + pa += pinned_pages * PAGE_SIZE; + + /* If vm_write is set, the pages need to be made dirty: */ + put_user_pages_dirty_lock(process_pages, pinned_pages, + vm_write); } return rc; _
