From: John Hubbard Date: Mon, 8 Jun 2020 04:41:15 +0000 (-0700) Subject: vhost: convert get_user_pages() --> pin_user_pages() X-Git-Tag: v5.15~3652^2~30 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=690623e1b49603bdd3df4532b7911a2ce26fb4c4;p=mirror_ubuntu-kernels.git vhost: convert get_user_pages() --> pin_user_pages() This code was using get_user_pages*(), in approximately a "Case 5" scenario (accessing the data within a page), 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 Signed-off-by: Andrew Morton Reviewed-by: Jan Kara Acked-by: Michael S. Tsirkin Acked-by: Pankaj Gupta Cc: Jason Wang Cc: Dave Chinner Cc: Jérôme Glisse Cc: Jonathan Corbet Cc: Souptick Joarder Cc: Vlastimil Babka Link: http://lkml.kernel.org/r/20200529234309.484480-3-jhubbard@nvidia.com Signed-off-by: Linus Torvalds --- diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 21a59b598ed8..596132a96cd5 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1762,15 +1762,14 @@ static int set_bit_to_user(int nr, void __user *addr) int bit = nr + (log % PAGE_SIZE) * 8; int r; - r = get_user_pages_fast(log, 1, FOLL_WRITE, &page); + r = pin_user_pages_fast(log, 1, FOLL_WRITE, &page); if (r < 0) return r; BUG_ON(r != 1); base = kmap_atomic(page); set_bit(bit, base); kunmap_atomic(base); - set_page_dirty_lock(page); - put_page(page); + unpin_user_pages_dirty_lock(&page, 1, true); return 0; }