tree f172eb5b81e958457422d74e66587bf0071ddebe
parent 2bd6bf03f4c1c59381d62c61d03f6cc3fe71f66e
author Petar Penkov <ppenkov@google.com> 1504030832 -0700
committer Al Viro <viro@zeniv.linux.org.uk> 1505964468 -0400

iov_iter: fix page_copy_sane for compound pages

Issue is that if the data crosses a page boundary inside a compound
page, this check will incorrectly trigger a WARN_ON.

To fix this, compute the order using the head of the compound page and
adjust the offset to be relative to that head.

Fixes: 72e809ed81ed ("iov_iter: sanity checks for copy to/from page
primitives")

Signed-off-by: Petar Penkov <ppenkov@google.com>
CC: Al Viro <viro@zeniv.linux.org.uk>
CC: Eric Dumazet <edumazet@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>