mm: fix __gup_device_huge vs unmap
authorDan Williams <dan.j.williams@intel.com>
Fri, 20 Apr 2018 04:32:19 +0000 (21:32 -0700)
committerDan Williams <dan.j.williams@intel.com>
Tue, 22 May 2018 14:19:08 +0000 (07:19 -0700)
commita9b6de77b1a3ff729f7bfc54b2e17711776a416c
treeabf94e003816c5c99bb5792a8e636905a44ad48e
parente7638488434415aa478e78435cac8f0365737638
mm: fix __gup_device_huge vs unmap

get_user_pages_fast() for device pages is missing the typical validation
that all page references have been taken while the mapping was valid.
Without this validation truncate operations can not reliably coordinate
against new page reference events like O_DIRECT.

Cc: <stable@vger.kernel.org>
Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings")
Reported-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
mm/gup.c