drm/i915/userptr: Acquire the page lock around set_page_dirty()
authorChris Wilson <chris@chris-wilson.co.uk>
Mon, 8 Jul 2019 14:03:27 +0000 (15:03 +0100)
committerJani Nikula <jani.nikula@intel.com>
Mon, 29 Jul 2019 12:37:50 +0000 (15:37 +0300)
commitaa56a292ce623734ddd30f52d73f527d1f3529b5
tree6f088aca904cc5649e32ed69955565036bbaf21f
parent5f4c82c89ff0e11b31561aa7e547acb10bf650c2
drm/i915/userptr: Acquire the page lock around set_page_dirty()

set_page_dirty says:

For pages with a mapping this should be done under the page lock
for the benefit of asynchronous memory errors who prefer a
consistent dirty state. This rule can be broken in some special
cases, but should be better not to.

Under those rules, it is only safe for us to use the plain set_page_dirty
calls for shmemfs/anonymous memory. Userptr may be used with real
mappings and so needs to use the locked version (set_page_dirty_lock).

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203317
Fixes: 5cc9ed4b9a7a ("drm/i915: Introduce mapping of user pages into video memory (userptr) ioctl")
References: 6dcc693bc57f ("ext4: warn when page is dirtied without buffers")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190708140327.26825-1-chris@chris-wilson.co.uk
(cherry picked from commit cb6d7c7dc7ff8cace666ddec66334117a6068ce2)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
drivers/gpu/drm/i915/gem/i915_gem_userptr.c