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drm/i915/userptr: Acquire the page lock around set_page_dirty()

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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: 5cc9ed4b9a ("drm/i915: Introduce mapping of user pages into video memory (userptr) ioctl")
References: 6dcc693bc5 ("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 cb6d7c7dc7)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Chris Wilson 2019-07-08 15:03:27 +01:00 committed by Jani Nikula
parent 5f4c82c89f
commit aa56a292ce
1 changed files with 9 additions and 1 deletions
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10
drivers/gpu/drm/i915/gem/i915_gem_userptr.c
View File

@ -664,7 +664,15 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
for_each_sgt_page(page, sgt_iter, pages) {
if (obj->mm.dirty)
set_page_dirty(page);
/*
* As this may not be anonymous memory (e.g. shmem)
* but exist on a real mapping, we have to lock
* the page in order to dirty it -- holding
* the page reference is not sufficient to
* prevent the inode from being truncated.
* Play safe and take the lock.
*/
set_page_dirty_lock(page);
mark_page_accessed(page);
put_page(page);