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

The userptr put_pages can be called from inside try_to_unmap, and so
enters with the page lock held on one of the object's backing pages. We
cannot take the page lock ourselves for fear of recursion.

Reported-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reported-by: Martin Wilck <Martin.Wilck@suse.com>
Reported-by: Leo Kraav <leho@kraav.com>
Fixes: aa56a292ce62 ("drm/i915/userptr: Acquire the page lock around set_page_dirty()")
References: https://bugzilla.kernel.org/show_bug.cgi?id=203317
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
index 2caa594322bc3f977e6d5720bf1f4a545fd89b43..528b6167833456d9fc6c5a0f8a53197c980a80d1 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
@@ -664,15 +664,7 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
 
        for_each_sgt_page(page, sgt_iter, pages) {
                if (obj->mm.dirty)
-                       /*
-                        * 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);
+                       set_page_dirty(page);
 
                mark_page_accessed(page);
                put_page(page);