From 08aac95322470b045a4c420dca371069198d975a Mon Sep 17 00:00:00 2001
From: Matthew Auld <matthew.auld@intel.com>
Date: Mon, 23 Mar 2020 13:08:21 +0000
Subject: drm/i915/selftests: mark huge_gem_object as not shrinkable
Git-commit: 8493e110a637c273b4d38e79f7ce3c3ad1812931
Patch-mainline: v5.8-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
It looks like some callers expect a non-volatile object, that they do not
want the contents of the pages lost if they happen to not be looking at it.
The shrinker however sees that we mark the pages as DONTNEED and
believes that it can freely reap them. However, since the huge object
use plain pages, they cannot be swapped out as they have no backing
storge, and the only way we can shrink them is by discarding the
contents. In light of the callers wanting to keep the contents around,
both IS_SHRINKABLE and marking the pages as volatile are incorrect.
If we drop the IS_SHRINKABLE flag we avoid the immediate issue of the
shrinker accidentally removing valuable content. We will have to
remember that a huge object is not suitable for exercising the shrinker
interaction -- although we can introduce a shrinkable one if we require.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200323130821.47914-1-matthew.auld@intel.com
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gem/selftests/huge_gem_object.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_gem_object.c b/drivers/gpu/drm/i915/gem/selftests/huge_gem_object.c
index fa16f2c3f3ac..2b46c6530da9 100644
--- a/drivers/gpu/drm/i915/gem/selftests/huge_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/selftests/huge_gem_object.c
@@ -88,8 +88,7 @@ static void huge_put_pages(struct drm_i915_gem_object *obj,
}
static const struct drm_i915_gem_object_ops huge_ops = {
- .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE |
- I915_GEM_OBJECT_IS_SHRINKABLE,
+ .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE,
.get_pages = huge_get_pages,
.put_pages = huge_put_pages,
};
--
2.28.0