FAILED: Patch "drm/i915: Check before removing mm notifier" failed to apply to 6.8-stable tree

[Sasha Levin]

The patch below does not apply to the 6.8-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable at vger.kernel.org>.

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

>From db7bbd13f08774cde0332c705f042e327fe21e73 Mon Sep 17 00:00:00 2001
From: Nirmoy Das <nirmoy.das at intel.com>
Date: Mon, 19 Feb 2024 13:50:47 +0100
Subject: [PATCH] drm/i915: Check before removing mm notifier

Error in mmu_interval_notifier_insert() can leave a NULL
notifier.mm pointer. Catch that and return early.

Fixes: ed29c2691188 ("drm/i915: Fix userptr so we do not have to worry about obj->mm.lock, v7.")
Cc: <stable at vger.kernel.org> # v5.13+
[tursulin: Added Fixes and cc stable.]
Cc: Andi Shyti <andi.shyti at linux.intel.com>
Cc: Shawn Lee <shawn.c.lee at intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das at intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240219125047.28906-1-nirmoy.das@intel.com
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
index 0e21ce9d3e5ac..61abfb505766d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
@@ -349,6 +349,9 @@ i915_gem_userptr_release(struct drm_i915_gem_object *obj)
 {
 	GEM_WARN_ON(obj->userptr.page_ref);
 
+	if (!obj->userptr.notifier.mm)
+		return;
+
 	mmu_interval_notifier_remove(&obj->userptr.notifier);
 	obj->userptr.notifier.mm = NULL;
 }
-- 
2.43.0