mm/mmu_notifier: set ->mm only after mmgrab()

Radeon uses a non-NULL notifier->mm to decide whether to call
mmu_interval_notifier_remove() when freeing a buffer object.
__mmu_interval_notifier_insert() sets ->mm before validating the range,
so a wrapping userptr range can leave ->mm set after insertion fails.
Cleanup then tries to remove an unregistered notifier for which no mm
reference was acquired.

Set ->mm only after mmgrab(), once insertion can no longer fail. While
we could fix radeon's code instead, setting ->mm on success only makes
the code more robust.

Fix generated by an LLM and sent by Chris Mason in private.

Fixes: 3506ff69c3ec ("drm/radeon: use mmu_interval_notifier_insert")
Cc: stable@vger.kernel.org
Signed-off-by: Chris Mason <mason@kernel.org>
[ david: simplify description ]
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
Tested-by: Gregory Price (Meta) <gourry@gourry.net>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Tested-by: Muhammad Usama Anjum <usama.anjum@arm.com>
Link: https://patch.msgid.link/20261031-fixes_core-v3-29-d6437171ecc3@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

0 files changed, 0 insertions, 0 deletions