mm/mmu_notifier: finish non-blocking interval invalidation on error

When an ordinary MMU notifier rejects a non-blocking invalidation, the
interval invalidation started beforehand is left unfinished: the caller
skips mmu_notifier_invalidate_range_end(). Subsequent interval notifier
operations can then wait forever.

The only in-tree trigger is nouveau SVM, which uses both notifier types
and rejects non-blocking invalidations. Reaping via the OOM reaper or
process_mrelease() can therefore leave the GPU fault worker stuck,
holding a reference that prevents the dying process's address space
and memory from being freed.

End the interval invalidation when an ordinary notifier fails a
non-blocking invalidation, like mn_itree_invalidate() already does when
an interval notifier fails. Make that handling clearer in the
documentation of mmu_notifier_invalidate_range_start_nonblock().

Fix generated by an LLM and sent by Josef Bacik in private.

Fixes: 99cb252f5e68 ("mm/mmu_notifier: add an interval tree notifier")
Cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ david: simplify description, update function doc ]
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Tested-by: Muhammad Usama Anjum <usama.anjum@arm.com>
Link: https://patch.msgid.link/20261031-fixes_core-v3-28-d6437171ecc3@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

0 files changed, 0 insertions, 0 deletions