When forward-porting Rust Binder to 6.18, I neglected to take commit fb56fdf8b9a2 ("mm/list_lru: split the lock to per-cgroup scope") into account, and apparently I did not end up running the shrinker callback when I sanity tested the driver before submission. This leads to crashes like the following:

============================================ WARNING: possible recursive locking detected 6.18.0-mainline-maybe-dirty #1 Tainted: G IO -------------------------------------------- kswapd0/68 is trying to acquire lock: ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: lock_list_lru_of_memcg+0x128/0x230

but task is already holding lock: ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: rust_helper_spin_lock+0xd/0x20

other info that might help us debug this: Possible unsafe locking scenario:

CPU0 ---- lock(&l->lock); lock(&l->lock);

*** DEADLOCK ***

May be due to missing lock nesting notation

3 locks held by kswapd0/68: #0: ffffffff90d2e260 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x597/0x1160 #1: ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: rust_helper_spin_lock+0xd/0x20 #2: ffffffff90cf3680 (rcu_read_lock){....}-{1:2}, at: lock_list_lru_of_memcg+0x2d/0x230

To fix this, remove the spin_lock() call from rust_shrink_free_page().

Cc: stable@vger.kernel.org Fixes: eafedbc7c050 ("rust_binder: add Rust Binder driver") Signed-off-by: Alice Ryhl aliceryhl@google.com --- drivers/android/binder/page_range.rs | 3 --- 1 file changed, 3 deletions(-)

diff --git a/drivers/android/binder/page_range.rs b/drivers/android/binder/page_range.rs index 9379038f61f513c51ebed6c7e7b6fde32e5b8d06..fdd97112ef5c8b2341e498dc3567b659f05e3fd7 100644 --- a/drivers/android/binder/page_range.rs +++ b/drivers/android/binder/page_range.rs @@ -727,8 +727,5 @@ fn drop(self: Pin<&mut Self>) { drop(mm); drop(page);

- // SAFETY: We just unlocked the lru lock, but it should be locked when we return. - unsafe { bindings::spin_lock(&raw mut (*lru).lock) }; - LRU_REMOVED_ENTRY }

--- base-commit: 82d12088c297fa1cef670e1718b3d24f414c23f7 change-id: 20251202-binder-shrink-unspin-1ee9872cc2ed

Best regards,