From: Alice Ryhl Date: Tue, 2 Dec 2025 11:24:24 +0000 (+0000) Subject: rust_binder: remove spin_lock() in rust_shrink_free_page() X-Git-Tag: v6.19-rc5~2^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=361e0ff456a8daf9753c18030533256e4133ce7a;p=thirdparty%2Fkernel%2Flinux.git rust_binder: remove spin_lock() in rust_shrink_free_page() 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 Fixes: eafedbc7c050 ("rust_binder: add Rust Binder driver") Signed-off-by: Alice Ryhl Link: https://patch.msgid.link/20251202-binder-shrink-unspin-v1-1-263efb9ad625@google.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/android/binder/page_range.rs b/drivers/android/binder/page_range.rs index 9379038f61f51..fdd97112ef5c8 100644 --- a/drivers/android/binder/page_range.rs +++ b/drivers/android/binder/page_range.rs @@ -727,8 +727,5 @@ unsafe extern "C" fn rust_shrink_free_page( 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 }