While developing IPPROTO_SMBDIRECT support for the code under fs/smb/common/smbdirect [1], I noticed false positives like this: [T79] ====================================================== [T79] WARNING: possible circular locking dependency detected [T79] 6.18.0-rc4-metze-kasan-lockdep.01+ #1 Tainted: G OE [T79] ------------------------------------------------------ [T79] kworker/2:0/79 is trying to acquire lock: [T79] ffff88801f968278 (sk_lock-AF_INET){+.+.}-{0:0}, at: sock_set_reuseaddr+0x14/0x70 [T79] but task is already holding lock: [T79] ffffffffc10f7230 (lock#9){+.+.}-{4:4}, at: rdma_listen+0x3d2/0x740 [rdma_cm] [T79] which lock already depends on the new lock. [T79] the existing dependency chain (in reverse order) is: [T79] -> #1 (lock#9){+.+.}-{4:4}: [T79] __lock_acquire+0x535/0xc30 [T79] lock_acquire.part.0+0xb3/0x240 [T79] lock_acquire+0x60/0x140 [T79] __mutex_lock+0x1af/0x1c10 [T79] mutex_lock_nested+0x1b/0x30 [T79] cma_get_port+0xba/0x7d0 [rdma_cm] [T79] rdma_bind_addr_dst+0x598/0x9a0 [rdma_cm] [T79] cma_bind_addr+0x107/0x320 [rdma_cm] [T79] rdma_resolve_addr+0xa3/0x830 [rdma_cm] [T79] destroy_lease_table+0x12b/0x420 [ksmbd] [T79] ksmbd_NTtimeToUnix+0x3e/0x80 [ksmbd] [T79] ndr_encode_posix_acl+0x6e9/0xab0 [ksmbd] [T79] ndr_encode_v4_ntacl+0x53/0x870 [ksmbd] [T79] __sys_connect_file+0x131/0x1c0 [T79] __sys_connect+0x111/0x140 [T79] __x64_sys_connect+0x72/0xc0 [T79] x64_sys_call+0xe7d/0x26a0 [T79] do_syscall_64+0x93/0xff0 [T79] entry_SYSCALL_64_after_hwframe+0x76/0x7e [T79] -> #0 (sk_lock-AF_INET){+.+.}-{0:0}: [T79] check_prev_add+0xf3/0xcd0 [T79] validate_chain+0x466/0x590 [T79] __lock_acquire+0x535/0xc30 [T79] lock_acquire.part.0+0xb3/0x240 [T79] lock_acquire+0x60/0x140 [T79] lock_sock_nested+0x3b/0xf0 [T79] sock_set_reuseaddr+0x14/0x70 [T79] siw_create_listen+0x145/0x1540 [siw] [T79] iw_cm_listen+0x313/0x5b0 [iw_cm] [T79] cma_iw_listen+0x271/0x3c0 [rdma_cm] [T79] rdma_listen+0x3b1/0x740 [rdma_cm] [T79] cma_listen_on_dev+0x46a/0x750 [rdma_cm] [T79] rdma_listen+0x4b0/0x740 [rdma_cm] [T79] ksmbd_rdma_init+0x12b/0x270 [ksmbd] [T79] ksmbd_conn_transport_init+0x26/0x70 [ksmbd] [T79] server_ctrl_handle_work+0x1e5/0x280 [ksmbd] [T79] process_one_work+0x86c/0x1930 [T79] worker_thread+0x6f0/0x11f0 [T79] kthread+0x3ec/0x8b0 [T79] ret_from_fork+0x314/0x400 [T79] ret_from_fork_asm+0x1a/0x30 [T79] other info that might help us debug this: [T79] Possible unsafe locking scenario: [T79] CPU0 CPU1 [T79] ---- ---- [T79] lock(lock#9); [T79] lock(sk_lock-AF_INET); [T79] lock(lock#9); [T79] lock(sk_lock-AF_INET); [T79] *** DEADLOCK *** [T79] 5 locks held by kworker/2:0/79: [T79] #0: ffff88800120b158 ((wq_completion)events_long){+.+.}-{0:0}, at: process_one_work+0xfca/0x1930 [T79] #1: ffffc9000474fd00 ((work_completion)(&ctrl->ctrl_work)) {+.+.}-{0:0}, at: process_one_work+0x804/0x1930 [T79] #2: ffffffffc11307d0 (ctrl_lock){+.+.}-{4:4}, at: server_ctrl_handle_work+0x21/0x280 [ksmbd] [T79] #3: ffffffffc11347b0 (init_lock){+.+.}-{4:4}, at: ksmbd_conn_transport_init+0x18/0x70 [ksmbd] [T79] #4: ffffffffc10f7230 (lock#9){+.+.}-{4:4}, at: rdma_listen+0x3d2/0x740 [rdma_cm] [T79] stack backtrace: [T79] CPU: 2 UID: 0 PID: 79 Comm: kworker/2:0 Kdump: loaded Tainted: G OE 6.18.0-rc4-metze-kasan-lockdep.01+ #1 PREEMPT(voluntary) [T79] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE [T79] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [T79] Workqueue: events_long server_ctrl_handle_work [ksmbd] ... [T79] print_circular_bug+0xfd/0x130 [T79] check_noncircular+0x150/0x170 [T79] check_prev_add+0xf3/0xcd0 [T79] validate_chain+0x466/0x590 [T79] __lock_acquire+0x535/0xc30 [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] lock_acquire.part.0+0xb3/0x240 [T79] ? sock_set_reuseaddr+0x14/0x70 [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] ? __kasan_check_write+0x14/0x30 [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] ? apparmor_socket_post_create+0x180/0x700 [T79] lock_acquire+0x60/0x140 [T79] ? sock_set_reuseaddr+0x14/0x70 [T79] lock_sock_nested+0x3b/0xf0 [T79] ? sock_set_reuseaddr+0x14/0x70 [T79] sock_set_reuseaddr+0x14/0x70 [T79] siw_create_listen+0x145/0x1540 [siw] [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] ? local_clock_noinstr+0xe/0xd0 [T79] ? __pfx_siw_create_listen+0x10/0x10 [siw] [T79] ? trace_preempt_on+0x4c/0x130 [T79] ? __raw_spin_unlock_irqrestore+0x4a/0x90 [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] ? preempt_count_sub+0x52/0x80 [T79] iw_cm_listen+0x313/0x5b0 [iw_cm] [T79] cma_iw_listen+0x271/0x3c0 [rdma_cm] [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] rdma_listen+0x3b1/0x740 [rdma_cm] [T79] ? _raw_spin_unlock+0x2c/0x60 [T79] ? __pfx_rdma_listen+0x10/0x10 [rdma_cm] [T79] ? rdma_restrack_add+0x12c/0x630 [ib_core] [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] cma_listen_on_dev+0x46a/0x750 [rdma_cm] [T79] rdma_listen+0x4b0/0x740 [rdma_cm] [T79] ? __pfx_rdma_listen+0x10/0x10 [rdma_cm] [T79] ? cma_get_port+0x30d/0x7d0 [rdma_cm] [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] ? rdma_bind_addr_dst+0x598/0x9a0 [rdma_cm] [T79] ksmbd_rdma_init+0x12b/0x270 [ksmbd] [T79] ? __pfx_ksmbd_rdma_init+0x10/0x10 [ksmbd] [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] ? register_netdevice_notifier+0x1dc/0x240 [T79] ksmbd_conn_transport_init+0x26/0x70 [ksmbd] [T79] server_ctrl_handle_work+0x1e5/0x280 [ksmbd] [T79] process_one_work+0x86c/0x1930 [T79] ? __pfx_process_one_work+0x10/0x10 [T79] ? srso_alias_return_thunk+0x5/0xfbef5 [T79] ? assign_work+0x16f/0x280 [T79] worker_thread+0x6f0/0x11f0 I was not able to reproduce this as I was testing with various runs switching siw and rxe as well as IPPROTO_SMBDIRECT sockets, while the above stack used siw with the non IPPROTO_SMBDIRECT patches [1]. Even if this patch doesn't solve the above I think it's a good idea to reclassify the sockets used by siw, I also send patches for rxe to reclassify, as well as my IPPROTO_SMBDIRECT socket patches [1] will do it, this should minimize potential false positives. [1] https://git.samba.org/?p=metze/linux/wip.git;a=shortlog;h=refs/heads/master-ipproto-smbdirect Cc: Bernard Metzler Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: linux-rdma@vger.kernel.org Cc: netdev@vger.kernel.org Cc: linux-cifs@vger.kernel.org Signed-off-by: Stefan Metzmacher --- v2: - use CONFIG_DEBUG_LOCK_ALLOC (Bernard) - add a comment (Bernard) - AF_INET vs. AF_INET6 (Bernard) --- drivers/infiniband/sw/siw/siw_cm.c | 51 ++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/drivers/infiniband/sw/siw/siw_cm.c b/drivers/infiniband/sw/siw/siw_cm.c index 708b13993fdf..79dd44cd6bc3 100644 --- a/drivers/infiniband/sw/siw/siw_cm.c +++ b/drivers/infiniband/sw/siw/siw_cm.c @@ -39,6 +39,55 @@ static void siw_cm_llp_error_report(struct sock *s); static int siw_cm_upcall(struct siw_cep *cep, enum iw_cm_event_type reason, int status); + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +/* + * lockdep can detect false positive circular dependencies + * when there are user-space socket API users or in kernel + * users switching between a tcp and rdma transport. + * Maybe also switching between siw and rxe may cause + * problems as per default sockets are only classified + * by family and not by ip protocol. And there might + * be different locks used between the application + * and the low level sockets. + * + * Problems were seen with ksmbd.ko and cifs.ko, + * switching transports, use git blame to find + * more details. + */ +static struct lock_class_key siw_sk_key[2]; +static struct lock_class_key siw_slock_key[2]; +#endif /* CONFIG_DEBUG_LOCK_ALLOC */ + +static inline void siw_reclassify_socket(struct socket *sock) +{ +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct sock *sk = sock->sk; + + if (WARN_ON_ONCE(!sock_allow_reclassification(sk))) + return; + + switch (sk->sk_family) { + case AF_INET: + sock_lock_init_class_and_name(sk, + "slock-AF_INET-RDMA-SIW", + &siw_slock_key[0], + "sk_lock-AF_INET-RDMA-SIW", + &siw_sk_key[0]); + break; + case AF_INET6: + sock_lock_init_class_and_name(sk, + "slock-AF_INET6-RDMA-SIW", + &siw_slock_key[1], + "sk_lock-AF_INET6-RDMA-SIW", + &siw_sk_key[1]); + break; + default: + WARN_ON_ONCE(1); + } +#endif /* CONFIG_DEBUG_LOCK_ALLOC */ +} + static void siw_sk_assign_cm_upcalls(struct sock *sk) { struct siw_cep *cep = sk_to_cep(sk); @@ -1394,6 +1443,7 @@ int siw_connect(struct iw_cm_id *id, struct iw_cm_conn_param *params) rv = sock_create(v4 ? AF_INET : AF_INET6, SOCK_STREAM, IPPROTO_TCP, &s); if (rv < 0) goto error; + siw_reclassify_socket(s); /* * NOTE: For simplification, connect() is called in blocking @@ -1770,6 +1820,7 @@ int siw_create_listen(struct iw_cm_id *id, int backlog) rv = sock_create(addr_family, SOCK_STREAM, IPPROTO_TCP, &s); if (rv < 0) return rv; + siw_reclassify_socket(s); /* * Allow binding local port when still in TIME_WAIT from last close. -- 2.43.0