From: Chris Leech cleech@redhat.com
[ Upstream commit 841aee4d75f18fdfb53935080b03de0c65e9b92c ]
Put NVMe/TCP sockets in their own class to avoid some lockdep warnings. Sockets created by nvme-tcp are not exposed to user-space, and will not trigger certain code paths that the general socket API exposes.
Lockdep complains about a circular dependency between the socket and filesystem locks, because setsockopt can trigger a page fault with a socket lock held, but nvme-tcp sends requests on the socket while file system locks are held.
====================================================== WARNING: possible circular locking dependency detected 5.15.0-rc3 #1 Not tainted ------------------------------------------------------ fio/1496 is trying to acquire lock: (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendpage+0x23/0x80
but task is already holding lock: (&xfs_dir_ilock_class/5){+.+.}-{3:3}, at: xfs_ilock+0xcf/0x290 [xfs]
which lock already depends on the new lock.
other info that might help us debug this:
chain exists of: sk_lock-AF_INET --> sb_internal --> &xfs_dir_ilock_class/5
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(&xfs_dir_ilock_class/5); lock(sb_internal); lock(&xfs_dir_ilock_class/5); lock(sk_lock-AF_INET);
*** DEADLOCK ***
6 locks held by fio/1496: #0: (sb_writers#13){.+.+}-{0:0}, at: path_openat+0x9fc/0xa20 #1: (&inode->i_sb->s_type->i_mutex_dir_key){++++}-{3:3}, at: path_openat+0x296/0xa20 #2: (sb_internal){.+.+}-{0:0}, at: xfs_trans_alloc_icreate+0x41/0xd0 [xfs] #3: (&xfs_dir_ilock_class/5){+.+.}-{3:3}, at: xfs_ilock+0xcf/0x290 [xfs] #4: (hctx->srcu){....}-{0:0}, at: hctx_lock+0x51/0xd0 #5: (&queue->send_mutex){+.+.}-{3:3}, at: nvme_tcp_queue_rq+0x33e/0x380 [nvme_tcp]
This annotation lets lockdep analyze nvme-tcp controlled sockets independently of what the user-space sockets API does.
Link: https://lore.kernel.org/linux-nvme/CAHj4cs9MDYLJ+q+2_GXUK9HxFizv2pxUryUR0toX...
Signed-off-by: Chris Leech cleech@redhat.com Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvme/host/tcp.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+)
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c index 65e00c64a588..d66e2de044e0 100644 --- a/drivers/nvme/host/tcp.c +++ b/drivers/nvme/host/tcp.c @@ -30,6 +30,44 @@ static int so_priority; module_param(so_priority, int, 0644); MODULE_PARM_DESC(so_priority, "nvme tcp socket optimize priority");
+#ifdef CONFIG_DEBUG_LOCK_ALLOC +/* lockdep can detect a circular dependency of the form + * sk_lock -> mmap_lock (page fault) -> fs locks -> sk_lock + * because dependencies are tracked for both nvme-tcp and user contexts. Using + * a separate class prevents lockdep from conflating nvme-tcp socket use with + * user-space socket API use. + */ +static struct lock_class_key nvme_tcp_sk_key[2]; +static struct lock_class_key nvme_tcp_slock_key[2]; + +static void nvme_tcp_reclassify_socket(struct socket *sock) +{ + 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-NVME", + &nvme_tcp_slock_key[0], + "sk_lock-AF_INET-NVME", + &nvme_tcp_sk_key[0]); + break; + case AF_INET6: + sock_lock_init_class_and_name(sk, "slock-AF_INET6-NVME", + &nvme_tcp_slock_key[1], + "sk_lock-AF_INET6-NVME", + &nvme_tcp_sk_key[1]); + break; + default: + WARN_ON_ONCE(1); + } +} +#else +static void nvme_tcp_reclassify_socket(struct socket *sock) { } +#endif + enum nvme_tcp_send_state { NVME_TCP_SEND_CMD_PDU = 0, NVME_TCP_SEND_H2C_PDU, @@ -1469,6 +1507,8 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl, goto err_destroy_mutex; }
+ nvme_tcp_reclassify_socket(queue->sock); + /* Single syn retry */ tcp_sock_set_syncnt(queue->sock->sk, 1);