From mboxrd@z Thu Jan 1 00:00:00 1970 From: Valdis Kletnieks Subject: linux-next 20141208 - net/sched/sch_fq_codel.c:97 suspicious RCU Date: Tue, 09 Dec 2014 12:51:40 -0500 Message-ID: <6468.1418147500@turing-police.cc.vt.edu> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1418147500_3854P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: John Fastabend , Eric Dumazet , "David S. Miller" Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org --==_Exmh_1418147500_3854P Content-Type: text/plain; charset=us-ascii Spotted this in dmesg while investigating why my wireless broke sometime between next-20141201 and next-20141208. Probably not related, as wireless has been broken on several boot attempts of -1208, but this has popped only once.... Looks like the fault of commit 46e5da40aec256155cfedee96dd21a75da941f2c Author: John Fastabend Date: Fri Sep 12 20:04:52 2014 -0700 net: qdisc: use rcu prefix and silence sparse warnings but I freely admit that exhausts my RCU debugging skills. :) [ 104.743212] =============================== [ 104.743214] [ INFO: suspicious RCU usage. ] [ 104.743218] 3.18.0-next-20141208 #27 Tainted: G OE [ 104.743219] ------------------------------- [ 104.743224] net/sched/sch_fq_codel.c:97 suspicious rcu_dereference_check() usage! [ 104.743227] other info that might help us debug this: [ 104.743231] rcu_scheduler_active = 1, debug_locks = 1 [ 104.743236] 4 locks held by unbound/1873: [ 104.743239] #0: (rcu_read_lock_bh){......}, at: [] rcu_lock_acquire+0x0/0x22 [ 104.743257] #1: (rcu_read_lock_bh){......}, at: [] rcu_lock_acquire+0x0/0x22 [ 104.743274] #2: (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.....}, at: [] __dev_queue_xmit+0x32a/0x66a [ 104.743292] #3: (&qdisc_tx_lock){+.-...}, at: [] __dev_queue_xmit+0x333/0x66a [ 104.743302] stack backtrace: [ 104.743307] CPU: 2 PID: 1873 Comm: unbound Tainted: G OE 3.18.0-next-20141208 #27 [ 104.743309] Hardware name: Dell Inc. Latitude E6530/07Y85M, BIOS A15 06/20/2014 [ 104.743312] 0000000000000001 ffff8800b9f3f978 ffffffff8a6ba925 ffff880223bac210 [ 104.743317] 0000000000000001 ffff8800b9f3f9a8 ffffffff8a07f124 ffff8800b9ce4e00 [ 104.743323] ffff880223fea600 0000000000000000 ffff8800c6e2c000 ffff8800b9f3f9f8 [ 104.743329] Call Trace: [ 104.743336] [] dump_stack+0x50/0xa8 [ 104.743343] [] lockdep_rcu_suspicious+0xea/0xf3 [ 104.743348] [] fq_codel_enqueue+0x79/0x21c [ 104.743353] [] ? _raw_spin_lock+0x37/0x3f [ 104.743357] [] __dev_queue_xmit+0x43b/0x66a [ 104.743362] [] dev_queue_xmit+0xb/0xd [ 104.743367] [] ip_finish_output2+0x42b/0x46c [ 104.743371] [] ip_finish_output+0x13c/0x144 [ 104.743376] [] ip_output+0x4c/0x70 [ 104.743381] [] ip_local_out_sk+0x54/0x5f [ 104.743385] [] ip_send_skb+0x12/0x37 [ 104.743390] [] udp_send_skb+0x176/0x1db [ 104.743394] [] udp_sendmsg+0x63e/0x87c [ 104.743398] [] ? skb_set_owner_w+0x56/0x56 [ 104.743404] [] ? __rcu_read_unlock+0xf5/0xfd [ 104.743408] [] ? rcu_read_unlock+0x3e/0x5d [ 104.743413] [] inet_sendmsg+0x3d/0x66 [ 104.743419] [] __sock_sendmsg_nosec+0x25/0x27 [ 104.743422] [] sock_sendmsg+0x5a/0x7b [ 104.743429] [] ? might_fault+0xae/0xb0 [ 104.743433] [] ? audit_sockaddr+0x2b/0x44 [ 104.743437] [] SYSC_sendto+0x119/0x15c [ 104.743443] [] ? do_audit_syscall_entry+0xb8/0xc7 [ 104.743447] [] SyS_sendto+0x9/0xb [ 104.743453] [] system_call_fastpath+0x12/0x17 --==_Exmh_1418147500_3854P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Exmh version 2.5 07/13/2001 iQIVAwUBVIc2rAdmEQWDXROgAQJTjhAAoWASTftlDRqz0z9qzju12nrRDwgmtOQg OmqLq/isuXXnHd9RWcB2zalmfhwWgkPzYKZJfc6NEHz5p59jNS2AhC89KlS55Wj2 16rArpiIOquYn3qoQNBlZvjRqTr1SvjWZex6h/IumZNDxqa7EnyC3k7oEetDpFAO sK2lar2HdTlFbFgN9gA7EWjmdNjLEfqO2OrXTFLqgt4pvnCwPrYljkAjWS+1tQLw jxEubNZyXq94OJkbbwejtMtJ2pwyNaIISvxG0vZAZ8rRJmS7OXoak7hHfwAQpRCY /pxcWjOrwoRi6+bmsoAuCLd9+xkp5QjNnO16Mjk7WhRxRIY7SwomKZMAdyrItXqp AKkTETmvEZofJ6/jdvK+cJ3388hD1lAikKh8QvvU6+rlZLU6L0G5NLZ9bDKEqFRa o5k0EskwRpKoUZC1uc4Imh5aZYVeUIUp01ASz6//VcqeAmwvHdc0RxeQhj6ZYkBZ 8p0YZf27e526n73DMPTeCbfTO6j5EfVZBj0X6YDzIfVILTR6NkDFAApx1Nc7p/D1 wdEpN2GJaiJ3intYsBQ4YhPfE44B+UHn4IUjgP5rxNr28o40MCyx52tAgNtLsUgs 9xpFXOWNHXAakkKT1LcE3My0s0fbkFX2G7nUnbXfgB+lXd1STe+OFJyBlRpMcrzd U8p/s0EbsaY= =43L/ -----END PGP SIGNATURE----- --==_Exmh_1418147500_3854P--