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[109.66.7.121]) by smtp.gmail.com with ESMTPSA id p6sm3821823wrt.3.2020.05.05.09.10.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 09:10:24 -0700 (PDT) Date: Tue, 5 May 2020 12:10:22 -0400 From: "Michael S. Tsirkin" To: Thomas Gleixner Cc: netdev@vger.kernel.org, Jason Wang Subject: Re: [BUG] Inconsistent lock state in virtnet poll Message-ID: <20200505120352-mutt-send-email-mst@kernel.org> References: <87lfm6oa7b.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87lfm6oa7b.fsf@nanos.tec.linutronix.de> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, May 05, 2020 at 02:08:56PM +0200, Thomas Gleixner wrote: > > The following lockdep splat happens reproducibly on 5.7-rc4 > > Thanks, > > tglx > > ================================ > WARNING: inconsistent lock state > 5.7.0-rc4+ #79 Not tainted > -------------------------------- > inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. > ip/356 [HC0[0]:SC1[1]:HE1:SE0] takes: > f3ee4cd8 (&syncp->seq#2){+.?.}-{0:0}, at: net_rx_action+0xfb/0x390 > {SOFTIRQ-ON-W} state was registered at: > lock_acquire+0x82/0x300 > try_fill_recv+0x39f/0x590 Weird. Where does try_fill_recv acquire any locks? > virtnet_open+0xe0/0x180 > __dev_open+0xbe/0x160 > __dev_change_flags+0x152/0x1b0 > dev_change_flags+0x23/0x60 > do_setlink+0x814/0xa30 > __rtnl_newlink+0x583/0x8e0 > rtnl_newlink+0x36/0x60 > rtnetlink_rcv_msg+0x139/0x470 > netlink_rcv_skb+0x6a/0xe0 > rtnetlink_rcv+0xd/0x10 > netlink_unicast+0x175/0x250 > netlink_sendmsg+0x263/0x440 > sock_sendmsg+0x5c/0x60 > ____sys_sendmsg+0x182/0x1d0 > ___sys_sendmsg+0x59/0x90 > __sys_sendmsg+0x39/0x80 > __ia32_sys_socketcall+0x2d2/0x330 > do_fast_syscall_32+0x82/0x340 > entry_SYSENTER_32+0xaa/0x102 > irq event stamp: 2276 > hardirqs last enabled at (2276): [] net_rx_action+0x7e/0x390 > hardirqs last disabled at (2275): [] net_rx_action+0x58/0x390 > softirqs last enabled at (2272): [] virtnet_napi_enable+0xe/0x50 > softirqs last disabled at (2273): [] call_on_stack+0x40/0x50 > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock(&syncp->seq#2); > > lock(&syncp->seq#2); > > *** DEADLOCK *** > > 1 lock held by ip/356: > #0: c20a4a38 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x118/0x470 > > stack backtrace: > CPU: 2 PID: 356 Comm: ip Not tainted 5.7.0-rc4+ #79 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 > Call Trace: > > dump_stack+0x6e/0x9e > print_usage_bug.cold+0x15a/0x162 > mark_lock+0x58d/0x6e0 > ? check_usage_backwards+0x180/0x180 > __lock_acquire+0xdd7/0x24f0 > ? select_task_rq_fair+0xbb/0xfe0 > ? __lock_acquire+0x35f/0x24f0 > ? __lock_acquire+0x35f/0x24f0 > ? __lock_acquire+0x35f/0x24f0 > lock_acquire+0x82/0x300 > ? net_rx_action+0xfb/0x390 > ? find_held_lock+0x24/0x80 > ? lock_release+0x8a/0x260 > ? virtnet_poll+0xd0/0x3d9 > virtnet_poll+0x1d3/0x3d9 > ? net_rx_action+0xfb/0x390 > ? trace_hardirqs_on+0x4a/0xf0 > net_rx_action+0xfb/0x390 > ? __do_softirq+0x84/0x3ca > ? virtnet_napi_enable+0xe/0x50 > __do_softirq+0xb1/0x3ca > ? virtnet_napi_enable+0xe/0x50 > ? __irqentry_text_end+0x8/0x8 > call_on_stack+0x40/0x50 > > ? do_softirq.part.0+0x4e/0x50 > ? __local_bh_enable_ip+0xd1/0xe0 > ? virtnet_napi_enable+0x41/0x50 > ? virtnet_open+0x7f/0x180 > ? __dev_open+0xbe/0x160 > ? __dev_change_flags+0x152/0x1b0 > ? dev_change_flags+0x23/0x60 > ? do_setlink+0x814/0xa30 > ? __lock_acquire+0x35f/0x24f0 > ? __nla_parse+0x1c/0x30 > ? __rtnl_newlink+0x583/0x8e0 > ? lock_acquire+0x82/0x300 > ? handle_mm_fault+0x6e6/0xa10 > ? find_held_lock+0x24/0x80 > ? __lock_acquire+0x35f/0x24f0 > ? lock_acquire+0x82/0x300 > ? __lock_acquire+0x35f/0x24f0 > ? rtnl_newlink+0x23/0x60 > ? rcu_read_lock_sched_held+0x3f/0x70 > ? kmem_cache_alloc_trace+0x235/0x260 > ? rtnl_newlink+0x36/0x60 > ? __rtnl_newlink+0x8e0/0x8e0 > ? rtnetlink_rcv_msg+0x139/0x470 > ? netlink_deliver_tap+0x81/0x3a0 > ? find_held_lock+0x24/0x80 > ? rtnl_bridge_getlink+0x240/0x240 > ? netlink_rcv_skb+0x6a/0xe0 > ? rtnl_bridge_getlink+0x240/0x240 > ? rtnetlink_rcv+0xd/0x10 > ? netlink_unicast+0x175/0x250 > ? netlink_sendmsg+0x263/0x440 > ? netlink_unicast+0x250/0x250 > ? sock_sendmsg+0x5c/0x60 > ? ____sys_sendmsg+0x182/0x1d0 > ? ___sys_sendmsg+0x59/0x90 > ? lock_acquire+0x82/0x300 > ? __might_fault+0x39/0x80 > ? __sys_sendmsg+0x39/0x80 > ? __ia32_sys_socketcall+0x2d2/0x330 > ? do_fast_syscall_32+0x82/0x340 > ? entry_SYSENTER_32+0xaa/0x102