Message-ID: <CACT4Y+bG0oGm5kagr1pPCxYiPw2pngnFeu2uKOtN2U05mQCRvA@mail.gmail.com>
Date:   Tue, 26 Mar 2019 09:58:59 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Salil Mehta <salil.mehta@...wei.com>
Cc:     syzbot <syzbot+e350b81e95a6a214da8a@...kaller.appspotmail.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-hams@...r.kernel.org" <linux-hams@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "ralf@...ux-mips.org" <ralf@...ux-mips.org>,
        "syzkaller-bugs@...glegroups.com" <syzkaller-bugs@...glegroups.com>
Subject: Re: inconsistent lock state in ax25_std_heartbeat_expiry

On Tue, Mar 26, 2019 at 9:38 AM Salil Mehta <salil.mehta@...wei.com> wrote:
>
> Not reproducible on our setup either. Thanks for reporting though.
> We will keep an eye!

Hi Salil,

Shouldn't these lockdep reports be self-explanatory without
reproduction? The report contains stacks for both SOFTIRQ-ON-W and
IN-SOFTIRQ-W contexts. So provided the lockdep report is not badly
broken in itself, that should be enough explanation of the problem. Or
I am missing something?


> > -----Original Message-----
> > From: netdev-owner@...r.kernel.org [mailto:netdev-
> > owner@...r.kernel.org] On Behalf Of syzbot
> > Sent: Monday, March 25, 2019 6:55 PM
> > To: davem@...emloft.net; linux-hams@...r.kernel.org; linux-
> > kernel@...r.kernel.org; netdev@...r.kernel.org; ralf@...ux-mips.org;
> > syzkaller-bugs@...glegroups.com
> > Subject: inconsistent lock state in ax25_std_heartbeat_expiry
> >
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    5f543a54 net: hns3: fix for not calculating tx bd num
> > corr..
> > git tree:       net
> > console output:
> > https://syzkaller.appspot.com/x/log.txt?x=10c8652b200000
> > kernel config:
> > https://syzkaller.appspot.com/x/.config?x=f05902bca21d8935
> > dashboard link:
> > https://syzkaller.appspot.com/bug?extid=e350b81e95a6a214da8a
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> >
> > Unfortunately, I don't have any reproducer for this crash yet.
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the
> > commit:
> > Reported-by: syzbot+e350b81e95a6a214da8a@...kaller.appspotmail.com
> >
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:66:56:21:74:14:df, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > ================================
> > WARNING: inconsistent lock state
> > 5.0.0+ #134 Not tainted
> > --------------------------------
> > inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
> > ksoftirqd/1/16 [HC0[0]:SC1[1]:HE1:SE0] takes:
> > 000000008282a7d4 (slock-AF_AX25){+.?.}, at: spin_lock
> > include/linux/spinlock.h:329 [inline]
> > 000000008282a7d4 (slock-AF_AX25){+.?.}, at:
> > ax25_std_heartbeat_expiry+0x5d/0x3e0 net/ax25/ax25_std_timer.c:37
> > {SOFTIRQ-ON-W} state was registered at:
> >    lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
> >    __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
> >    _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
> >    spin_lock include/linux/spinlock.h:329 [inline]
> >    ax25_rt_autobind+0x3ca/0x720 net/ax25/ax25_route.c:432
> >    ax25_connect.cold+0x30/0xa4 net/ax25/af_ax25.c:1224
> >    __sys_connect+0x266/0x330 net/socket.c:1808
> >    __do_sys_connect net/socket.c:1819 [inline]
> >    __se_sys_connect net/socket.c:1816 [inline]
> >    __x64_sys_connect+0x73/0xb0 net/socket.c:1816
> >    do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
> >    entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > irq event stamp: 296868110
> > hardirqs last  enabled at (296868110): [<ffffffff870f1ad8>]
> > __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
> > hardirqs last  enabled at (296868110): [<ffffffff870f1ad8>]
> > _raw_spin_unlock_irq+0x28/0x90 kernel/locking/spinlock.c:192
> > hardirqs last disabled at (296868109): [<ffffffff870f1c4a>]
> > __raw_spin_lock_irq include/linux/spinlock_api_smp.h:126 [inline]
> > hardirqs last disabled at (296868109): [<ffffffff870f1c4a>]
> > _raw_spin_lock_irq+0x3a/0x80 kernel/locking/spinlock.c:160
> > softirqs last  enabled at (296868102): [<ffffffff87400662>]
> > __do_softirq+0x662/0x95a kernel/softirq.c:320
> > softirqs last disabled at (296868107): [<ffffffff8144c8ae>]
> > run_ksoftirqd
> > kernel/softirq.c:655 [inline]
> > softirqs last disabled at (296868107): [<ffffffff8144c8ae>]
> > run_ksoftirqd+0x8e/0x110 kernel/softirq.c:647
> >
> > other info that might help us debug this:
> >   Possible unsafe locking scenario:
> >
> >         CPU0
> >         ----
> >    lock(slock-AF_AX25);
> >    <Interrupt>
> >      lock(slock-AF_AX25);
> >
> >   *** DEADLOCK ***
> >
> > 1 lock held by ksoftirqd/1/16:
> >   #0: 00000000654921c3 ((&ax25->timer)){+.-.}, at: lockdep_copy_map
> > include/linux/lockdep.h:170 [inline]
> >   #0: 00000000654921c3 ((&ax25->timer)){+.-.}, at:
> > call_timer_fn+0xda/0x720
> > kernel/time/timer.c:1315
> >
> > stack backtrace:
> > CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.0.0+ #134
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > Google 01/01/2011
> > Call Trace:
> >   __dump_stack lib/dump_stack.c:77 [inline]
> >   dump_stack+0x172/0x1f0 lib/dump_stack.c:113
> >   print_usage_bug.cold+0x330/0x42a kernel/locking/lockdep.c:2839
> >   valid_state kernel/locking/lockdep.c:2852 [inline]
> >   mark_lock_irq kernel/locking/lockdep.c:3046 [inline]
> >   mark_lock+0xd58/0x1380 kernel/locking/lockdep.c:3421
> >   mark_irqflags kernel/locking/lockdep.c:3299 [inline]
> >   __lock_acquire+0x1654/0x3fb0 kernel/locking/lockdep.c:3653
> >   lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
> >   __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
> >   _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
> >   spin_lock include/linux/spinlock.h:329 [inline]
> >   ax25_std_heartbeat_expiry+0x5d/0x3e0 net/ax25/ax25_std_timer.c:37
> >   ax25_heartbeat_expiry+0xf3/0x120 net/ax25/ax25_timer.c:141
> >   call_timer_fn+0x190/0x720 kernel/time/timer.c:1325
> >   expire_timers kernel/time/timer.c:1362 [inline]
> >   __run_timers kernel/time/timer.c:1681 [inline]
> >   __run_timers kernel/time/timer.c:1649 [inline]
> >   run_timer_softirq+0x652/0x1700 kernel/time/timer.c:1694
> >   __do_softirq+0x266/0x95a kernel/softirq.c:293
> >   run_ksoftirqd kernel/softirq.c:655 [inline]
> >   run_ksoftirqd+0x8e/0x110 kernel/softirq.c:647
> >   smpboot_thread_fn+0x6ab/0xa10 kernel/smpboot.c:164
> >   kthread+0x357/0x430 kernel/kthread.c:253
> >   ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
> > net_ratelimit: 21613 callbacks suppressed
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:66:56:21:74:14:df, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:66:56:21:74:14:df, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > net_ratelimit: 16407 callbacks suppressed
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:66:56:21:74:14:df, vlan:0)
> > bridge0: received packet on bridge_slave_0 with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
> > bridge0: received packet on veth0_to_bridge with own address as source
> > address (addr:66:56:21:74:14:df, vlan:0)
> >
> >
> > ---
> > This bug is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@...glegroups.com.
> >
> > syzbot will keep track of this bug report. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
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