INFO: task hung in cleanup_net

[syzbot]

Hello,

syzkaller hit the following crash on
e40fd8d6b4d9f59b160faa1736f78fc07533ff37
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

Unfortunately, I don't have any reproducer for this bug yet.


sctp: sctp_transport_update_pmtu: Reported pmtu 508 too low, using default
minimum of 512
sctp: sctp_transport_update_pmtu: Reported pmtu 508 too low, using default
minimum of 512
sctp: sctp_transport_update_pmtu: Reported pmtu 508 too low, using default
minimum of 512
INFO: task kworker/u4:11:3785 blocked for more than 120 seconds.
Not tainted 4.15.0-rc2-next-20171207+ #61
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:11 D16448 3785 2 0x80000000
Workqueue: netns cleanup_net
Call Trace:
context_switch kernel/sched/core.c:2800 [inline]
__schedule+0x8eb/0x2060 kernel/sched/core.c:3376
schedule+0xf5/0x430 kernel/sched/core.c:3435
schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3493
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
cleanup_net+0x24c/0xb60 net/core/net_namespace.c:453
process_one_work+0xbfd/0x1bc0 kernel/workqueue.c:2113
worker_thread+0x223/0x1990 kernel/workqueue.c:2247
kthread+0x37a/0x440 kernel/kthread.c:238
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524

Showing all locks held in the system:
2 locks held by khungtaskd/672:
#0: (rcu_read_lock){....}, at: [<00000000b9bef8ab>]
check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
#0: (rcu_read_lock){....}, at: [<00000000b9bef8ab>] watchdog+0x1c5/0xd60
kernel/hung_task.c:249
#1: (tasklist_lock){.+.+}, at: [<000000006d6acf8b>]
debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554
1 lock held by rsyslogd/2970:
#0: (&f->f_pos_lock){+.+.}, at: [<000000001cede688>]
__fdget_pos+0x131/0x1a0 fs/file.c:765
2 locks held by getty/3052:
#0: (&tty->ldisc_sem){++++}, at: [<000000004e0245ba>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ff863b18>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3053:
#0: (&tty->ldisc_sem){++++}, at: [<000000004e0245ba>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ff863b18>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3054:
#0: (&tty->ldisc_sem){++++}, at: [<000000004e0245ba>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ff863b18>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3055:
#0: (&tty->ldisc_sem){++++}, at: [<000000004e0245ba>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ff863b18>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3056:
#0: (&tty->ldisc_sem){++++}, at: [<000000004e0245ba>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ff863b18>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3057:
#0: (&tty->ldisc_sem){++++}, at: [<000000004e0245ba>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ff863b18>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3058:
#0: (&tty->ldisc_sem){++++}, at: [<000000004e0245ba>]
ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
#1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000ff863b18>]
n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
1 lock held by syz-executor2/3320:
#0: (rtnl_mutex){+.+.}, at: [<0000000063c47ced>] rtnl_lock+0x17/0x20
net/core/rtnetlink.c:74
4 locks held by kworker/u4:11/3785:
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<0000000087d81703>]
__write_once_size include/linux/compiler.h:212 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<0000000087d81703>]
atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<0000000087d81703>]
atomic_long_set include/asm-generic/atomic-long.h:57 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<0000000087d81703>]
set_work_data kernel/workqueue.c:619 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<0000000087d81703>]
set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ((wq_completion)"%s""netns"){+.+.}, at: [<0000000087d81703>]
process_one_work+0xad4/0x1bc0 kernel/workqueue.c:2084
#1: (net_cleanup_work){+.+.}, at: [<000000008a817b5c>]
process_one_work+0xb2f/0x1bc0 kernel/workqueue.c:2088
#2: (net_mutex){+.+.}, at: [<0000000079150fd8>] cleanup_net+0x247/0xb60
net/core/net_namespace.c:450
#3: (rtnl_mutex){+.+.}, at: [<0000000063c47ced>] rtnl_lock+0x17/0x20
net/core/rtnetlink.c:74
3 locks held by kworker/0:6/14978:
#0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at:
[<0000000087d81703>] __write_once_size include/linux/compiler.h:212 [inline]
#0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at:
[<0000000087d81703>] atomic64_set arch/x86/include/asm/atomic64_64.h:34
[inline]
#0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at:
[<0000000087d81703>] atomic_long_set include/asm-generic/atomic-long.h:57
[inline]
#0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at:
[<0000000087d81703>] set_work_data kernel/workqueue.c:619 [inline]
#0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at:
[<0000000087d81703>] set_work_pool_and_clear_pending kernel/workqueue.c:646
[inline]
#0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at:
[<0000000087d81703>] process_one_work+0xad4/0x1bc0 kernel/workqueue.c:2084
#1: ((addr_chk_work).work){+.+.}, at: [<000000008a817b5c>]
process_one_work+0xb2f/0x1bc0 kernel/workqueue.c:2088
#2: (rtnl_mutex){+.+.}, at: [<0000000063c47ced>] rtnl_lock+0x17/0x20
net/core/rtnetlink.c:74
1 lock held by syz-executor2/15852:
#0: (rtnl_mutex){+.+.}, at: [<0000000063c47ced>] rtnl_lock+0x17/0x20
net/core/rtnetlink.c:74
1 lock held by syz-executor7/15958:
#0: (rtnl_mutex){+.+.}, at: [<0000000063c47ced>] rtnl_lock+0x17/0x20
net/core/rtnetlink.c:74
1 lock held by syz-executor7/15961:
#0: (rtnl_mutex){+.+.}, at: [<0000000063c47ced>] rtnl_lock+0x17/0x20
net/core/rtnetlink.c:74

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 672 Comm: khungtaskd Not tainted 4.15.0-rc2-next-20171207+ #61
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
check_hung_task kernel/hung_task.c:132 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
watchdog+0x90c/0xd60 kernel/hung_task.c:249
kthread+0x37a/0x440 kernel/kthread.c:238
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 15938 Comm: syz-executor7 Not tainted 4.15.0-rc2-next-20171207+
#61
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:inb arch/x86/include/asm/io.h:348 [inline]
RIP: 0010:io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:434
RSP: 0018:ffff8801c1c173e8 EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffc90001c88000 RDI: ffffffff880fa9c0
RBP: ffff8801c1c173f8 R08: 0000000000000002 R09: 000000000000000c
R10: 0000000000000000 R11: ffffffff87896d20 R12: ffffffff880fa980
R13: 0000000000000020 R14: fffffbfff101f577 R15: fffffbfff101f53a
FS: 00007f1ef8fad700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbea91b6000 CR3: 00000001d0aaa000 CR4: 00000000001406f0
DR0: 0000000020001000 DR1: 0000000020001000 DR2: 0000000020001020
DR3: 0000000020000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
serial_in drivers/tty/serial/8250/8250.h:111 [inline]
wait_for_xmitr+0x93/0x1e0 drivers/tty/serial/8250/8250_port.c:2033
serial8250_console_putchar+0x1f/0x60
drivers/tty/serial/8250/8250_port.c:3170
uart_console_write+0xac/0xe0 drivers/tty/serial/serial_core.c:1858
serial8250_console_write+0x647/0xa20
drivers/tty/serial/8250/8250_port.c:3236
univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:590
call_console_drivers kernel/printk/printk.c:1574 [inline]
console_unlock+0x788/0xd70 kernel/printk/printk.c:2233
vprintk_emit+0x4ad/0x590 kernel/printk/printk.c:1757
vprintk_default+0x28/0x30 kernel/printk/printk.c:1796
vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
printk+0xaa/0xca kernel/printk/printk.c:1829
__dev_set_promiscuity+0x2a4/0x630 net/core/dev.c:6609
__dev_change_flags+0x559/0x990 net/core/dev.c:6826
dev_change_flags+0x88/0x140 net/core/dev.c:6886
dev_ifsioc+0x60d/0x9b0 net/core/dev_ioctl.c:257
dev_ioctl+0x2c2/0xf90 net/core/dev_ioctl.c:566
sock_do_ioctl+0x94/0xb0 net/socket.c:971
sock_ioctl+0x2c2/0x440 net/socket.c:1061
vfs_ioctl fs/ioctl.c:46 [inline]
do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a39
RSP: 002b:00007f1ef8facc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1ef8fad700 RCX: 0000000000452a39
RDX: 00000000208a3fe0 RSI: 0000000000008914 RDI: 0000000000000019
RBP: 0000000000a6f880 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a6f7ff R14: 00007f1ef8fad9c0 R15: 0000000000000002
Code: 24 d9 00 00 00 49 8d 7c 24 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa
48 c1 ea 03 d3 e3 80 3c 02 00 75 17 41 03 5c 24 40 89 da ec <5b> 0f b6 c0
41 5c 5d c3 e8 88 ad 18 ff eb c2 e8 e1 ad 18 ff eb


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzk...@googlegroups.com.
Please credit me with: Reported-by: syzbot <syzk...@googlegroups.com>

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[Dmitry Vyukov]

On Tue, Dec 19, 2017 at 1:33 PM, syzbot
<bot+b17f10c8a8c693b407...@syzkaller.appspotmail.com>
wrote:

This looks like +rtnetlink issue.

> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzk...@googlegroups.com.
> Please credit me with: Reported-by: syzbot <syzk...@googlegroups.com>
>
> syzbot will keep track of this bug report.
> Once a fix for this bug is merged into any tree, reply to this email with:
> #syz fix: exact-commit-title
> To mark this as a duplicate of another syzbot report, please reply with:
> #syz dup: exact-subject-of-another-report
> If it's a one-off invalid bug report, please reply with:
> #syz invalid
> Note: if the crash happens again, it will cause creation of a new bug
> report.
> Note: all commands must start from beginning of the line in the email body.
>

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[David Ahern]

Perhaps related to / fixed by: http://patchwork.ozlabs.org/patch/850957/

[Dmitry Vyukov]

If you think so, let's tell syzbot about it:

#syz fix: net: Fix double free and memory corruption in get_net_ns_by_id()