INFO: task hung in cleanup_net

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 033c4ea4 Linux 4.19.122
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=165f910c100000
kernel config: https://syzkaller.appspot.com/x/.config?x=7f9e43a505369285
dashboard link: https://syzkaller.appspot.com/bug?extid=7edaa13e19c00a55aee5
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+7edaa1...@syzkaller.appspotmail.com

netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
IPVS: ftp: loaded support on port[0] = 21
INFO: task kworker/u4:1:19422 blocked for more than 140 seconds.
Not tainted 4.19.122-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:1 D25872 19422 2 0x80000000
Workqueue: netns cleanup_net
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3559
__rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
rwsem_down_read_failed+0x21b/0x3c0 kernel/locking/rwsem-xadd.c:309
call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94
__down_read arch/x86/include/asm/rwsem.h:83 [inline]
down_read+0x45/0xb0 kernel/locking/rwsem.c:26
cleanup_net+0xa8/0x850 net/core/net_namespace.c:520
process_one_work+0x91f/0x1640 kernel/workqueue.c:2155
worker_thread+0x96/0xe20 kernel/workqueue.c:2298
kthread+0x34a/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
INFO: task syz-executor.0:958 blocked for more than 140 seconds.
Not tainted 4.19.122-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D28416 958 6436 0x00000004
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3559
__rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:589 [inline]
rwsem_down_write_failed+0x774/0xc30 kernel/locking/rwsem-xadd.c:618
call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:117
__down_write arch/x86/include/asm/rwsem.h:142 [inline]
down_write+0x4f/0x90 kernel/locking/rwsem.c:72
unregister_netdevice_notifier+0x75/0x320 net/core/dev.c:1712
raw_release+0x53/0x6c0 net/can/raw.c:358
__sock_release+0xcd/0x2a0 net/socket.c:579
sock_close+0x15/0x20 net/socket.c:1140
__fput+0x2cd/0x890 fs/file_table.c:278
task_work_run+0x13f/0x1b0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x25a/0x2b0 arch/x86/entry/common.c:167
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x416421
Code: Bad RIP value.
RSP: 002b:00007ffe499eddd0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000416421
RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000791558 R09: 0000000000000000
R10: 00007ffe499edeb0 R11: 0000000000000293 R12: 0000000000791560
R13: 0000000000000000 R14: ffffffffffffffff R15: 000000000078bf0c

Showing all locks held in the system:
1 lock held by khungtaskd/1079:
#0: 0000000012542bb0 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by systemd-journal/3678:
2 locks held by syz-fuzzer/6416:
2 locks held by kworker/u4:0/26425:
3 locks held by kworker/1:1/27902:
#0: 000000004e6be00a ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline]
#0: 000000004e6be00a ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: 000000004e6be00a ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline]
#0: 000000004e6be00a ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline]
#0: 000000004e6be00a ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline]
#0: 000000004e6be00a ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
#0: 000000004e6be00a ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: process_one_work+0x81a/0x1640 kernel/workqueue.c:2126
#1: 00000000cdc2fc4f ((addr_chk_work).work){+.+.}, at: process_one_work+0x84e/0x1640 kernel/workqueue.c:2130
#2: 000000002808175e (rtnl_mutex){+.+.}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4475
3 locks held by kworker/u4:1/19422:
#0: 00000000c57d1346 ((wq_completion)"%s""netns"){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline]
#0: 00000000c57d1346 ((wq_completion)"%s""netns"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: 00000000c57d1346 ((wq_completion)"%s""netns"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline]
#0: 00000000c57d1346 ((wq_completion)"%s""netns"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline]
#0: 00000000c57d1346 ((wq_completion)"%s""netns"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline]
#0: 00000000c57d1346 ((wq_completion)"%s""netns"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
#0: 00000000c57d1346 ((wq_completion)"%s""netns"){+.+.}, at: process_one_work+0x81a/0x1640 kernel/workqueue.c:2126
#1: 00000000c9201e94 (net_cleanup_work){+.+.}, at: process_one_work+0x84e/0x1640 kernel/workqueue.c:2130
#2: 0000000079866836 (pernet_ops_rwsem){++++}, at: cleanup_net+0xa8/0x850 net/core/net_namespace.c:520
1 lock held by syz-executor.5/20314:
1 lock held by syz-executor.5/30214:
2 locks held by syz-executor.0/958:
#0: 0000000010554542 (&sb->s_type->i_mutex_key#13){+.+.}, at: inode_lock include/linux/fs.h:748 [inline]
#0: 0000000010554542 (&sb->s_type->i_mutex_key#13){+.+.}, at: __sock_release+0x86/0x2a0 net/socket.c:578
#1: 0000000079866836 (pernet_ops_rwsem){++++}, at: unregister_netdevice_notifier+0x75/0x320 net/core/dev.c:1712
3 locks held by syz-executor.0/976:

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

NMI backtrace for cpu 1
CPU: 1 PID: 1079 Comm: khungtaskd Not tainted 4.19.122-syzkaller #0
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+0x188/0x20d lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
watchdog+0x962/0xe40 kernel/hung_task.c:287
kthread+0x34a/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 976 Comm: syz-executor.0 Not tainted 4.19.122-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:match_held_lock+0x20/0x4f0 kernel/locking/lockdep.c:3476
Code: e9 1b ff ff ff 0f 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 41 56 41 55 41 54 55 53 48 89 fb 48 83 c7 10 48 89 fa 48 83 ec 08 <48> c1 ea 03 80 3c 02 00 0f 85 e2 03 00 00 48 39 73 10 0f 84 f9 01
RSP: 0000:ffff8880ae607d80 EFLAGS: 00000082
RAX: dffffc0000000000 RBX: ffff88804bfbcfc0 RCX: ffffffff81595beb
RDX: ffff88804bfbcfd0 RSI: ffff8880ae625b98 RDI: ffff88804bfbcfd0
RBP: ffff8880ae625b98 R08: ffff88804bfbc6c0 R09: ffffffff8ad01008
R10: ffffffff8ad01010 R11: 0000000000000001 R12: ffffed10097f79e8
R13: ffff88804bfbcf48 R14: ffff88804bfbcfc0 R15: 0000000000000003
FS: 00007f8b9ed90700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002262d7c8 CR3: 00000001f91b7000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
__lock_is_held+0xad/0x140 kernel/locking/lockdep.c:3727
lock_is_held_type+0x10d/0x210 kernel/locking/lockdep.c:3945
lock_is_held include/linux/lockdep.h:344 [inline]
__run_hrtimer kernel/time/hrtimer.c:1369 [inline]
__hrtimer_run_queues+0x4d6/0xd50 kernel/time/hrtimer.c:1463
hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1521
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline]
smp_apic_timer_interrupt+0x10c/0x550 arch/x86/kernel/apic/apic.c:1092
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline]
RIP: 0010:qlink_free mm/kasan/quarantine.c:150 [inline]
RIP: 0010:qlist_free_all+0xfc/0x140 mm/kasan/quarantine.c:166
Code: 50 08 48 8d 4a ff 83 e2 01 48 0f 45 c1 4c 8b 70 18 e9 40 ff ff ff e8 63 1a cf ff 48 83 3d 63 94 34 07 00 74 36 4c 89 ff 57 9d <0f> 1f 44 00 00 4d 85 e4 75 9e 49 c7 45 08 00 00 00 00 49 c7 45 00
RSP: 0000:ffff888203f875d0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: ffff88800e2a48c0 RCX: 1ffff110097f79f2
RDX: 0000000000000000 RSI: ffff88804bfbcf98 RDI: 0000000000000282
RBP: 0000000000000000 R08: ffff88804bfbc6c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88800e2a47e0
R13: ffff888203f87608 R14: ffff88812c2f7240 R15: 0000000000000282
quarantine_reduce+0x164/0x1a0 mm/kasan/quarantine.c:259
kasan_kmalloc+0x95/0xe0 mm/kasan/kasan.c:538
__do_kmalloc mm/slab.c:3727 [inline]
__kmalloc_track_caller+0x153/0x770 mm/slab.c:3742
kstrdup+0x36/0x70 mm/util.c:56
kstrdup_const+0x53/0x80 mm/util.c:77
__kernfs_new_node+0x9b/0x680 fs/kernfs/dir.c:629
kernfs_new_node+0x92/0x120 fs/kernfs/dir.c:693
kernfs_create_dir_ns+0x48/0x150 fs/kernfs/dir.c:1019
sysfs_create_dir_ns+0x127/0x280 fs/sysfs/dir.c:58
create_dir lib/kobject.c:88 [inline]
kobject_add_internal+0x29d/0x8c0 lib/kobject.c:247
kobject_add_varg lib/kobject.c:382 [inline]
kobject_init_and_add+0x101/0x160 lib/kobject.c:453
netdev_queue_add_kobject net/core/net-sysfs.c:1481 [inline]
netdev_queue_update_kobjects+0x11e/0x3c0 net/core/net-sysfs.c:1509
register_queue_kobjects net/core/net-sysfs.c:1551 [inline]
netdev_register_kobject+0x29b/0x3b0 net/core/net-sysfs.c:1769
register_netdevice+0x7f7/0xf50 net/core/dev.c:8710
register_netdev+0x2d/0x50 net/core/dev.c:8832
loopback_net_init+0x73/0x160 drivers/net/loopback.c:218
ops_init+0xaf/0x410 net/core/net_namespace.c:129
setup_net+0x2c2/0x6f0 net/core/net_namespace.c:315
copy_net_ns+0x1d9/0x331 net/core/net_namespace.c:438
create_new_namespaces+0x3fb/0x7c0 kernel/nsproxy.c:107
unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:206
ksys_unshare+0x439/0x8d0 kernel/fork.c:2530
__do_sys_unshare kernel/fork.c:2598 [inline]
__se_sys_unshare kernel/fork.c:2596 [inline]
__x64_sys_unshare+0x2d/0x40 kernel/fork.c:2596
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f8b9ed8fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 0000000000509f60 RCX: 000000000045c829
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000c4e R14: 00000000004ce7bd R15: 00007f8b9ed906d4


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.