INFO: task hung in cleanup

INFO: task hung in cleanup_net
Status: auto-closed as invalid on 2019/10/18 21:44
Reported-by: syzbot+f3ac9e1a2fbff3875adb@syzkaller.appspotmail.com
First crash: 1199d, last: 831d

similar bugs (9):
Kernel	Title	Repro	Fix bisect	Count	Last	Reported	Patched	Status
upstream	INFO: task hung in cleanup_net (2)			2	826d	827d	0/22	closed as invalid on 2019/05/08 13:05
android-44	INFO: task hung in cleanup_net			10	781d	822d	0/2	auto-closed as invalid on 2019/10/25 08:38
upstream	INFO: task hung in cleanup_net			1	1331d	1319d	3/22	fixed on 2018/01/03 02:35
linux-4.19	INFO: task hung in cleanup_net			1	446d	446d	0/1	auto-closed as invalid on 2020/09/08 00:00
linux-4.14	INFO: task hung in cleanup_net	C	inconclusive	21	112d	839d	0/1	upstream: reported C repro on 2019/04/13 10:16
upstream	INFO: task hung in cleanup_net (3)			1	761d	761d	0/22	auto-closed as invalid on 2019/10/25 14:21
upstream	INFO: task hung in cleanup_net (4)			2	345d	350d	0/22	auto-closed as invalid on 2020/11/17 15:39
android-414	INFO: task hung in cleanup_net	C		45	699d	842d	0/1	public: reported C repro on 2019/04/11 00:00
android-49	INFO: task hung in cleanup_net (2)			1	614d	614d	0/3	auto-closed as invalid on 2020/03/23 02:35

Sample crash report:

audit: type=1400 audit(2000000079.296:1259): avc:  denied  { create } for  pid=31403 comm="syz-executor.0" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
INFO: task kworker/u4:25:21932 blocked for more than 140 seconds.
      Not tainted 4.9.170+ #45
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:25   D25256 21932      2 0x80000000
Workqueue: netns cleanup_net
 ffff8801c40297c0 ffff8801d2d30580 ffff8801db621000 ffff880187f1df00
 ffff8801db621018 ffff8801b23379a8 ffffffff8280185e 000060fe2460c518
 1ffff10036466f2c 0000000000000000 ffff8801db6218f0 1ffff10036466f24
Call Trace:
 [<00000000ef4404b8>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<0000000002c45c96>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<000000006120828e>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<000000006120828e>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<00000000e4dda4c9>] cleanup_net+0x131/0x8a0 net/core/net_namespace.c:440
 [<0000000075381d89>] process_one_work+0x88b/0x1600 kernel/workqueue.c:2114
 [<000000009e5fc9e2>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251
 [<0000000030693a1f>] kthread+0x278/0x310 kernel/kthread.c:211
 [<0000000088b1d35d>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
3 locks held by kworker/1:0/18:
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<00000000b488b54d>] process_one_work+0x790/0x1600 kernel/workqueue.c:2107
 #1:  ((addr_chk_work).work){+.+...}, at: [<00000000f7ac442d>] process_one_work+0x7ce/0x1600 kernel/workqueue.c:2111
 #2:  (rtnl_mutex){+.+.+.}, at: [<000000005a4f895e>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<000000007dbd2115>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline]
 #0:  (rcu_read_lock){......}, at: [<000000007dbd2115>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263
 #1:  (tasklist_lock){.+.+..}, at: [<000000008c987e8f>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339
2 locks held by getty/2024:
 #0:  (&tty->ldisc_sem){++++++}, at: [<000000008f49366d>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<00000000765675cb>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
3 locks held by kworker/u4:25/21932:
 #0:  ("%s""netns"){.+.+.+}, at: [<00000000b488b54d>] process_one_work+0x790/0x1600 kernel/workqueue.c:2107
 #1:  (net_cleanup_work){+.+.+.}, at: [<00000000f7ac442d>] process_one_work+0x7ce/0x1600 kernel/workqueue.c:2111
 #2:  (net_mutex){+.+.+.}, at: [<00000000e4dda4c9>] cleanup_net+0x131/0x8a0 net/core/net_namespace.c:440

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.170+ #45
 ffff8801d98d7cc8 ffffffff81b4fb21 0000000000000001 0000000000000000
 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b5adbc 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<00000000d8155db3>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000d8155db3>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<0000000086e32dd2>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<00000000209d5fc2>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<000000007fa18fd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<00000000e7306c50>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<00000000e7306c50>] check_hung_task kernel/hung_task.c:126 [inline]
 [<00000000e7306c50>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline]
 [<00000000e7306c50>] watchdog+0x670/0xaf0 kernel/hung_task.c:263
 [<0000000030693a1f>] kthread+0x278/0x310 kernel/kthread.c:211
 [<0000000088b1d35d>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 30813 Comm: syz-executor.4 Not tainted 4.9.170+ #45
task: 0000000066a1170c task.stack: 000000002b1a619c
RIP: 0010:[<ffffffff8120037f>] c [<00000000bbbbd8ad>] perf_trace_lock+0x1f/0x540 include/trace/events/lock.h:38
RSP: 0000:ffff88018bcd7aa0  EFLAGS: 00000087
RAX: 1ffff10038ccf383 RBX: ffff8801c6679c28 RCX: 1ffffffff063f7a4
RDX: dffffc0000000000 RSI: ffff8801d2d30680 RDI: ffffffff830c1dc0
RBP: ffff88018bcd7ab8 R08: 0000000000000001 R09: 0000000000006f64
R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff8149a1d4
R13: dffffc0000000000 R14: ffffffff830c1d40 R15: ffff88018bcd7a90
FS:  00007feac2ca4700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000004d1d3401c65 CR3: 000000017e888000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 dffffc0000000000c ffff8801d2d30680c ffffffff81200360c ffff88018bcd7b70c
 ffffffff8120da6ac 71109f33ab500c84c 0000000000000246c ffff880187f1df00c
 0000000000000000c 0000000000000000c 0000000000000001c ffff88018bcd7b70c
Call Trace:
 [<000000006e951ce3>] trace_lock_release include/trace/events/lock.h:57 [inline]
 [<000000006e951ce3>] lock_release+0x92a/0xc30 kernel/locking/lockdep.c:3777
 [<000000009fe6074a>] __might_fault mm/memory.c:4054 [inline]
 [<000000009fe6074a>] __might_fault+0x189/0x1d0 mm/memory.c:4039
 [<000000000ce465fd>] __copy_to_user arch/x86/include/asm/uaccess_64.h:181 [inline]
 [<000000000ce465fd>] save_xstate_epilog arch/x86/kernel/fpu/signal.c:88 [inline]
 [<000000000ce465fd>] copy_fpstate_to_sigframe+0x2e7/0x710 arch/x86/kernel/fpu/signal.c:201
 [<000000001285a2bb>] get_sigframe arch/x86/kernel/signal.c:282 [inline]
 [<000000001285a2bb>] __setup_rt_frame arch/x86/kernel/signal.c:463 [inline]
 [<000000001285a2bb>] setup_rt_frame arch/x86/kernel/signal.c:697 [inline]
 [<000000001285a2bb>] handle_signal arch/x86/kernel/signal.c:741 [inline]
 [<000000001285a2bb>] do_signal+0xf80/0x1920 arch/x86/kernel/signal.c:809
 [<000000004a7c37ae>] exit_to_usermode_loop+0x11c/0x160 arch/x86/entry/common.c:158
 [<00000000ec5ebf78>] prepare_exit_to_usermode+0x143/0x1b0 arch/x86/entry/common.c:194
 [<000000004f12fa7e>] retint_user+0x8/0x3c
Code: cfe cff cff c66 c0f c1f c84 c00 c00 c00 c00 c00 c48 cba c00 c00 c00 c00 c00 cfc cff cdf c55 c48 c89 ce5 c41 c57 c41 c56 c4c c8d c7d cd8 c49 c89 cfe c48 c83 cef c80 c41 c55 c<41> c54 c4c c8d ca5 c58 cff cff cff c49 cc1 cec c03 c53 c49 c8d c04 c14 c48 c81 cec c

Crashes (4):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report
ci-android-49-kasan-gce-root	2019/04/21 21:43	https://android.googlesource.com/kernel/common android-4.9	1ef64dae6217	b0e8efcb	.config	log	report
ci-android-49-kasan-gce-root	2019/04/19 06:42	https://android.googlesource.com/kernel/common android-4.9	5d68df32998c	b0e8efcb	.config	log	report
ci-android-49-kasan-gce-root	2019/01/04 03:41	https://android.googlesource.com/kernel/common android-4.9	043c92bd0517	7da23925	.config	log	report
ci-android-49-kasan-gce	2018/04/18 20:10	https://android.googlesource.com/kernel/common android-4.9	8683408f8e81	829f0234	.config	log	report