Subject: [syzbot] INFO: task can't die in msleep

From: syzbot <[email-masked]>
Date: Mon, 29 Mar 2021 09:34:21 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    b4f20b70 Add linux-next specific files for 20210325
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17e6bb06d00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c7d6f0d01f04bcd8
dashboard link: https://syzkaller.appspot.com/bug?extid=3a9c5d436cf1afce2cd6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=105da362d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17a6978ad00000

The issue was bisected to:

commit 766b0515d5bec4b780750773ed3009b148df8c0a
Author: Jakub Kicinski <[email-masked]>
Date:   Wed Jan 6 18:40:07 2021 +0000

    net: make sure devices go through netdev_wait_all_refs

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=124939aad00000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=114939aad00000
console output: https://syzkaller.appspot.com/x/log.txt?x=164939aad00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]
Fixes: 766b0515d5be ("net: make sure devices go through netdev_wait_all_refs")

INFO: task syz-executor638:25158 can't die for more than 143 seconds.
task:syz-executor638 state:D stack:26512 pid:25158 ppid:  8420 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4329 [inline]
 __schedule+0x911/0x2160 kernel/sched/core.c:5079
 schedule+0xcf/0x270 kernel/sched/core.c:5158
 schedule_timeout+0x14a/0x250 kernel/time/timer.c:1878
 schedule_timeout_uninterruptible kernel/time/timer.c:1912 [inline]
 msleep+0xa4/0xf0 kernel/time/timer.c:2032
 netdev_wait_allrefs net/core/dev.c:10457 [inline]
 netdev_run_todo+0x9e8/0xe10 net/core/dev.c:10538
 register_netdev+0x35/0x50 net/core/dev.c:10381
 sit_init_net+0x3a4/0xac0 net/ipv6/sit.c:1917
 ops_init+0xaf/0x470 net/core/net_namespace.c:140
 setup_net+0x40f/0xa30 net/core/net_namespace.c:333
 copy_net_ns+0x31e/0x760 net/core/net_namespace.c:474
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 copy_namespaces+0x385/0x440 kernel/nsproxy.c:178
 copy_process+0x2bfe/0x71b0 kernel/fork.c:2111
 kernel_clone+0xe7/0xab0 kernel/fork.c:2501
 __do_sys_clone+0xc8/0x110 kernel/fork.c:2618
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x44da69
RSP: 002b:00007fd03f038318 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00000000004cb4a8 RCX: 000000000044da69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000200
RBP: 00000000004cb4a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cb4ac
R13: 00007ffc9cc08d4f R14: 00007fd03f038400 R15: 0000000000022000

Showing all locks held in the system:
5 locks held by kworker/u4:8/422:
1 lock held by khungtaskd/1638:
 #0: ffffffff8bf75360 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6333
2 locks held by in:imklog/8122:
 #0: ffff888014d1eff0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:961
 #1: ffff8880b9d35218 (&rq->lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1329 [inline]
 #1: ffff8880b9d35218 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x21c/0x2160 kernel/sched/core.c:4996
3 locks held by kworker/0:0/8498:
 #0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff888010864d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
 #1: ffffc90001a0fda8 (fqdir_free_work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
 #2: ffffffff8bf7e470 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x44/0x430 kernel/rcu/tree.c:4018
2 locks held by kworker/1:12/10637:
 #0: ffff888010866538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff888010866538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff888010866538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff888010866538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff888010866538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff888010866538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
 #1: ffffc9000b3afda8 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
2 locks held by syz-executor638/25158:
 #0: ffffffff8d674910 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x2fa/0x760 net/core/net_namespace.c:470
 #1: ffffffff8d6883e8 (rtnl_mutex){+.+.}-{3:3}, at: netdev_wait_allrefs net/core/dev.c:10428 [inline]
 #1: ffffffff8d6883e8 (rtnl_mutex){+.+.}-{3:3}, at: netdev_run_todo+0xa13/0xe10 net/core/dev.c:10538
1 lock held by syz-executor638/1031:
 #0: ffffffff8d674910 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x2fa/0x760 net/core/net_namespace.c:470
2 locks held by syz-executor638/1086:
 #0: ffffffff8d674910 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x2fa/0x760 net/core/net_namespace.c:470
 #1: ffffffff8d6883e8 (rtnl_mutex){+.+.}-{3:3}, at: cangw_pernet_exit+0xe/0x20 net/can/gw.c:1241
2 locks held by syz-executor638/1091:
 #0: ffffffff8d674910 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x2fa/0x760 net/core/net_namespace.c:470
 #1: ffffffff8d6883e8 (rtnl_mutex){+.+.}-{3:3}, at: tc_action_net_exit include/net/act_api.h:147 [inline]
 #1: ffffffff8d6883e8 (rtnl_mutex){+.+.}-{3:3}, at: gate_exit_net+0x22/0x360 net/sched/act_gate.c:624
2 locks held by syz-executor638/1113:
 #0: ffffffff8d674910 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x2fa/0x760 net/core/net_namespace.c:470
 #1: ffffffff8d6883e8 (rtnl_mutex){+.+.}-{3:3}, at: fib6_rules_net_exit+0xe/0x50 net/ipv6/fib6_rules.c:496
2 locks held by syz-executor638/1198:
 #0: ffffffff8d674910 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x2fa/0x760 net/core/net_namespace.c:470
 #1: ffffffff8d6883e8 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_create_pnetids_list net/smc/smc_pnet.c:799 [inline]
 #1: ffffffff8d6883e8 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_net_init+0x245/0x400 net/smc/smc_pnet.c:868

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

---
This report 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 [email-masked].

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches