INFO: rcu detected stall in cleanup_net (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 811218ec Linux 4.19.172
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=113e693cd00000
kernel config: https://syzkaller.appspot.com/x/.config?x=c1cb1d27398c8808
dashboard link: https://syzkaller.appspot.com/bug?extid=88f1a8081aa8a52c3c52

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+88f1a8...@syzkaller.appspotmail.com

UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2020/09/19 18:44 (1000)
UDF-fs: error (device loop1): udf_process_sequence: Primary Volume Descriptor not found!
UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2020/09/19 18:44 (1000)
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 1-...!: (1 GPs behind) idle=b1a/1/0x4000000000000002 softirq=28520/28535 fqs=3
rcu: (t=10502 jiffies g=25897 q=388)
rcu: rcu_preempt kthread starved for 10497 jiffies! g25897 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt I29760 10 2 0x80000000
Call Trace:
context_switch syzkaller/managers/linux-4-19/kernel/kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 syzkaller/managers/linux-4-19/kernel/kernel/sched/core.c:3517
schedule+0x8d/0x1b0 syzkaller/managers/linux-4-19/kernel/kernel/sched/core.c:3561
schedule_timeout+0x4cf/0xfe0 syzkaller/managers/linux-4-19/kernel/kernel/time/timer.c:1818
rcu_gp_kthread+0xdad/0x21c0 syzkaller/managers/linux-4-19/kernel/kernel/rcu/tree.c:2202
kthread+0x33f/0x460 syzkaller/managers/linux-4-19/kernel/kernel/kthread.c:259
ret_from_fork+0x24/0x30 syzkaller/managers/linux-4-19/kernel/arch/x86/entry/entry_64.S:415
NMI backtrace for cpu 1
CPU: 1 PID: 7 Comm: kworker/u4:0 Not tainted 4.19.172-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
<IRQ>
__dump_stack syzkaller/managers/linux-4-19/kernel/lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef syzkaller/managers/linux-4-19/kernel/lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa2 syzkaller/managers/linux-4-19/kernel/lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1a6/0x1f0 syzkaller/managers/linux-4-19/kernel/lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace syzkaller/managers/linux-4-19/kernel/./include/linux/nmi.h:164 [inline]
rcu_dump_cpu_stacks+0x15f/0x19c syzkaller/managers/linux-4-19/kernel/kernel/rcu/tree.c:1340
print_cpu_stall syzkaller/managers/linux-4-19/kernel/kernel/rcu/tree.c:1478 [inline]
check_cpu_stall syzkaller/managers/linux-4-19/kernel/kernel/rcu/tree.c:1550 [inline]
__rcu_pending syzkaller/managers/linux-4-19/kernel/kernel/rcu/tree.c:3293 [inline]
rcu_pending syzkaller/managers/linux-4-19/kernel/kernel/rcu/tree.c:3336 [inline]
rcu_check_callbacks.cold+0x62d/0xe19 syzkaller/managers/linux-4-19/kernel/kernel/rcu/tree.c:2682
update_process_times+0x2a/0x70 syzkaller/managers/linux-4-19/kernel/kernel/time/timer.c:1650
tick_sched_handle+0x9b/0x180 syzkaller/managers/linux-4-19/kernel/kernel/time/tick-sched.c:168
tick_sched_timer+0xfc/0x290 syzkaller/managers/linux-4-19/kernel/kernel/time/tick-sched.c:1278
__run_hrtimer syzkaller/managers/linux-4-19/kernel/kernel/time/hrtimer.c:1401 [inline]
__hrtimer_run_queues+0x3f6/0xe60 syzkaller/managers/linux-4-19/kernel/kernel/time/hrtimer.c:1463
hrtimer_interrupt+0x32a/0x930 syzkaller/managers/linux-4-19/kernel/kernel/time/hrtimer.c:1521
local_apic_timer_interrupt syzkaller/managers/linux-4-19/kernel/arch/x86/kernel/apic/apic.c:1067 [inline]
smp_apic_timer_interrupt+0x10c/0x550 syzkaller/managers/linux-4-19/kernel/arch/x86/kernel/apic/apic.c:1092
apic_timer_interrupt+0xf/0x20 syzkaller/managers/linux-4-19/kernel/arch/x86/entry/entry_64.S:894
</IRQ>
RIP: 0010:__read_once_size syzkaller/managers/linux-4-19/kernel/./include/linux/compiler.h:207 [inline]
RIP: 0010:radix_tree_load_root syzkaller/managers/linux-4-19/kernel/lib/radix-tree.c:603 [inline]
RIP: 0010:__radix_tree_lookup+0x21/0x370 syzkaller/managers/linux-4-19/kernel/lib/radix-tree.c:1040
Code: e9 0a fe ff ff 0f 1f 40 00 41 57 48 8d 47 40 41 56 49 be 00 00 00 00 00 fc ff df 41 55 41 54 55 53 48 83 ec 40 48 89 44 24 38 <48> 89 44 24 30 48 c1 e8 03 4c 01 f0 48 89 7c 24 10 48 89 74 24 08
RSP: 0018:ffff8880b5a57b68 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: ffff88809ca49080 RBX: 00000000a9316c9b RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffffa9316c9b RDI: ffff88809ca49040
RBP: ffff88809ca49040 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: ffff88809ca49090
R13: ffffed1013949219 R14: dffffc0000000000 R15: 0000000000000788
tipc_topsrv_stop syzkaller/managers/linux-4-19/kernel/net/tipc/topsrv.c:698 [inline]
tipc_topsrv_exit_net+0x25e/0x5c0 syzkaller/managers/linux-4-19/kernel/net/tipc/topsrv.c:722
ops_exit_list+0xa5/0x150 syzkaller/managers/linux-4-19/kernel/net/core/net_namespace.c:153
cleanup_net+0x3b4/0x8b0 syzkaller/managers/linux-4-19/kernel/net/core/net_namespace.c:553
process_one_work+0x864/0x1570 syzkaller/managers/linux-4-19/kernel/kernel/workqueue.c:2155
worker_thread+0x64c/0x1130 syzkaller/managers/linux-4-19/kernel/kernel/workqueue.c:2298
kthread+0x33f/0x460 syzkaller/managers/linux-4-19/kernel/kernel/kthread.c:259
ret_from_fork+0x24/0x30 syzkaller/managers/linux-4-19/kernel/arch/x86/entry/entry_64.S:415


---
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 syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

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