INFO: rcu detected stall in rtnl_newlink

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 20b3a3df Linux 4.19.134
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11438cdf100000
kernel config: https://syzkaller.appspot.com/x/.config?x=7c76c572c403b9ac
dashboard link: https://syzkaller.appspot.com/bug?extid=91af13ca9545b3f197ed
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15966740900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12e1dcdf100000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+91af13...@syzkaller.appspotmail.com

batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 1-...!: (10500 ticks this GP) idle=cca/1/0x4000000000000002 softirq=11988/11988 fqs=0
rcu: (t=10502 jiffies g=5361 q=4)
rcu: rcu_preempt kthread starved for 10503 jiffies! g5361 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt I29208 10 2 0x80000000
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
schedule_timeout+0x4cf/0xfe0 kernel/time/timer.c:1817
rcu_gp_kthread+0xdad/0x21c0 kernel/rcu/tree.c:2202
kthread+0x30b/0x410 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
NMI backtrace for cpu 1
CPU: 1 PID: 6456 Comm: syz-executor066 Not tainted 4.19.134-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2fe 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_single_cpu_backtrace include/linux/nmi.h:164 [inline]
rcu_dump_cpu_stacks+0x15f/0x19c kernel/rcu/tree.c:1340
print_cpu_stall kernel/rcu/tree.c:1478 [inline]
check_cpu_stall kernel/rcu/tree.c:1550 [inline]
__rcu_pending kernel/rcu/tree.c:3293 [inline]
rcu_pending kernel/rcu/tree.c:3336 [inline]
rcu_check_callbacks.cold+0x62d/0xe19 kernel/rcu/tree.c:2682
update_process_times+0x2a/0x70 kernel/time/timer.c:1649
tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:168
tick_sched_timer+0xfc/0x290 kernel/time/tick-sched.c:1278
__run_hrtimer kernel/time/hrtimer.c:1401 [inline]
__hrtimer_run_queues+0x3f6/0xe60 kernel/time/hrtimer.c:1463
hrtimer_interrupt+0x32a/0x930 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:894
</IRQ>
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:99 [inline]
RIP: 0010:__local_bh_enable_ip+0x18d/0x270 kernel/softirq.c:196
Code: 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 dd 00 00 00 48 83 3d a8 29 93 07 00 0f 84 8d 00 00 00 fb 66 0f 1f 44 00 00 <65> 8b 05 0c bc c2 7e 85 c0 74 7d 5b 5d 41 5c c3 80 3d 4a 4d 68 08
RSP: 0018:ffff8880a40f6bf8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11a4b6b RBX: 0000000000000201 RCX: 1ffff1101483bdd2
RDX: dffffc0000000000 RSI: ffff8880a41dee70 RDI: ffff8880a41dee44
RBP: ffffffff8721c6a8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a41de5c0
R13: ffff8880a0ff8698 R14: 0000000000000000 R15: dffffc0000000000
spin_unlock_bh include/linux/spinlock.h:374 [inline]
batadv_tt_local_purge+0x278/0x370 net/batman-adv/translation-table.c:1454
batadv_tt_local_resize_to_mtu+0x8e/0x130 net/batman-adv/translation-table.c:4205
batadv_hardif_activate_interface.part.0.cold+0x88/0x226 net/batman-adv/hard-interface.c:664
batadv_hardif_activate_interface net/batman-adv/hard-interface.c:825 [inline]
batadv_hardif_enable_interface+0xadf/0xba0 net/batman-adv/hard-interface.c:817
batadv_softif_slave_add+0x8a/0x100 net/batman-adv/soft-interface.c:898
do_set_master+0x1c8/0x220 net/core/rtnetlink.c:2321
do_setlink+0x7ec/0x3540 net/core/rtnetlink.c:2455
rtnl_newlink+0xda0/0x15a0 net/core/rtnetlink.c:3077
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4777
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:632
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
__sys_sendmsg net/socket.c:2153 [inline]
__do_sys_sendmsg net/socket.c:2162 [inline]
__se_sys_sendmsg net/socket.c:2160 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4437d9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 fb 0f fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc1855cd68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004437d9
RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000004
RBP: 00007ffc1855cd70 R08: 0000000001bbbbbb R09: 0000000001bbbbbb
R10: 0000000001bbbbbb R11: 0000000000000246 R12: 00007ffc1855cd80
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
net_ratelimit: 6439 callbacks suppressed
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
net_ratelimit: 6727 callbacks suppressed
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-224)


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