Hello,

syzbot found the following crash on:

HEAD commit: 6b8a7946 Merge tag 'for_linus' of git://git.kernel.org/pub.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=175973cee00000 kernel config: https://syzkaller.appspot.com/x/.config?x=4737c15fc47048f2 dashboard link: https://syzkaller.appspot.com/bug?extid=1a41521b3198c9e15c2f 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+1a41521b3198c9e15c2f@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-....: (1 GPs behind) idle=e6a/1/0x4000000000000002 softirq=14144/14145 fqs=5200 (t=10500 jiffies g=14865 q=1519) NMI backtrace for cpu 1 CPU: 1 PID: 10088 Comm: syz-executor.4 Not tainted 5.4.0-rc8-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+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x183/0x1cf kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] rcu_pending kernel/rcu/tree.c:2795 [inline] rcu_sched_clock_irq.cold+0x4fd/0xc12 kernel/rcu/tree.c:2244 update_process_times+0x2d/0x70 kernel/time/timer.c:1726 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1299 __run_hrtimer kernel/time/hrtimer.c:1514 [inline] __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1576 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1638 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 </IRQ> RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:756 [inline] RIP: 0010:console_unlock+0xbc7/0xf10 kernel/printk/printk.c:2481 Code: f3 88 48 c1 e8 03 42 80 3c 30 00 0f 85 e4 02 00 00 48 83 3d 4a 8f 96 07 00 0f 84 91 01 00 00 e8 3f c2 16 00 48 8b 7d 98 57 9d <0f> 1f 44 00 00 e9 6d ff ff ff e8 2a c2 16 00 48 8b 7d 08 c7 05 dc RSP: 0018:ffff888057b17528 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 0000000000040000 RBX: 0000000000000200 RCX: ffffc9000e7a9000 RDX: 0000000000040000 RSI: ffffffff815c94e1 RDI: 0000000000000246 RBP: ffff888057b175b0 R08: 1ffffffff14f0134 R09: fffffbfff14f0135 R10: fffffbfff14f0134 R11: ffffffff8a7809a7 R12: 0000000000000000 R13: ffffffff843e6780 R14: dffffc0000000000 R15: ffffffff895db0f0 vprintk_emit+0x2a0/0x700 kernel/printk/printk.c:1996 vprintk_default+0x28/0x30 kernel/printk/printk.c:2023 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 printk+0xba/0xed kernel/printk/printk.c:2056 batadv_tt_local_resize_to_mtu.cold+0x18/0x1e net/batman-adv/translation-table.c:4202 batadv_update_min_mtu net/batman-adv/hard-interface.c:626 [inline] batadv_hard_if_event+0x64f/0xfa0 net/batman-adv/hard-interface.c:1056 notifier_call_chain+0xc2/0x230 kernel/notifier.c:95 __raw_notifier_call_chain kernel/notifier.c:396 [inline] raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1668 call_netdevice_notifiers_mtu net/core/dev.c:1717 [inline] dev_set_mtu_ext+0x354/0x5a0 net/core/dev.c:8014 dev_set_mtu+0xa5/0x130 net/core/dev.c:8035 dev_ifsioc+0x357/0xa00 net/core/dev_ioctl.c:244 dev_ioctl+0x1b8/0xc70 net/core/dev_ioctl.c:489 sock_do_ioctl+0x1b7/0x2f0 net/socket.c:1061 sock_ioctl+0x3ed/0x790 net/socket.c:1189 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a639 Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f8b5149ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a639 RDX: 0000000020000180 RSI: 0000000000008922 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8b5149b6d4 R13: 00000000004c6652 R14: 00000000004dbae8 R15: 00000000ffffffff

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