BUG: soft lockup in batadv_iv_send_outstanding_bat_ogm_packet

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f051383ef03b Linux 4.14.285
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15a648cc080000
kernel config: https://syzkaller.appspot.com/x/.config?x=a7875bb17064f2fb
dashboard link: https://syzkaller.appspot.com/bug?extid=de7cba59cdb5cf50845d
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14d4bee0080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14da65fff00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+de7cba...@syzkaller.appspotmail.com

batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-320)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-320)
batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (-320)
watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [kworker/u4:3:977]
Modules linked in:
irq event stamp: 192001
hardirqs last enabled at (192000): [<ffffffff812307db>] kvm_wait arch/x86/kernel/kvm.c:600 [inline]
hardirqs last enabled at (192000): [<ffffffff812307db>] kvm_wait+0x14b/0x240 arch/x86/kernel/kvm.c:580
hardirqs last disabled at (192001): [<ffffffff874018ae>] apic_timer_interrupt+0x8e/0xa0 arch/x86/entry/entry_64.S:793
softirqs last enabled at (182062): [<ffffffff86ecaa02>] spin_unlock_bh include/linux/spinlock.h:362 [inline]
softirqs last enabled at (182062): [<ffffffff86ecaa02>] batadv_forw_packet_steal+0x112/0x180 net/batman-adv/send.c:587
softirqs last disabled at (182072): [<ffffffff86eeda1a>] spin_lock_bh include/linux/spinlock.h:322 [inline]
softirqs last disabled at (182072): [<ffffffff86eeda1a>] batadv_tt_local_commit_changes+0x1a/0x30 net/batman-adv/translation-table.c:3947
CPU: 0 PID: 977 Comm: kworker/u4:3 Not tainted 4.14.285-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
task: ffff8880b382c000 task.stack: ffff8880b3830000
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
RSP: 0018:ffff8880b3837b70 EFLAGS: 000002c2 ORIG_RAX: ffffffffffffff10
RAX: 1ffffffff11e1344 RBX: ffff8880b2c0d298 RCX: 1ffff11016705924
RDX: dffffc0000000000 RSI: ffff8880b382c900 RDI: ffff8880b382c884
RBP: 0000000000000003 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000286
R13: dffffc0000000000 R14: ffff8880b2c0d299 R15: ffffed10174869f8
FS: 0000000000000000(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6ac6e9e028 CR3: 00000000a068b000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
kvm_wait arch/x86/kernel/kvm.c:600 [inline]
kvm_wait+0x179/0x240 arch/x86/kernel/kvm.c:580
pv_wait arch/x86/include/asm/paravirt.h:679 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:447 [inline]
__pv_queued_spin_lock_slowpath+0x722/0x910 kernel/locking/qspinlock.c:465
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:669 [inline]
queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:52 [inline]
queued_spin_lock include/asm-generic/qspinlock.h:90 [inline]
do_raw_spin_lock+0x178/0x200 kernel/locking/spinlock_debug.c:113
spin_lock_bh include/linux/spinlock.h:322 [inline]
batadv_tt_local_commit_changes+0x1a/0x30 net/batman-adv/translation-table.c:3947
batadv_iv_ogm_schedule_buff+0xcfb/0xf80 net/batman-adv/bat_iv_ogm.c:985
batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:1043 [inline]
batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:1036 [inline]
batadv_iv_send_outstanding_bat_ogm_packet+0x5a7/0x6f0 net/batman-adv/bat_iv_ogm.c:1861
process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 1e 5b fa e9 4f ff ff ff 48 89 ef e8 0d 1e 5b fa eb 93 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 0f 00 2d 54 ad 63 00 fb f4 <c3> 90 0f 1f 44 00 00 0f 00 2d 44 ad 63 00 f4 c3 90 90 41 55 41
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 5b pop %rbx
1: fa cli
2: e9 4f ff ff ff jmpq 0xffffff56
7: 48 89 ef mov %rbp,%rdi
a: e8 0d 1e 5b fa callq 0xfa5b1e1c
f: eb 93 jmp 0xffffffa4
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 90 nop
16: 90 nop
17: 90 nop
18: 90 nop
19: 90 nop
1a: 90 nop
1b: 90 nop
1c: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
21: 0f 00 2d 54 ad 63 00 verw 0x63ad54(%rip) # 0x63ad7c
28: fb sti
29: f4 hlt
* 2a: c3 retq <-- trapping instruction
2b: 90 nop
2c: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
31: 0f 00 2d 44 ad 63 00 verw 0x63ad44(%rip) # 0x63ad7c
38: f4 hlt
39: c3 retq
3a: 90 nop
3b: 90 nop
3c: 41 55 push %r13
3e: 41 rex.B


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