BUG: soft lockup in neigh_timer_handler

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=111d1ada700000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=e8b9b40f2d14d6af88f0
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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+e8b9b4...@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [syz-executor.2:8856]
Modules linked in:
irq event stamp: 3396551
hardirqs last enabled at (3396550): [<ffffffff81003ce4>] trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (3396551): [<ffffffff81003d00>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last enabled at (16902): [<ffffffff88400678>] __do_softirq+0x678/0x980 kernel/softirq.c:318
softirqs last disabled at (17121): [<ffffffff813927d5>] invoke_softirq kernel/softirq.c:372 [inline]
softirqs last disabled at (17121): [<ffffffff813927d5>] irq_exit+0x215/0x260 kernel/softirq.c:412
CPU: 1 PID: 8856 Comm: syz-executor.2 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__ipv6_dev_get_saddr+0x2b3/0x5f0 net/ipv6/addrconf.c:1606
Code: fc ff df 48 89 f8 48 c1 e8 03 80 3c 08 00 0f 85 c8 02 00 00 48 b9 00 00 00 00 00 fc ff df 48 8b 44 24 08 48 8b 9b 40 01 00 00 <48> c1 e8 03 80 3c 08 00 48 8d ab c0 fe ff ff 0f 85 8e 02 00 00 48
RSP: 0000:ffff8880ba107548 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff8880ba107640 RBX: ffff8880a1177b80 RCX: dffffc0000000000
RDX: 0000000000000100 RSI: ffffffff8704057b RDI: ffff888035b571c0
RBP: 00000000fffffff2 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: 0000000000000002
R13: ffff8880ba107638 R14: ffff8880a06c0040 R15: ffff8880ba1075f8
FS: 0000555555d37400(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e022000 CR3: 000000009f43b000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
ipv6_dev_get_saddr+0x56c/0xc20 net/ipv6/addrconf.c:1774
ip6_route_get_saddr include/net/ip6_route.h:124 [inline]
ip6_dst_lookup_tail+0x1233/0x19b0 net/ipv6/ip6_output.c:997
icmpv6_route_lookup+0x9e/0x4e0 net/ipv6/icmp.c:343
icmp6_send+0x1592/0x22c0 net/ipv6/icmp.c:555
__icmpv6_send include/linux/icmpv6.h:28 [inline]
icmpv6_send include/linux/icmpv6.h:49 [inline]
ip6_link_failure+0x2d/0x4f0 net/ipv6/route.c:2297
dst_link_failure include/net/dst.h:438 [inline]
ndisc_error_report+0xc7/0x190 net/ipv6/ndisc.c:695
neigh_invalidate+0x22c/0x540 net/core/neighbour.c:900
neigh_timer_handler+0x9b2/0xc70 net/core/neighbour.c:986
call_timer_fn+0x177/0x700 kernel/time/timer.c:1338
expire_timers+0x243/0x4e0 kernel/time/timer.c:1375
__run_timers kernel/time/timer.c:1696 [inline]
run_timer_softirq+0x21c/0x670 kernel/time/timer.c:1709
__do_softirq+0x265/0x980 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x215/0x260 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x136/0x550 arch/x86/kernel/apic/apic.c:1098
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894
</IRQ>
RIP: 0033:0x7f32a0032081
Code: c7 44 24 08 00 00 00 00 41 89 ed 4c 8d 25 97 8f 15 00 eb 24 0f 1f 44 00 00 4c 89 ff e8 d8 18 ff ff 41 08 c5 0f 85 f7 01 00 00 <41> 83 c6 01 44 39 73 04 0f 86 b7 00 00 00 48 8b 04 24 44 89 f7 48
RSP: 002b:00007ffd303d7a00 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 000000000283f250 RBX: 00007f32a01970c8 RCX: 0000001b2dd20000
RDX: 000000000283f250 RSI: 0000001b2dd210bc RDI: 0000000009f34895
RBP: 000000000283f250 R08: 0000000000001250 R09: 000000000283f254
R10: 00007ffd303d7bd0 R11: 0000000000000246 R12: 00007f32a018b000
R13: 0000000000000001 R14: 00000000000000a2 R15: ffffffff83772075
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
----------------
Code disassembly (best guess), 2 bytes skipped:
0: df 48 89 fisttps -0x77(%rax)
3: f8 clc
4: 48 c1 e8 03 shr $0x3,%rax
8: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1)
c: 0f 85 c8 02 00 00 jne 0x2da
12: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
19: fc ff df
1c: 48 8b 44 24 08 mov 0x8(%rsp),%rax
21: 48 8b 9b 40 01 00 00 mov 0x140(%rbx),%rbx
* 28: 48 c1 e8 03 shr $0x3,%rax <-- trapping instruction
2c: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1)
30: 48 8d ab c0 fe ff ff lea -0x140(%rbx),%rbp
37: 0f 85 8e 02 00 00 jne 0x2cb
3d: 48 rex.W


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[syzbot]

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