============================================
WARNING: possible recursive locking detected
6.1.147-syzkaller #0 Not tainted
--------------------------------------------
syz.3.916/8516 is trying to acquire lock:
ffff8880596d3218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff8880596d3218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3925 [inline]
ffff8880596d3218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x208f/0x3760 net/core/dev.c:4300
but task is already holding lock:
ffff888063998258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
ffff888063998258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
ffff888063998258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline]
ffff888063998258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x129a/0x3760 net/core/dev.c:4300
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
*** DEADLOCK ***
May be due to missing lock nesting notation
9 locks held by syz.3.916/8516:
#0: ffffc900001e0bc0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc1/0x670 kernel/time/timer.c:1501
#1: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#1: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#1: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: ndisc_send_skb+0x1f2/0x1510 net/ipv6/ndisc.c:484
#2: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#2: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#2: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x593/0x1590 net/ipv6/ip6_output.c:123
#3: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#3: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
#3: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257
#4: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#4: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#4: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: bond_start_xmit+0xfe/0x1b90 drivers/net/bonding/bond_main.c:5523
#5: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#5: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
#5: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257
#6: ffff888063998258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
#6: ffff888063998258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
#6: ffff888063998258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline]
#6: ffff888063998258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x129a/0x3760 net/core/dev.c:4300
#7: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#7: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#7: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x3e8/0x11b0 net/ipv4/ip_output.c:221
#8: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#8: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
#8: ffffffff8cb2ae80 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257
stack backtrace:
CPU: 1 PID: 8516 Comm: syz.3.916 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
__lock_acquire+0x122f/0x7c50 kernel/locking/lockdep.c:-1
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
__dev_xmit_skb net/core/dev.c:3925 [inline]
__dev_queue_xmit+0x208f/0x3760 net/core/dev.c:4300
dev_queue_xmit include/linux/netdevice.h:3051 [inline]
neigh_hh_output include/net/neighbour.h:528 [inline]
neigh_output include/net/neighbour.h:542 [inline]
ip_finish_output2+0xbe8/0x11b0 net/ipv4/ip_output.c:228
iptunnel_xmit+0x525/0x930 net/ipv4/ip_tunnel_core.c:82
ip_tunnel_xmit+0x1c39/0x2360 net/ipv4/ip_tunnel.c:858
__gre_xmit net/ipv4/ip_gre.c:474 [inline]
gre_tap_xmit+0x50b/0x700 net/ipv4/ip_gre.c:751
__netdev_start_xmit include/linux/netdevice.h:4896 [inline]
netdev_start_xmit include/linux/netdevice.h:4910 [inline]
xmit_one net/core/dev.c:3658 [inline]
dev_hard_start_xmit+0x262/0x870 net/core/dev.c:3674
sch_direct_xmit+0x24e/0x4a0 net/sched/sch_generic.c:342
__dev_xmit_skb net/core/dev.c:3895 [inline]
__dev_queue_xmit+0x18cd/0x3760 net/core/dev.c:4300
__bond_start_xmit include/linux/netdevice.h:-1 [inline]
bond_start_xmit+0x11fb/0x1b90 drivers/net/bonding/bond_main.c:5525
__netdev_start_xmit include/linux/netdevice.h:4896 [inline]
netdev_start_xmit include/linux/netdevice.h:4910 [inline]
xmit_one net/core/dev.c:3658 [inline]
dev_hard_start_xmit+0x262/0x870 net/core/dev.c:3674
__dev_queue_xmit+0x1bf1/0x3760 net/core/dev.c:4334
neigh_output include/net/neighbour.h:544 [inline]
ip6_finish_output2+0xda2/0x1590 net/ipv6/ip6_output.c:138
dst_output include/net/dst.h:453 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ndisc_send_skb+0xbfb/0x1510 net/ipv6/ndisc.c:513
addrconf_rs_timer+0x2b8/0x600 net/ipv6/addrconf.c:3980
call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1504
expire_timers kernel/time/timer.c:1549 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1820
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833
handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x7b/0x290 mm/kasan/generic.c:189
Code: 5c 37 ff 48 c1 eb 03 4e 8d 14 3b 4d 89 d6 4d 29 ce 49 83 fe 10 7f 26 4d 85 f6 0f 84 39 01 00 00 48 f7 d3 4c 01 db 41 80 39 00 <0f> 85 c1 01 00 00 49 ff c1 48 ff c3 75 ee e9 1c 01 00 00 44 89 cb
RSP: 0018:ffffc90005ebf8c0 EFLAGS: 00000246
RAX: ffffffff8a200201 RBX: fffffffffffffffc RCX: ffffffff8a200290
RDX: 0000000000000001 RSI: 0000000000000050 RDI: ffffc90005ebf920
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff52000bd7f2a
R10: fffff52000bd7f2e R11: 1ffff92000bd7f24 R12: 1ffff92000bd7f20
R13: ffff8880280d6e30 R14: 000000000000000a R15: dffffc0000000001
memset+0x1e/0x40 mm/kasan/shadow.c:44
schedule_timeout+0xb0/0x280 kernel/time/timer.c:1928
snd_rawmidi_write+0x391/0xb00 sound/core/rawmidi.c:1605
do_loop_readv_writev fs/read_write.c:-1 [inline]
do_iter_write+0x497/0xaf0 fs/read_write.c:863
vfs_writev fs/read_write.c:934 [inline]
do_writev+0x24e/0x410 fs/read_write.c:977
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7fc7b8eb69
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7fc89cb038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007f7fc7db5fa0 RCX: 00007f7fc7b8eb69
RDX: 0000000000000002 RSI: 0000200000000840 RDI: 0000000000000007
RBP: 00007f7fc7c11df1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f7fc7db5fa0 R15: 00007ffd3ffc37b8
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
----------------
Code disassembly (best guess), 2 bytes skipped:
0: ff 48 c1 decl -0x3f(%rax)
3: eb 03 jmp 0x8
5: 4e 8d 14 3b lea (%rbx,%r15,1),%r10
9: 4d 89 d6 mov %r10,%r14
c: 4d 29 ce sub %r9,%r14
f: 49 83 fe 10 cmp $0x10,%r14
13: 7f 26 jg 0x3b
15: 4d 85 f6 test %r14,%r14
18: 0f 84 39 01 00 00 je 0x157
1e: 48 f7 d3 not %rbx
21: 4c 01 db add %r11,%rbx
24: 41 80 39 00 cmpb $0x0,(%r9)
* 28: 0f 85 c1 01 00 00 jne 0x1ef <-- trapping instruction
2e: 49 ff c1 inc %r9
31: 48 ff c3 inc %rbx
34: 75 ee jne 0x24
36: e9 1c 01 00 00 jmp 0x157
3b: 44 89 cb mov %r9d,%ebx