============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.5.696/7274 is trying to acquire lock:
ffff888078dc1c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffff888078dc1c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
ffff888078dc1c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x14b5/0x2f80 net/core/dev.c:4299
but task is already holding lock:
ffff88802553f898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffff88802553f898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
ffff88802553f898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x162/0x4b0 net/sched/sch_generic.c:343
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(_xmit_ETHER#2);
lock(_xmit_ETHER#2);
*** DEADLOCK ***
May be due to missing lock nesting notation
10 locks held by syz.5.696/7274:
#0: ffff88807b107828 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
#0: ffff88807b107828 (&mm->mmap_lock){++++}-{3:3}, at: __mm_populate+0x164/0x3b0 mm/gup.c:1618
#1: ffffc90000dd0be0 ((&in_dev->mr_ifc_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#1: ffffc90000dd0be0 ((&in_dev->mr_ifc_timer)){+.-.}-{0:0}, at: call_timer_fn+0xca/0x540 kernel/time/timer.c:1638
#2: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#3: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#4: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#5: ffff88807b52b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline]
#5: ffff88807b52b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
#5: ffff88807b52b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3884 [inline]
#5: ffff88807b52b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1120/0x2f80 net/core/dev.c:4266
#6: ffff88802553f898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
#6: ffff88802553f898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
#6: ffff88802553f898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x162/0x4b0 net/sched/sch_generic.c:343
#7: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#8: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#9: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
stack backtrace:
CPU: 1 PID: 7274 Comm: syz.5.696 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
__lock_acquire+0x1236/0x7d10 kernel/locking/lockdep.c:-1
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:364 [inline]
__netif_tx_lock include/linux/netdevice.h:4446 [inline]
__dev_queue_xmit+0x14b5/0x2f80 net/core/dev.c:4299
neigh_hh_output include/net/neighbour.h:493 [inline]
neigh_output include/net/neighbour.h:507 [inline]
ip_finish_output2+0xc87/0x10a0 net/ipv4/ip_output.c:228
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip_output+0x2c0/0x3e0 net/ipv4/ip_output.c:434
iptunnel_xmit+0x4d6/0x8e0 net/ipv4/ip_tunnel_core.c:82
ip_tunnel_xmit+0x1905/0x2280 net/ipv4/ip_tunnel.c:824
__gre_xmit net/ipv4/ip_gre.c:474 [inline]
erspan_xmit+0x9d5/0x15a0 net/ipv4/ip_gre.c:723
__netdev_start_xmit include/linux/netdevice.h:5036 [inline]
netdev_start_xmit include/linux/netdevice.h:5050 [inline]
xmit_one net/core/dev.c:3662 [inline]
dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3678
sch_direct_xmit+0x25a/0x4b0 net/sched/sch_generic.c:345
__dev_xmit_skb net/core/dev.c:3897 [inline]
__dev_queue_xmit+0x179f/0x2f80 net/core/dev.c:4266
neigh_output include/net/neighbour.h:509 [inline]
ip_finish_output2+0xcbf/0x10a0 net/ipv4/ip_output.c:228
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip_output+0x2c0/0x3e0 net/ipv4/ip_output.c:434
igmpv3_send_cr net/ipv4/igmp.c:723 [inline]
igmp_ifc_timer_expire+0xb76/0xda0 net/ipv4/igmp.c:813
call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
expire_timers kernel/time/timer.c:1699 [inline]
__run_timers+0x53e/0x800 kernel/time/timer.c:1970
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
handle_softirqs+0x339/0x830 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:preempt_count_add+0x56/0x190 kernel/sched/core.c:5512
Code: 14 00 75 07 65 8b 05 f1 fe af 7e 65 01 3d ea fe af 7e 48 c7 c0 80 bf 2d 96 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 e6 00 00 00 <83> 3d 83 4e db 14 00 75 11 65 8b 05 c2 fe af 7e 0f b6 c0 3d f5 00
RSP: 0018:ffffc9000330eb88 EFLAGS: 00000297
RAX: 0000000000000004 RBX: ffffc9000330ec68 RCX: ffffffff962dbf03
RDX: dffffc0000000000 RSI: ffffffff89e000ca RDI: 0000000000000001
RBP: ffffc9000330ecb0 R08: ffffc9000330ed30 R09: 000000000000000e
R10: dffffc0000000000 R11: fffff52000661d99 R12: ffffffff89e000ca
R13: ffffc9000330ff58 R14: dffffc0000000000 R15: dffffc0000000000
unwind_next_frame+0xac/0x1d90 arch/x86/kernel/unwind_orc.c:433
arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
save_stack+0x121/0x230 mm/page_owner.c:119
__set_page_owner+0x41/0x2d0 mm/page_owner.c:181
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
__alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
alloc_pages_vma+0x393/0x7c0 mm/mempolicy.c:2146
shmem_alloc_page mm/shmem.c:1586 [inline]
shmem_alloc_and_acct_page+0x47f/0xbe0 mm/shmem.c:1611
shmem_getpage_gfp+0x14f4/0x2d40 mm/shmem.c:1906
shmem_fault+0x1ac/0x540 mm/shmem.c:2118
__do_fault+0x141/0x330 mm/memory.c:3928
do_read_fault mm/memory.c:4264 [inline]
do_fault mm/memory.c:4392 [inline]
handle_pte_fault mm/memory.c:4650 [inline]
__handle_mm_fault mm/memory.c:4785 [inline]
handle_mm_fault+0x2985/0x4410 mm/memory.c:4883
faultin_page mm/gup.c:976 [inline]
__get_user_pages+0x94b/0x11e0 mm/gup.c:1197
populate_vma_page_range+0x213/0x290 mm/gup.c:1529
__mm_populate+0x275/0x3b0 mm/gup.c:1638
mm_populate include/linux/mm.h:2646 [inline]
vm_mmap_pgoff+0x212/0x2d0 mm/util.c:556
ksys_mmap_pgoff+0x140/0x790 mm/mmap.c:1635
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb884c02dd9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb882e5c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fb884e7bfa0 RCX: 00007fb884c02dd9
RDX: b635773f07ebbeea RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007fb884c98d69 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb884e7c038 R14: 00007fb884e7bfa0 R15: 00007ffc511e8888
----------------
Code disassembly (best guess):
0: 14 00 adc $0x0,%al
2: 75 07 jne 0xb
4: 65 8b 05 f1 fe af 7e mov %gs:0x7eaffef1(%rip),%eax # 0x7eaffefc
b: 65 01 3d ea fe af 7e add %edi,%gs:0x7eaffeea(%rip) # 0x7eaffefc
12: 48 c7 c0 80 bf 2d 96 mov $0xffffffff962dbf80,%rax
19: 48 c1 e8 03 shr $0x3,%rax
1d: 42 0f b6 04 38 movzbl (%rax,%r15,1),%eax
22: 84 c0 test %al,%al
24: 0f 85 e6 00 00 00 jne 0x110
* 2a: 83 3d 83 4e db 14 00 cmpl $0x0,0x14db4e83(%rip) # 0x14db4eb4 <-- trapping instruction
31: 75 11 jne 0x44
33: 65 8b 05 c2 fe af 7e mov %gs:0x7eaffec2(%rip),%eax # 0x7eaffefc
3a: 0f b6 c0 movzbl %al,%eax
3d: 3d .byte 0x3d
3e: f5 cmc