=============================
WARNING: suspicious RCU usage
5.15.189-syzkaller #0 Not tainted
-----------------------------
net/sched/sch_api.c:304 suspicious rcu_dereference_protected() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
11 locks held by syz.2.83/4707:
#0: ffff88802bb50f28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
#0: ffff88802bb50f28 (&mm->mmap_lock){++++}-{3:3}, at: __mm_populate+0x15e/0x3a0 mm/gup.c:1618
#1: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#2: ffff88801f3384f8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
#2: ffff88801f3384f8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: filemap_map_pages+0xb7d/0x1390 mm/filemap.c:3324
#3: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#4: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#5: ffff88802bb689a0 (k-slock-AF_INET6){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
#5: ffff88802bb689a0 (k-slock-AF_INET6){+.-.}-{2:2}, at: sctp_rcv+0x18c4/0x25b0 net/sctp/input.c:233
#6: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#7: ffffffff8c11c3c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#8: ffffffff8c11c3c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#9: ffff888142f95908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
#9: ffff888142f95908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3911 [inline]
#9: ffff888142f95908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xb8a/0x2ed0 net/core/dev.c:4253
#10: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
stack backtrace:
CPU: 1 PID: 4707 Comm: syz.2.83 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
qdisc_lookup+0xa6/0x650 net/sched/sch_api.c:304
qdisc_tree_reduce_backlog+0x190/0x430 net/sched/sch_api.c:793
sfq_enqueue+0x1164/0x2260 net/sched/sch_sfq.c:471
qdisc_enqueue include/net/sch_generic.h:832 [inline]
tbf_enqueue+0x224/0x6e0 net/sched/sch_tbf.c:243
dev_qdisc_enqueue+0x48/0x210 net/core/dev.c:3852
__dev_xmit_skb net/core/dev.c:3936 [inline]
__dev_queue_xmit+0xd7e/0x2ed0 net/core/dev.c:4253
neigh_hh_output include/net/neighbour.h:493 [inline]
neigh_output include/net/neighbour.h:507 [inline]
ip6_finish_output2+0x1035/0x1500 net/ipv6/ip6_output.c:130
dst_output include/net/dst.h:452 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ip6_xmit+0x1054/0x1670 net/ipv6/ip6_output.c:338
sctp_v6_xmit+0x980/0x1190 net/sctp/ipv6.c:250
sctp_packet_transmit+0x239f/0x2920 net/sctp/output.c:652
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1488 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]
sctp_do_sm+0x17fa/0x5500 net/sctp/sm_sideeffect.c:1170
sctp_endpoint_bh_rcv+0x58e/0x7d0 net/sctp/endpointola.c:402
sctp_rcv+0x1f57/0x25b0 net/sctp/input.c:258
sctp6_rcv+0x35/0x60 net/sctp/ipv6.c:1109
ip6_protocol_deliver_rcu+0x8f0/0x12c0 net/ipv6/ip6_input.c:425
ip6_input_finish+0xa2/0x130 net/ipv6/ip6_input.c:466
NF_HOOK+0x2d6/0x360 include/linux/netfilter.h:302
NF_HOOK+0x2d6/0x360 include/linux/netfilter.h:302
__netif_receive_skb_one_core net/core/dev.c:5525 [inline]
__netif_receive_skb+0xcc/0x290 net/core/dev.c:5639
process_backlog+0x364/0x780 net/core/dev.c:6516
__napi_poll+0xc0/0x430 net/core/dev.c:7075
napi_poll net/core/dev.c:7142 [inline]
net_rx_action+0x4a8/0x9c0 net/core/dev.c:7232
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 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:_compound_head include/linux/page-flags.h:198 [inline]
RIP: 0010:put_page include/linux/mm.h:1233 [inline]
RIP: 0010:filemap_map_pages+0xd7a/0x1390 mm/filemap.c:3351
Code: e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 f7 e8 36 92 1e 00 4d 8b 36 44 89 f6 83 e6 01 31 ff e8 c6 32 da ff <41> f6 c6 01 0f 85 5e 01 00 00 e8 d7 2e da ff 0f 1f 44 00 00 e8 cd
RSP: 0018:ffffc9000432f760 EFLAGS: 00000297
RAX: ffffffff819d953a RBX: ffffea000162b5c0 RCX: ffff88807a270000
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000432f8d0 R08: dffffc0000000000 R09: fffff940002c56b9
R10: fffff940002c56b9 R11: 1ffffd40002c56b8 R12: ffff88805fc943a0
R13: ffffc9000432f9f0 R14: 0000000000000000 R15: 0000000058ad7007
do_fault_around mm/memory.c:4243 [inline]
do_read_fault mm/memory.c:4258 [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+0x2580/0x43c0 mm/memory.c:4883
faultin_page mm/gup.c:976 [inline]
__get_user_pages+0x93e/0x11c0 mm/gup.c:1197
populate_vma_page_range+0x213/0x290 mm/gup.c:1529
__mm_populate+0x26f/0x3a0 mm/gup.c:1638
mm_populate include/linux/mm.h:2635 [inline]
vm_mmap_pgoff+0x203/0x2b0 mm/util.c:556
ksys_mmap_pgoff+0x140/0x780 mm/mmap.c:1631
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: 0033:0x7f254a26cbe9
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:00007f25484d4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f254a493fa0 RCX: 00007f254a26cbe9
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f254a2efe19 R08: ffffffffffffffff R09: 0000000000001000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f254a494038 R14: 00007f254a493fa0 R15: 00007ffc15efa758
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
7: fc ff df
a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1)
e: 74 08 je 0x18
10: 4c 89 f7 mov %r14,%rdi
13: e8 36 92 1e 00 call 0x1e924e
18: 4d 8b 36 mov (%r14),%r14
1b: 44 89 f6 mov %r14d,%esi
1e: 83 e6 01 and $0x1,%esi
21: 31 ff xor %edi,%edi
23: e8 c6 32 da ff call 0xffda32ee
* 28: 41 f6 c6 01 test $0x1,%r14b <-- trapping instruction
2c: 0f 85 5e 01 00 00 jne 0x190
32: e8 d7 2e da ff call 0xffda2f0e
37: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
3c: e8 .byte 0xe8
3d: cd .byte 0xcd