=============================
WARNING: suspicious RCU usage
5.15.185-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
7 locks held by syz.1.209/5340:
 #0: ffff88807ac03928 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
 #0: ffff88807ac03928 (&mm->mmap_lock){++++}-{3:3}, at: __mm_populate+0x15e/0x3a0 mm/gup.c:1618
 #1: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
 #2: ffff888023ee3258 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #2: ffff888023ee3258 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: filemap_map_pages+0xb7d/0x1390 mm/filemap.c:3324
 #3: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
 #4: ffff88807d02c148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: net_tx_action+0x6bc/0x870 net/core/dev.c:5128
 #5: ffff88807d02c108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #5: ffff88807d02c108 (&sch->q.lock){+.-.}-{2:2}, at: sch_direct_xmit+0x305/0x4a0 net/sched/sch_generic.c:354
 #6: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311

stack backtrace:
CPU: 1 PID: 5340 Comm: syz.1.209 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 qdisc_lookup+0xa6/0x650 net/sched/sch_api.c:304
 qdisc_tree_reduce_backlog+0x213/0x4e0 net/sched/sch_api.c:800
 codel_qdisc_dequeue+0x1523/0x2100 net/sched/sch_codel.c:102
 qdisc_peek_dequeued+0x6e/0x1f0 include/net/sch_generic.h:1115
 tbf_dequeue+0x7d/0xce0 net/sched/sch_tbf.c:265
 dequeue_skb net/sched/sch_generic.c:292 [inline]
 qdisc_restart net/sched/sch_generic.c:397 [inline]
 __qdisc_run+0x237/0x1480 net/sched/sch_generic.c:415
 qdisc_run+0x103/0x2f0 include/net/pkt_sched.h:132
 net_tx_action+0x6bc/0x870 net/core/dev.c:5128
 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
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:91 [inline]
RIP: 0010:lock_is_held_type+0x45/0x190 kernel/locking/lockdep.c:5659
Code: 08 bd ff ff ff ff 83 3d 3c 70 c7 03 00 0f 84 03 01 00 00 65 8b 05 ab 09 61 76 85 c0 0f 85 f4 00 00 00 65 48 8b 1d 5b 00 61 76 <83> bb ec 0a 00 00 00 0f 85 df 00 00 00 41 89 f7 49 89 fe 48 c7 04
RSP: 0018:ffffc9000379f678 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888027ef3b80 RCX: 3c5da9af02aa8100
RDX: 0000000000000002 RSI: 00000000ffffffff RDI: ffffffff8c11bfa0
RBP: 00000000ffffffff R08: dffffc0000000000 R09: fffff94000286287
R10: fffff94000286287 R11: 1ffffd4000286286 R12: ffff888026f9a8c0
R13: 1ffff920006f3f04 R14: ffff888070c29080 R15: ffffc9000379f820
 xa_entry include/linux/xarray.h:1182 [inline]
 xas_reload+0x19c/0x470 include/linux/xarray.h:1558
 next_uptodate_page+0x2a5/0x8b0 mm/filemap.c:3259
 next_map_page mm/filemap.c:3296 [inline]
 filemap_map_pages+0xebd/0x1390 mm/filemap.c:3352
 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:2632 [inline]
 vm_mmap_pgoff+0x203/0x2b0 mm/util.c:556
 ksys_mmap_pgoff+0x140/0x780 mm/mmap.c:1623
 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: 0033:0x7f6a139ae929
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:00007f6a11816038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f6a13bd5fa0 RCX: 00007f6a139ae929
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f6a13a30b39 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6a13bd5fa0 R15: 00007ffe69a56b68
 </TASK>
----------------
Code disassembly (best guess):
   0:	08 bd ff ff ff ff    	or     %bh,-0x1(%rbp)
   6:	83 3d 3c 70 c7 03 00 	cmpl   $0x0,0x3c7703c(%rip)        # 0x3c77049
   d:	0f 84 03 01 00 00    	je     0x116
  13:	65 8b 05 ab 09 61 76 	mov    %gs:0x766109ab(%rip),%eax        # 0x766109c5
  1a:	85 c0                	test   %eax,%eax
  1c:	0f 85 f4 00 00 00    	jne    0x116
  22:	65 48 8b 1d 5b 00 61 	mov    %gs:0x7661005b(%rip),%rbx        # 0x76610085
  29:	76
* 2a:	83 bb ec 0a 00 00 00 	cmpl   $0x0,0xaec(%rbx) <-- trapping instruction
  31:	0f 85 df 00 00 00    	jne    0x116
  37:	41 89 f7             	mov    %esi,%r15d
  3a:	49 89 fe             	mov    %rdi,%r14
  3d:	48                   	rex.W
  3e:	c7                   	.byte 0xc7
  3f:	04                   	.byte 0x4