=============================
WARNING: suspicious RCU usage
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
5 locks held by syz-executor/10581:
#0: ffff888020dcf518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf9/0x7d0 block/bdev.c:915
#1: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
#2: ffffc90000dd0c00 ((&q->perturb_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#2: ffffc90000dd0c00 ((&q->perturb_timer)){+.-.}-{0:0}, at: call_timer_fn+0xca/0x540 kernel/time/timer.c:1638
#3: ffff8880771d5108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
#3: ffff8880771d5108 (&sch->q.lock){+.-.}-{2:2}, at: sfq_perturbation+0x14d/0x20d0 net/sched/sch_sfq.c:610
#4: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
stack backtrace:
CPU: 1 PID: 10581 Comm: syz-executor 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
qdisc_lookup+0xa6/0x650 net/sched/sch_api.c:304
qdisc_tree_reduce_backlog+0x190/0x430 net/sched/sch_api.c:783
sfq_rehash net/sched/sch_sfq.c:598 [inline]
sfq_perturbation+0x1f5e/0x20d0 net/sched/sch_sfq.c:613
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
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:xas_find+0x819/0xab0 lib/xarray.c:1262
Code: 48 8b 44 24 30 42 80 3c 28 00 4c 89 eb 74 08 4c 89 f7 e8 3a e7 b4 fd 49 8b 3e 48 89 ee e8 4f ef ff ff 48 89 c5 48 8b 44 24 20 <80> 3c 18 00 4c 8b 2c 24 74 08 4c 89 ff e8 95 e7 b4 fd 49 89 2f 4c
RSP: 0018:ffffc900032bf7e8 EFLAGS: 00000293
RAX: 1ffff92000657f1f RBX: dffffc0000000000 RCX: ffff8880291a8000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffff888049232680 R08: ffff8880291a8000 R09: 0000000000000002
R10: 0000000000000003 R11: 0000000000000000 R12: 1ffff92000657f1e
R13: dffffc0000000000 R14: ffffc900032bf8e0 R15: ffffc900032bf8f8
find_get_entry mm/filemap.c:1978 [inline]
find_lock_entries+0x19e/0xd70 mm/filemap.c:2092
truncate_inode_pages_range+0x1cf/0xfe0 mm/truncate.c:320
kill_bdev block/bdev.c:77 [inline]
blkdev_flush_mapping+0x188/0x360 block/bdev.c:659
blkdev_put_whole block/bdev.c:690 [inline]
blkdev_put+0x4d1/0x7d0 block/bdev.c:957
kill_f2fs_super+0x309/0x3c0 fs/f2fs/super.c:4568
deactivate_locked_super+0x93/0xf0 fs/super.c:335
cleanup_mnt+0x42d/0x4e0 fs/namespace.c:1148
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f19726ca017
Code: a2 c7 05 dc 06 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffdbf49d8c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f197275e120 RCX: 00007f19726ca017
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffdbf49d980
RBP: 00007ffdbf49d980 R08: 00007ffdbf49e980 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdbf49ea10
R13: 00007f197275e120 R14: 0000000000084b48 R15: 00007ffdbf49ea50
----------------
Code disassembly (best guess):
0: 48 8b 44 24 30 mov 0x30(%rsp),%rax
5: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1)
a: 4c 89 eb mov %r13,%rbx
d: 74 08 je 0x17
f: 4c 89 f7 mov %r14,%rdi
12: e8 3a e7 b4 fd call 0xfdb4e751
17: 49 8b 3e mov (%r14),%rdi
1a: 48 89 ee mov %rbp,%rsi
1d: e8 4f ef ff ff call 0xffffef71
22: 48 89 c5 mov %rax,%rbp
25: 48 8b 44 24 20 mov 0x20(%rsp),%rax
* 2a: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1) <-- trapping instruction
2e: 4c 8b 2c 24 mov (%rsp),%r13
32: 74 08 je 0x3c
34: 4c 89 ff mov %r15,%rdi
37: e8 95 e7 b4 fd call 0xfdb4e7d1
3c: 49 89 2f mov %rbp,(%r15)
3f: 4c rex.WR