=============================
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
9 locks held by syz.1.50/4441:
#0: ffff888022f2f828 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
#0: ffff888022f2f828 (&mm->mmap_lock){++++}-{3:3}, at: __mm_populate+0x15e/0x3a0 mm/gup.c:1618
#1: ffff888076910f18 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
#1: ffff888076910f18 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: finish_fault+0x4af/0x8d0 mm/memory.c:4138
#2: ffffffff8c11c460 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
#3: ffffc90000007be0 ((&d->timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#3: ffffc90000007be0 ((&d->timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x530 kernel/time/timer.c:1441
#4: ffffffff8c11c460 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#5: ffffffff8c11c4c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#6: ffff8880758ae108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
#6: ffff8880758ae108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3911 [inline]
#6: ffff8880758ae108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xb8a/0x2ed0 net/core/dev.c:4253
#7: ffff8880758ae148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: tipc_l2_send_msg+0x30a/0x3c0 net/tipc/bearer.c:518
#8: ffffffff8c11c460 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
stack backtrace:
CPU: 0 PID: 4441 Comm: syz.1.50 Not tainted 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
cake_drop net/sched/sch_cake.c:1611 [inline]
cake_enqueue+0x3889/0x7bb0 net/sched/sch_cake.c:1948
qdisc_enqueue include/net/sch_generic.h:832 [inline]
netem_dequeue+0xd39/0x1400 net/sched/sch_netem.c:737
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
__dev_xmit_skb net/core/dev.c:3942 [inline]
__dev_queue_xmit+0xeb9/0x2ed0 net/core/dev.c:4253
tipc_l2_send_msg+0x30a/0x3c0 net/tipc/bearer.c:518
tipc_bearer_xmit_skb+0x292/0x3c0 net/tipc/bearer.c:577
tipc_disc_timeout+0x568/0x6b0 net/tipc/discover.c:338
call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
expire_timers kernel/time/timer.c:1496 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1767
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
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:instrument_atomic_read include/linux/instrumented.h:71 [inline]
RIP: 0010:atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
RIP: 0010:lock_page_memcg+0x20c/0x410 mm/memcontrol.c:2062
Code: ff 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 f6 44 24 41 02 0f 85 f9 00 00 00 f7 c3 00 02 00 00 74 01 fb 4d 8d af 80 10 00 00 <4c> 89 ef be 04 00 00 00 e8 67 95 fb ff 4c 89 e8 48 c1 e8 03 48 b9
RSP: 0018:ffffc90002f8f700 EFLAGS: 00000206
RAX: e7da789f02880f00 RBX: 0000000000000286 RCX: e7da789f02880f00
RDX: dffffc0000000000 RSI: ffffffff8a0b1620 RDI: ffffffff8a59a240
RBP: ffffc90002f8f7d0 R08: dffffc0000000000 R09: fffffbfff1ff7619
R10: fffffbfff1ff7619 R11: 1ffffffff1ff7618 R12: ffff88805fb08670
R13: ffff88805fb09080 R14: ffffea0001c07778 R15: ffff88805fb08000
page_add_file_rmap+0x185/0x940 mm/rmap.c:1219
do_set_pte+0x3c9/0x530 mm/memory.c:4069
finish_fault+0x52e/0x8d0 mm/memory.c:4143
do_read_fault mm/memory.c:4268 [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+0x296f/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:2646 [inline]
vm_mmap_pgoff+0x203/0x2b0 mm/util.c:556
ksys_mmap_pgoff+0x140/0x780 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: 0033:0x7f62739d0be9
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:00007f6271c38038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f6273c07fa0 RCX: 00007f62739d0be9
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f6273a53e19 R08: ffffffffffffffff R09: 00000000ffffe000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6273c08038 R14: 00007f6273c07fa0 R15: 00007ffd729863f8
----------------
Code disassembly (best guess):
0: ff 48 c7 decl -0x39(%rax)
3: 44 24 40 rex.R and $0x40,%al
6: 00 00 add %al,(%rax)
8: 00 00 add %al,(%rax)
a: 9c pushf
b: 8f 44 24 40 pop 0x40(%rsp)
f: f6 44 24 41 02 testb $0x2,0x41(%rsp)
14: 0f 85 f9 00 00 00 jne 0x113
1a: f7 c3 00 02 00 00 test $0x200,%ebx
20: 74 01 je 0x23
22: fb sti
23: 4d 8d af 80 10 00 00 lea 0x1080(%r15),%r13
* 2a: 4c 89 ef mov %r13,%rdi <-- trapping instruction
2d: be 04 00 00 00 mov $0x4,%esi
32: e8 67 95 fb ff call 0xfffb959e
37: 4c 89 e8 mov %r13,%rax
3a: 48 c1 e8 03 shr $0x3,%rax
3e: 48 rex.W
3f: b9 .byte 0xb9