syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P15547
	(detected by 1, t=10505 jiffies, g=108501, q=2073 ncpus=2)
task:syz.2.3451      state:R  running task     stack:21968 pid:15547 ppid:13291  flags:0x0000400c
Call Trace:
 <TASK>
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10486 jiffies! g108501 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=61736
rcu: rcu_preempt kthread starved for 10487 jiffies! g108501 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:26864 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 15547 Comm: syz.2.3451 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:trace_call_bpf+0x0/0x6b0 kernel/trace/bpf_trace.c:103
Code: 66 2e 0f 1f 84 00 00 00 00 00 41 56 53 48 89 f3 49 89 fe e8 52 56 f6 ff 4c 89 f7 48 89 de 5b 41 5e e9 44 62 00 00 0f 1f 40 00 <55> 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec c0 00
RSP: 0018:ffffc90000007be0 EFLAGS: 00000046
RAX: 1ffffd1ffff9aa00 RBX: ffffffff8cb804a0 RCX: ffff88802f4a5940
RDX: 0000000000000100 RSI: ffffe8ffffcd5000 RDI: ffffffff8cb80420
RBP: 0000000000000014 R08: 0000000000000001 R09: ffff8880b8e35558
R10: dffffc0000000000 R11: ffffed10171c6b02 R12: ffffe8ffffcd5000
R13: ffffffff8cb80420 R14: ffff8880b8e35558 R15: dffffc0000000000
FS:  00007f8c0cab06c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c0bbea540 CR3: 0000000050fac000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10027
 perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:variable_ffs arch/x86/include/asm/bitops.h:319 [inline]
RIP: 0010:handle_softirqs+0x1c8/0x930 kernel/softirq.c:584
Code: 89 7c 24 44 0f b7 db 48 c7 c7 80 0f 8b 8a e8 2f 90 de 08 65 66 c7 05 15 25 b4 7e 00 00 e8 50 74 39 00 fb 49 c7 c6 c0 a0 80 8c <89> 5c 24 4c b8 ff ff ff ff 0f bc 44 24 4c 41 89 c5 41 ff c5 0f 84
RSP: 0018:ffffc90000007e00 EFLAGS: 00000286
RAX: 11fb42e869582c00 RBX: 0000000000000200 RCX: 11fb42e869582c00
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf1ba0
RBP: ffffc90000007f30 R08: ffff8880b8e3580b R09: 1ffff110171c6b01
R10: dffffc0000000000 R11: ffffed10171c6b02 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff8c80a0c0 R15: 000000000000000a
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:rcu_read_unlock_special+0x0/0x510 kernel/rcu/tree_plugin.h:630
Code: b6 46 66 00 eb b0 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 94 49 89 fd 4c 89 f7 e8 9c 46 66 00 4c 89 ef eb 84 0f 1f 80 00 00 00 00 <55> 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec c0 00
RSP: 0018:ffffc900033375d8 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff88802f4a5d7c RCX: 0000000000080000
RDX: ffffc9001c0bf000 RSI: 000000000002fe3b RDI: ffff88802f4a5940
RBP: ffffc90003337788 R08: ffffffff8e1ffbef R09: 1ffffffff1c3ff7d
R10: dffffc0000000000 R11: fffffbfff1c3ff7e R12: 1ffff11005e94baf
R13: 0000000000000000 R14: ffff88802f4a5d80 R15: dffffc0000000000
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock+0x85/0xa0 include/linux/rcupdate.h:823
 rawv6_send_hdrinc+0xf03/0x16c0 net/ipv6/raw.c:663
 rawv6_sendmsg+0x11b3/0x1700 net/ipv6/raw.c:912
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5be/0x970 net/socket.c:2518
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2572
 __sys_sendmsg net/socket.c:2601 [inline]
 __do_sys_sendmsg net/socket.c:2610 [inline]
 __se_sys_sendmsg+0x1bb/0x2a0 net/socket.c:2608
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8c0bb9ce59
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:00007f8c0cab0028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8c0be15fa0 RCX: 00007f8c0bb9ce59
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000006
RBP: 00007f8c0bc32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8c0be16038 R14: 00007f8c0be15fa0 R15: 00007ffff63cced8
 </TASK>