syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10511 ticks this GP) idle=029c/0/0x1 softirq=16566/16568 fqs=0
	(t=10500 jiffies g=19985 q=34 ncpus=2)
rcu: rcu_preempt kthread starved for 10500 jiffies! g19985 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 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: 5874 Comm: syz.4.354 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:-1 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:lock_release+0x15d/0x910 kernel/locking/lockdep.c:5678
Code: 83 3b 00 0f 85 4e 04 00 00 4c 89 74 24 08 48 c7 84 24 a0 00 00 00 00 00 00 00 9c 8f 84 24 a0 00 00 00 48 8b 84 24 a0 00 00 00 <48> 89 44 24 50 fa 48 c7 c7 c0 0c 6c 8a e8 81 39 ac 08 65 ff 05 1a
RSP: 0018:ffffc900049b7dc0 EFLAGS: 00000246
RAX: 0000000000000246 RBX: ffff888024c4465c RCX: a15b3fbc34c17c00
RDX: 0000000000000000 RSI: ffffffff8abf1340 RDI: ffffffff8abf1300
RBP: ffffc900049b7ec8 R08: dffffc0000000000 R09: fffffbfff1bfd0b6
R10: fffffbfff1bfd0b6 R11: 1ffffffff1bfd0b5 R12: ffff8880236d4d68
R13: dffffc0000000000 R14: ffff888024c43b80 R15: 1ffff92000936fc4
FS:  00007fbaf23796c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c4285df CR3: 00000000186e0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rcu_lock_release include/linux/rcupdate.h:355 [inline]
 rcu_read_unlock include/linux/rcupdate.h:824 [inline]
 __task_pid_nr_ns+0x387/0x460 kernel/pid.c:501
 task_tgid_vnr include/linux/sched.h:1628 [inline]
 __ia32_sys_getpid+0x19/0x20 kernel/sys.c:953
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fbaf15858e7
Code: 0b e9 68 fe ff ff 48 83 c4 18 48 8d 3d b2 6f d6 00 5b 5d 41 5c 41 5d 41 5e 41 5f e9 13 f8 fb ff 0f 1f 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00
RSP: 002b:00007fbaf2378b08 EFLAGS: 00000202 ORIG_RAX: 0000000000000027
RAX: ffffffffffffffda RBX: 00007fbaf2378c70 RCX: 00007fbaf15858e7
RDX: 00007fbaf2378b40 RSI: 00007fbaf2378c70 RDI: 0000000000000021
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007fbaf17b616c
R13: 0000000000000000 R14: 00007ffde8892070 R15: 00007ffde8892158
 </TASK>
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:736
Code: 48 89 df e8 47 d4 b8 f7 e9 4c ff ff ff e8 bd 15 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 17 24 4d 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffc90000177de8 EFLAGS: 000002c6
RAX: 6047ad8c07227f00 RBX: ffffffff8a197f77 RCX: 6047ad8c07227f00
RDX: 0000000000000001 RSI: ffffffff8a6bffe0 RDI: ffffffff8abf1360
RBP: ffffc90000177f20 R08: dffffc0000000000 R09: ffffed10171e6af6
R10: ffffed10171e6af6 R11: 1ffff110171e6af5 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff88813feb9dc0 R15: 1ffffffff1bfd0f6
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9cd14502e5 CR3: 00000000186e0000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1fc/0x570 kernel/sched/idle.c:303
 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401
 start_secondary+0xe4/0xf0 arch/x86/kernel/smpboot.c:281
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>