------------[ cut here ]------------
WARNING: CPU: 1 PID: 1 at kernel/rcu/tree_stall.h:826 rcu_check_gp_start_stall.part.0+0x325/0x4b0 kernel/rcu/tree_stall.h:818
Modules linked in:
CPU: 1 PID: 1 Comm: systemd Not tainted 5.13.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
RIP: 0010:rcu_check_gp_start_stall.part.0+0x325/0x4b0 kernel/rcu/tree_stall.h:826
Code: 0f 88 fa 00 00 00 be 04 00 00 00 48 c7 c7 a0 44 77 90 e8 5e d9 58 00 b8 01 00 00 00 87 05 b3 4b 16 0f 85 c0 0f 85 c9 00 00 00 <0f> 0b 48 81 fd 80 1e f8 8b 48 c7 c3 ac 89 c9 8d 74 58 48 b8 00 00
RSP: 0018:ffffc900004f8e30 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000100003b42 RCX: ffffffff8160f8e2
RDX: fffffbfff20ee894 RSI: 0000000000000004 RDI: ffffffff907744a0
RBP: ffffffff8bf81e80 R08: 0000000000000001 R09: 0000000000000003
R10: fffffbfff20ee894 R11: 1ffff11005966c2e R12: 1ffffffff1781e30
R13: 0000000000000246 R14: ffff88802cb36092 R15: 000000000000000a
FS:  00007ff14603e500(0000) GS:ffff88802cb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c004bbdd38 CR3: 0000000022052000 CR4: 0000000000150ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_check_gp_start_stall kernel/rcu/tree_stall.h:789 [inline]
 rcu_core+0x4df/0x13b0 kernel/rcu/tree.c:2788
 __do_softirq+0x29b/0x9f6 kernel/softirq.c:559
 invoke_softirq kernel/softirq.c:433 [inline]
 __irq_exit_rcu+0x136/0x200 kernel/softirq.c:637
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:647
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:199
Code: 0f 1f 44 00 00 55 48 8b 74 24 08 48 89 fd 48 83 c7 18 e8 3e b9 41 f8 48 89 ef e8 d6 31 42 f8 e8 31 23 62 f8 fb bf 01 00 00 00 <e8> 36 2a 36 f8 65 8b 05 0f 33 e9 76 85 c0 74 02 5d c3 e8 cb 88 e7
RSP: 0018:ffffc9000032fba8 EFLAGS: 00000202
RAX: 00000000003afc3b RBX: 0000000000000002 RCX: 1ffffffff20449d2
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffffffff8bfb9fa0 R08: 0000000000000001 R09: ffffffff902248a7
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff8bfb79f0 R14: dffffc0000000000 R15: ffffffff8bfb7600
 spin_unlock_irq include/linux/spinlock.h:404 [inline]
 proc_cgroup_show+0x51a/0x850 kernel/cgroup/cgroup.c:5850
 proc_single_show+0x116/0x1e0 fs/proc/base.c:774
 seq_read_iter+0x4d3/0x1220 fs/seq_file.c:227
 seq_read+0x3dd/0x5b0 fs/seq_file.c:159
 vfs_read+0x1b5/0x570 fs/read_write.c:494
 ksys_read+0x12d/0x250 fs/read_write.c:634
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7ff144607910
Code: b6 fe ff ff 48 8d 3d 0f be 08 00 48 83 ec 08 e8 06 db 01 00 66 0f 1f 44 00 00 83 3d f9 2d 2c 00 00 75 10 b8 00 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 de 9b 01 00 48 89 04 24
RSP: 002b:00007ffc7a79ad48 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000055a055a92e50 RCX: 00007ff144607910
RDX: 0000000000000400 RSI: 000055a055a12320 RDI: 0000000000000013
RBP: 0000000000000d68 R08: 00007ff1448c61d8 R09: 0000000000000410
R10: 0000000000000030 R11: 0000000000000246 R12: 00007ff1448c2440
R13: 00007ff1448c1900 R14: 00000000000007ff R15: 000055a055a92e50