rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10484 ticks this GP) idle=6a6c/1/0x4000000000000000 softirq=58497/58762 fqs=5203
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:  1172236        753            0
rcu: 	cputime:    30295      22191           44   ==> 52490(ms)
rcu: 	(t=10502 jiffies g=51089 q=6121 ncpus=2)
CPU: 0 UID: 0 PID: 15750 Comm: syz.9.2931 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80
Code: f7 e8 1d c1 f0 f5 f7 c3 00 02 00 00 74 05 e8 d0 1a 1c f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> e4 7d e2 f5 65 8b 05 0d f0 6a 07 85 c0 74 18 5b 41 5e c3 cc cc
RSP: 0018:ffffc90000007c68 EFLAGS: 00000206
RAX: 0000000000000006 RBX: 0000000000000286 RCX: 0000000000000102
RDX: 0000000000000002 RSI: ffffffff8def914b RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff9011b4b7 R09: 1ffffffff2023696
R10: dffffc0000000000 R11: fffffbfff2023697 R12: ffff888113244900
R13: ffff888113244800 R14: ffffffff9a5392e8 R15: 0000000000000001
FS:  00007f7ba9ff66c0(0000) GS:ffff88818de5a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f14196f680 CR3: 00000001ae602000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0100000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 debug_check_no_obj_freed+0x52e/0x550
 __rcu_free_sheaf_prepare+0xdb/0x290
 rcu_free_sheaf+0x31/0x200
 rcu_core+0x7cd/0x1070
 handle_softirqs+0x22a/0x870
 __irq_exit_rcu+0x5f/0x150
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:finish_task_switch+0x245/0x920
Code: 00 00 48 85 db 0f 85 e8 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 49 83 c4 48 4c 89 e7 e8 d5 65 1c 0a e8 30 81 38 00 fb 4c 8b 65 c0 <49> 8d bc 24 80 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90004ed75f8 EFLAGS: 00000206
RAX: 000000000003663f RBX: 0000000000000000 RCX: 0000000080000001
RDX: 0000000000000006 RSI: ffffffff8def914b RDI: ffffffff8c27ca00
RBP: ffffc90004ed7650 R08: ffffffff9011b4b7 R09: 1ffffffff2023696
R10: dffffc0000000000 R11: fffffbfff2023697 R12: ffff888174f20000
R13: dffffc0000000000 R14: ffff888109ed3a80 R15: ffff88812103b998
 __schedule+0x15e5/0x52d0
 preempt_schedule_irq+0x4d/0xa0
 irqentry_exit+0x599/0x620
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:__mutex_unlock_slowpath+0xc4/0x7d0
Code: 88 00 00 00 48 89 f8 48 c1 e8 03 48 89 44 24 38 42 80 3c 28 00 74 0b 48 89 f3 e8 c7 c5 7f f6 48 89 de 4c 89 b4 24 88 00 00 00 <43> c6 44 2c 0c 00 49 8d 7f 68 e8 1d 82 f1 f5 4c 89 ff be 08 00 00
RSP: 0018:ffffc90004ed7980 EFLAGS: 00000246
RAX: 1ffff920009daf41 RBX: ffff8881772c4980 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffffffff8195a5d6 RDI: ffffc90004ed7a08
RBP: ffffc90004ed7a98 R08: ffffffff9011b4b7 R09: 1ffffffff2023696
R10: dffffc0000000000 R11: fffffbfff2023697 R12: 1ffff920009daf38
R13: dffffc0000000000 R14: ffffc90004ed7a00 R15: ffff8881772c4b38
 sched_mm_cid_exit+0x3a6/0x500
 do_exit+0x3a0/0x23c0
 do_group_exit+0x21b/0x2d0
 get_signal+0x1284/0x1330
 arch_do_signal_or_restart+0xbc/0x830
 exit_to_user_mode_loop+0x86/0x480
 do_syscall_64+0x32d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7babd9c819
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:00007f7ba9ff6028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: 0000000000000006 RBX: 00007f7bac015fa0 RCX: 00007f7babd9c819
RDX: bfffffffffffffff RSI: 0000000000000000 RDI: 0000200000000180
RBP: 00007f7babe32c91 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7bac016038 R14: 00007f7bac015fa0 R15: 00007ffe878b5c98
 </TASK>
sched: DL replenish lagged too much
