rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=b51c/1/0x4000000000000000 softirq=79032/79032 fqs=1
rcu: 	(detected by 0, t=10506 jiffies, g=76037, q=513 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 14125 Comm: syz.7.1274 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:percpu_counter_tree_items_size+0x0/0x80
Code: 07 80 c1 03 38 c1 0f 8c 15 fc ff ff 4c 89 ef e8 86 8e 47 fd e9 08 fc ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 53 e8 d6 4e de fc 8b 1d 70 9b 74 15 31 ff 89 de e8 07
RSP: 0018:ffffc900063d7c08 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff888113e4d790 RCX: dffffc0000000000
RDX: ffffc90024411000 RSI: 0000000000000002 RDI: ffff888113e4d890
RBP: ffff888110c8b348 R08: 1ffff110227c99b1 R09: 0000000000000000
R10: ffff888113e4ced4 R11: fffff52000c7af78 R12: dffffc0000000000
R13: 1ffffffff1c36bd3 R14: 0000000080000000 R15: 0000000000000002
FS:  00007fbc414626c0(0000) GS:ffff8882a9463000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f815ab77028 CR3: 000000010d326000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 mm_get_cid+0xd6/0x160
 sched_mm_cid_fork+0x3f6/0xdf0
 bprm_execve+0xda1/0x1460
 do_execveat_common+0x50d/0x690
 __x64_sys_execveat+0xc7/0xf0
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbc4059c799
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:00007fbc41462028 EFLAGS: 00000246 ORIG_RAX: 0000000000000142
RAX: ffffffffffffffda RBX: 00007fbc40815fa0 RCX: 00007fbc4059c799
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000005
RBP: 00007fbc40632c99 R08: 0000000000001000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbc40816038 R14: 00007fbc40815fa0 R15: 00007ffebd01ce78
 </TASK>
rcu: rcu_preempt kthread starved for 10500 jiffies! g76037 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:27744 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x15dd/0x5300
 schedule+0x164/0x360
 schedule_timeout+0x158/0x2c0
 rcu_gp_fqs_loop+0x312/0x11d0
 rcu_gp_kthread+0x9e/0x2b0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 14151 Comm: udevadm Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:smp_call_function_many_cond+0xce5/0x12c0
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 c4 e6 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 6f e2 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 53 e2
RSP: 0018:ffffc90004017680 EFLAGS: 00000293
RAX: ffffffff81b9b42d RBX: 1ffff110478c8121 RCX: ffff888104b50000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900040177c0 R08: ffffffff9011e3b7 R09: 1ffffffff2023c76
R10: dffffc0000000000 R11: fffffbfff2023c77 R12: ffff88823c640908
R13: dffffc0000000000 R14: ffff88812103bf00 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff88818de63000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f815abb6440 CR3: 000000000e54c000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80
 flush_tlb_mm_range+0x5d7/0x10e0
 tlb_flush_mmu+0x1af/0xa30
 tlb_finish_mmu+0xf9/0x230
 free_ldt_pgtables+0x19d/0x350
 exit_mmap+0x1af/0xa10
 __mmput+0x118/0x430
 exit_mm+0x168/0x220
 do_exit+0x8b9/0x2490
 do_group_exit+0x21b/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 x64_sys_call+0x221a/0x2240
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f815a6fca90
Code: Unable to access opcode bytes at 0x7f815a6fca66.
RSP: 002b:00007ffcd61c1838 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f815a7ed860 RCX: 00007f815a6fca90
RDX: 00000000000000e7 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00007f815a7ed860 R08: 00007ffcd61c1670 R09: 00007ffcd61c1770
R10: 00007ffcd61c16d0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f815a7f1658 R15: 0000000000000001
 </TASK>
