rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=9774/1/0x4000000000000000 softirq=31257/31257 fqs=0
rcu: 	(detected by 0, t=10502 jiffies, g=18349, q=431 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6689 Comm: syz-executor 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:timerqueue_add+0x1df/0x200
Code: 4d 85 e4 40 0f 95 c5 eb 07 e8 9d 23 4a f6 31 ed 4c 89 e7 4c 89 f6 e8 40 65 ff ff 89 e8 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f <5d> c3 cc cc cc cc cc e8 75 23 4a f6 90 0f 0b 90 e9 6b fe ff ff 66
RSP: 0018:ffffc900001e0d30 EFLAGS: 00000082
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff888136627bd0 RDI: ffff888118753340
RBP: 0000000000000001 R08: ffff888118753357 R09: 0000000000000000
R10: ffff888118753340 R11: ffffed10230ea66b R12: ffff888118753340
R13: dffffc0000000000 R14: ffff888136627bd8 R15: ffff888136627b80
FS:  000055558122a500(0000) GS:ffff8881a3c1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555882bd808 CR3: 000000003f594000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 __hrtimer_run_queues+0x656/0xc60
 hrtimer_interrupt+0x45b/0xaa0
 __sysvec_apic_timer_interrupt+0x10b/0x410
 sysvec_apic_timer_interrupt+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70
Code: 89 fb e8 23 00 00 00 48 8b 3d c4 49 fe 0b 48 89 de 5b e9 73 98 58 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 8b 04 24 65 48 8b 0c 25 08 50 a0 92 65 8b 15 e8 a4
RSP: 0018:ffffc9000311f308 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000037b6c RCX: ffff88801ed43980
RDX: 0000000000000000 RSI: 0000000000037b6c RDI: 0000000400000000
RBP: ffffc9000311f630 R08: ffffea0000dedb07 R09: 1ffffd40001bdb60
R10: dffffc0000000000 R11: fffff940001bdb61 R12: dffffc0000000000
R13: ffff88803f425510 R14: 0000000000037b6c R15: 0000000000000001
 pfn_valid+0x473/0x490
 page_table_check_set+0x25/0x730
 copy_pmd_range+0x4439/0x71d0
 copy_page_range+0xc14/0x1270
 dup_mmap+0xf57/0x1ac0
 copy_mm+0x13c/0x4b0
 copy_process+0x1706/0x3c00
 kernel_clone+0x21e/0x840
 __x64_sys_clone+0x18b/0x1e0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f46ea585453
Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffe47435b48 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f46ea585453
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 000055558122a7d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 000000000001b552 R15: 00007ffe47435ce0
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g18349 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=6548
rcu: rcu_preempt kthread starved for 10502 jiffies! g18349 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
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:27432 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x12b/0x270
 rcu_gp_fqs_loop+0x301/0x1540
 rcu_gp_kthread+0x99/0x390
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
