rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=42bc/1/0x4000000000000000 softirq=20551/20557 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5926/1:b..l
rcu: 	(detected by 0, t=10505 jiffies, g=11513, q=407 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6954 Comm: syz.0.250 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:lock_acquire+0x70/0x360
Code: f8 08 0f 83 b8 01 00 00 89 c0 48 0f a3 05 78 28 06 0e 73 16 e8 61 02 09 00 84 c0 75 0d f6 05 97 0e f0 0d 01 0f 84 d7 01 00 00 <83> 3d 99 59 06 0e 00 0f 84 f0 00 00 00 48 8b b4 24 90 00 00 00 4c
RSP: 0000:ffffc900001e0b40 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 4854992fc278a700
RDX: 0000000000000000 RSI: ffffffff8be33660 RDI: ffffffff8be33620
RBP: ffffffff84d0252b R08: 0000000000000001 R09: 0000000000000000
R10: ffffc900001e0ca0 R11: fffff5200003c196 R12: 0000000000000000
R13: ffffffff99cc6908 R14: 0000000000000000 R15: 0000000000000001
FS:  000055556d469500(0000) GS:ffff8881a3c1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31a63fff CR3: 0000000105f0e000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 _raw_spin_lock_irqsave+0xa7/0xf0
 debug_object_activate+0xbb/0x420
 enqueue_hrtimer+0x30/0x3a0
 __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_const_cmp4+0x31/0x90
Code: 24 65 48 8b 14 25 08 50 a0 92 65 8b 0d a8 a0 e0 10 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba 3c 16 00 00 00 74 52 <8b> 8a 18 16 00 00 83 f9 03 75 47 48 8b 8a 20 16 00 00 44 8b 8a 1c
RSP: 0000:ffffc90006ec78a0 EFLAGS: 00000246
RAX: ffffffff82746b13 RBX: 1ffff110045d5652 RCX: 0000000000000000
RDX: ffff888020440000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00000000fffffffb R08: ffff88801dde665f R09: 1ffff11003bbcccb
R10: dffffc0000000000 R11: ffffed1003bbcccc R12: ffff888022eab290
R13: 0000000000000000 R14: ffff888022eab268 R15: dffffc0000000000
 ext4_reserve_inode_write+0x1e3/0x360
 __ext4_mark_inode_dirty+0x15b/0x700
 ext4_dirty_inode+0xd0/0x110
 __mark_inode_dirty+0x2ec/0xe10
 file_update_time+0x40c/0x490
 ext4_page_mkwrite+0x20e/0x1190
 do_page_mkwrite+0x14d/0x310
 __handle_mm_fault+0x1916/0x5440
 handle_mm_fault+0x40a/0x8e0
 do_user_addr_fault+0xa81/0x1390
 exc_page_fault+0x76/0xf0
 asm_exc_page_fault+0x26/0x30
RIP: 0033:0x7fcd7fe61051
Code: 55 5a ff ff 48 8b 05 26 47 e8 00 0f b6 4c 24 10 be 08 00 00 00 48 89 df 83 05 02 47 e8 00 01 48 8d 50 ff 48 89 15 07 47 e8 00 <88> 48 ff 8b 2d ee 46 e8 00 e8 21 5a ff ff 48 8b 05 fa 46 e8 00 41
RSP: 002b:00007ffe0a2f05d0 EFLAGS: 00010202
RAX: 0000001b31a64000 RBX: 00007fcd80ce5720 RCX: 0000000000000007
RDX: 0000001b31a63fff RSI: 0000000000000008 RDI: 00007fcd80ce5720
RBP: 00007fcd801b6038 R08: 0000000000000000 R09: 0000000000000002
R10: 00007fcd80ce5700 R11: 0000000000000001 R12: 0000000000000007
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
task:udevd           state:R  running task     stack:25448 pid:5926  tgid:5926  ppid:5293   task_flags:0x400140 flags:0x00004002
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 preempt_schedule_common+0x83/0xd0
 preempt_schedule+0xae/0xc0
 preempt_schedule_thunk+0x16/0x30
 _raw_spin_unlock_irqrestore+0xfd/0x110
 __wake_up_common_lock+0x190/0x1f0
 sock_def_readable+0x1fb/0x550
 unix_dgram_sendmsg+0xe08/0x1850
 __sock_sendmsg+0x21c/0x270
 sock_write_iter+0x258/0x330
 vfs_write+0x5c9/0xb30
 ksys_write+0x145/0x250
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0770d16bf2
RSP: 002b:00007ffc73651228 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0770d16bf2
RDX: 0000000000000000 RSI: 00007ffc7365127f RDI: 000000000000000a
RBP: 00007ffc7365127f R08: 0000000000000001 R09: 0000000000000000
R10: 000000000000010f R11: 0000000000000246 R12: 000000000000000a
R13: 00007f0771091ae0 R14: 0000000000000000 R15: 0000559eebee4910
 </TASK>
rcu: rcu_preempt kthread starved for 10505 jiffies! g11513 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:27496 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>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 6956 Comm: syz.0.250 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:__sanitizer_cov_trace_pc+0x5d/0x70
Code: 18 16 00 00 83 fa 02 75 21 48 8b 91 20 16 00 00 48 8b 32 48 8d 7e 01 8b 89 1c 16 00 00 48 39 cf 73 08 48 89 3a 48 89 44 f2 08 <e9> 8e af bc 09 cc 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90
RSP: 0018:ffffc9000621fa78 EFLAGS: 00000293
RAX: ffffffff81b44ceb RBX: 1ffff11026cc7f61 RCX: ffff8881074cb980
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000621fbf0 R08: ffffffff8fa38337 R09: 1ffffffff1f47066
R10: dffffc0000000000 R11: ffffffff81705100 R12: ffff88813663fb08
R13: dffffc0000000000 R14: ffff88804b03b1c0 R15: 0000000000000001
FS:  00007fcd80d2b6c0(0000) GS:ffff8880b861b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcd801b20b8 CR3: 0000000105f0e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 smp_call_function_many_cond+0xd4b/0x12d0
 clock_was_set+0x709/0x7c0
 do_settimeofday64+0x41d/0x630
 __x64_sys_clock_settime+0x22c/0x280
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcd7ff8ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcd80d2b038 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3
RAX: ffffffffffffffda RBX: 00007fcd801b6090 RCX: 00007fcd7ff8ebe9
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000000
RBP: 00007fcd80011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcd801b6128 R14: 00007fcd801b6090 R15: 00007ffe0a2f0528
 </TASK>
