rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=4a54/1/0x4000000000000000 softirq=56929/56933 fqs=92
rcu: 	(detected by 1, t=10502 jiffies, g=46693, q=513 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 15 Comm: ksoftirqd/0 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:mm_get_cid+0xab/0x130
Code: 41 5c 41 5d 41 5e 41 5f 5d e9 91 28 cb 09 cc 49 c7 c5 c8 04 9b 8d 49 c1 ed 03 bd 00 00 00 80 eb 07 44 89 f0 f7 d8 71 d4 f3 90 <43> 0f b6 44 25 00 84 c0 75 41 44 8b 3d cc 41 08 0c 48 89 df 4c 89
RSP: 0018:ffffc90000147a28 EFLAGS: 00000887
RAX: 0000000080000000 RBX: ffff8881b6f2c8d0 RCX: dffffc0000000000
RDX: 0000000000000002 RSI: 0000000000000002 RDI: ffff8881b6f2c8d0
RBP: 0000000080000000 R08: ffff8881b6f2c753 R09: 1ffff11036de58ea
R10: dffffc0000000000 R11: ffffed1036de58eb R12: dffffc0000000000
R13: 1ffffffff1b36099 R14: 0000000080000000 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff88818e83a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8276e55fc8 CR3: 00000001b3f4c000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __schedule+0x2169/0x5000
 schedule+0x165/0x360
 smpboot_thread_fn+0x5bd/0xa60
 kthread+0x711/0x8a0
 ret_from_fork+0x599/0xb30
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: rcu_preempt kthread starved for 10318 jiffies! g46693 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:27392 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x14bc/0x5000
 schedule+0x165/0x360
 schedule_timeout+0x12b/0x270
 rcu_gp_fqs_loop+0x301/0x1540
 rcu_gp_kthread+0x99/0x390
 kthread+0x711/0x8a0
 ret_from_fork+0x599/0xb30
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 36 Comm: kworker/u10:1 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
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:smp_call_function_many_cond+0xccf/0x12b0
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 1a 9a 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 c5 95 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 a9 95
RSP: 0018:ffffc90000ac60e0 EFLAGS: 00000293
RAX: ffffffff81b61b07 RBX: 1ffff1102420856d RCX: ffff888161ef0000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000ac6260 R08: ffff88811328c8c7 R09: 1ffff11022651918
R10: dffffc0000000000 R11: ffffffff817637d0 R12: ffff888121042b68
R13: dffffc0000000000 R14: ffff88823c63bb00 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8882a9e3a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000101728000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80
 flush_tlb_mm_range+0x6b1/0x1280
 ptep_clear_flush+0x120/0x170
 page_vma_mkclean_one+0x401/0x790
 page_mkclean_one+0x1c0/0x280
 __rmap_walk_file+0x467/0x620
 folio_mkclean+0x297/0x390
 folio_clear_dirty_for_io+0x1a5/0x710
 mpage_submit_folio+0x86/0x2b0
 mpage_process_page_bufs+0x6d5/0x8e0
 mpage_prepare_extent_to_map+0xdcc/0x1660
 ext4_do_writepages+0xb74/0x4500
 ext4_writepages+0x203/0x350
 do_writepages+0x32e/0x550
 __writeback_single_inode+0x133/0x1240
 writeback_sb_inodes+0x93a/0x1870
 __writeback_inodes_wb+0x111/0x240
 wb_writeback+0x43f/0xaa0
 wb_workfn+0xad2/0xed0
 process_scheduled_works+0xad1/0x1770
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x599/0xb30
 ret_from_fork_asm+0x1a/0x30
 </TASK>
