INFO: rcu detected stall in userfaultfd

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-5.15	INFO: rcu detected stall in userfaultfd_ioctl				1	105d	105d	0/3	auto-obsoleted due to no activity on 2024/10/12 17:09
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1):
 P10228/1:b..l

rcu: 	(detected by 0, t=10502 jiffies, g=61549, q=618 ncpus=2)
task:syz-executor.1  state:R
  running task     stack:22960 pid:10228 tgid:10225 ppid:9957   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x1796/0x49d0 kernel/sched/core.c:6745
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:7067
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:trace_lock_acquire include/trace/events/lock.h:24 [inline]
RIP: 0010:lock_acquire+0xde/0x550 kernel/locking/lockdep.c:5725
Code: 83 f4 02 00 00 89 c3 48 89 d8 48 c1 e8 06 48 8d 3c c5 a8 1e ac 8f be 08 00 00 00 e8 9c 3e 86 00 48 0f a3 1d bc b9 39 0e 73 16 <e8> 3d f1 09 00 84 c0 75 0d 80 3d 90 31 24 0e 00 0f 84 f9 02 00 00
RSP: 0018:ffffc9000376efc0 EFLAGS: 00000257

RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff817264e4
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8fac1ea8
RBP: ffffc9000376f108 R08: ffffffff8fac1eaf R09: 1ffffffff1f583d5
R10: dffffc0000000000 R11: fffffbfff1f583d6 R12: 1ffff920006ede00
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc9000376f220
 rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 rcu_read_lock include/linux/rcupdate.h:781 [inline]
 __pte_offset_map+0x9e/0x380 mm/pgtable-generic.c:287
 pte_offset_map_nolock+0xad/0x1f0 mm/pgtable-generic.c:314
 move_pages_pte+0x35a/0x33d0 mm/userfaultfd.c:1152
 move_pages+0xe26/0x1560 mm/userfaultfd.c:1733
 userfaultfd_move fs/userfaultfd.c:2016 [inline]
 userfaultfd_ioctl+0x5c0d/0x7160 fs/userfaultfd.c:2134
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe08147cea9
RSP: 002b:00007fe0822600c8 EFLAGS: 00000246
 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe0815b4050 RCX: 00007fe08147cea9
RDX: 0000000020000080 RSI: 00000000c028aa05 RDI: 0000000000000005
RBP: 00007fe0814ebff4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fe0815b4050 R15: 00007ffc6d23e6c8
 </TASK>
rcu: rcu_preempt kthread starved for 680 jiffies! g61549 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:26448 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x1796/0x49d0 kernel/sched/core.c:6745
 __schedule_loop kernel/sched/core.c:6822 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6837
 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2000
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2202
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:72 [inline]
RIP: 0010:acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:113
Code: 90 90 90 90 90 90 90 90 90 65 48 8b 04 25 c0 d4 03 00 48 f7 00 08 00 00 00 75 10 66 90 0f 00 2d e5 9f aa 00 f3 0f 1e fa fb f4 <fa> c3 cc cc cc cc 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90
RSP: 0018:ffffffff8e007ca8 EFLAGS: 00000246

RAX: ffffffff8e094680 RBX: ffff88801b6f9864 RCX: 00000000001ec469
RDX: 0000000000000001 RSI: ffff88801b6f9800 RDI: ffff88801b6f9864
RBP: 000000000003a578 R08: ffff8880b9437d0b R09: 1ffff11017286fa1
R10: dffffc0000000000 R11: ffffffff8b7e0a30 R12: ffff8880183a6000
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8eabbd00
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb43038ed90 CR3: 0000000057fd8000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 </IRQ>
 <TASK>
 acpi_idle_enter+0xe4/0x140 drivers/acpi/processor_idle.c:707
 cpuidle_enter_state+0x112/0x480 drivers/cpuidle/cpuidle.c:267
 cpuidle_enter+0x5d/0xa0 drivers/cpuidle/cpuidle.c:388
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:236 [inline]
 do_idle+0x375/0x5d0 kernel/sched/idle.c:332
 cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:430
 rest_init+0x2dc/0x300 init/main.c:747
 start_kernel+0x47a/0x500 init/main.c:1103
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:488
 common_startup_64+0x13e/0x147
 </TASK>