syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3003/1:b..l P14414/1:b..l
	(detected by 1, t=10502 jiffies, g=62033, q=93 ncpus=2)
task:syz-executor.0  state:R  running task     stack:27096 pid:14414 ppid:3584   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x142d/0x4550 kernel/sched/core.c:6558
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870
 irqentry_exit+0x53/0x80 kernel/entry/common.c:433
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:653
RIP: 0010:lock_acquire+0x26f/0x5a0 kernel/locking/lockdep.c:5666
Code: 2b 00 74 08 4c 89 f7 e8 af a2 77 00 f6 44 24 61 02 0f 85 84 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc90015a4f3e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92002b49e88 RCX: 1ffff92002b49e28
RDX: dffffc0000000000 RSI: ffffffff8aebf840 RDI: ffffffff8b3cf8c0
RBP: ffffc90015a4f528 R08: dffffc0000000000 R09: fffffbfff2091e45
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92002b49e84
R13: dffffc0000000000 R14: ffffc90015a4f440 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:306 [inline]
 rcu_read_lock include/linux/rcupdate.h:747 [inline]
 ext4_get_group_desc+0x12f/0x4b0 fs/ext4/balloc.c:284
 __ext4_get_inode_loc+0x263/0xe40 fs/ext4/inode.c:4479
 ext4_get_inode_loc fs/ext4/inode.c:4628 [inline]
 ext4_reserve_inode_write+0x17e/0x360 fs/ext4/inode.c:5858
 __ext4_mark_inode_dirty+0x1f2/0x920 fs/ext4/inode.c:6035
 add_dirent_to_buf+0x645/0x780 fs/ext4/namei.c:2213
 ext4_add_entry+0x796/0x1010 fs/ext4/namei.c:2448
 ext4_add_nondir+0x8d/0x290 fs/ext4/namei.c:2796
 ext4_symlink+0x91b/0xb40 fs/ext4/namei.c:3436
 vfs_symlink+0x247/0x3d0 fs/namei.c:4402
 do_symlinkat+0x21e/0x390 fs/namei.c:4431
 __do_sys_symlinkat fs/namei.c:4448 [inline]
 __se_sys_symlinkat fs/namei.c:4445 [inline]
 __x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4445
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f2188c7c467
RSP: 002b:00007ffe1a3ca808 EFLAGS: 00000206 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007ffe1a3ca8d0 RCX: 00007f2188c7c467
RDX: 00007f2188cc951b RSI: 00000000ffffff9c RDI: 00007f2188cc850e
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
task:udevd           state:R  running task     stack:22120 pid:3003  ppid:1      flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x142d/0x4550 kernel/sched/core.c:6558
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6727
 preempt_schedule+0xd9/0xe0 kernel/sched/core.c:6751
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x128/0x130 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:405 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x121/0x1c0 kernel/sched/wait.c:208
 sock_def_readable+0x15b/0x280 net/core/sock.c:3295
 __netlink_sendskb net/netlink/af_netlink.c:1273 [inline]
 netlink_sendskb+0x8e/0x120 net/netlink/af_netlink.c:1279
 netlink_unicast+0x394/0x970 net/netlink/af_netlink.c:1367
 netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1874
 sock_sendmsg_nosec net/socket.c:716 [inline]
 __sock_sendmsg net/socket.c:728 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2499
 ___sys_sendmsg net/socket.c:2553 [inline]
 __sys_sendmsg+0x2a9/0x390 net/socket.c:2582
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f45509a6a4b
RSP: 002b:00007ffeb9a432c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000055c2415dddf0 RCX: 00007f45509a6a4b
RDX: 0000000000000000 RSI: 00007ffeb9a432d8 RDI: 0000000000000004
RBP: 000055c2415eef70 R08: 0000000000000001 R09: 0000000000000000
R10: 000000000000010f R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000000b4 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 9370 jiffies! g62033 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=48629
rcu: rcu_preempt kthread starved for 9376 jiffies! g62033 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:25528 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x142d/0x4550 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1935
 rcu_gp_fqs_loop+0x2d2/0x1120 kernel/rcu/tree.c:1674
 rcu_gp_kthread+0xa3/0x3a0 kernel/rcu/tree.c:1873
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:572