syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3893/1:b..l P10028/2:b..l
	(detected by 1, t=10502 jiffies, g=58385, q=108 ncpus=2)
task:syz-executor.2  state:R  running task     stack:24984 pid:10028 ppid:9706   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:439
 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 cf aa 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:ffffc9000416eda0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff9200082ddc0 RCX: 1ffff9200082dd60
RDX: dffffc0000000000 RSI: ffffffff8aec13c0 RDI: ffffffff8b3d4520
RBP: ffffc9000416eef0 R08: dffffc0000000000 R09: fffffbfff2093a45
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff9200082ddbc
R13: dffffc0000000000 R14: ffffc9000416ee00 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 percpu_ref_tryget_many include/linux/percpu-refcount.h:241 [inline]
 percpu_ref_tryget+0x31/0x170 include/linux/percpu-refcount.h:266
 obj_cgroup_tryget include/linux/memcontrol.h:779 [inline]
 __get_obj_cgroup_from_memcg+0x70/0xe0 mm/memcontrol.c:3001
 get_obj_cgroup_from_current+0x170/0x280 mm/memcontrol.c:3021
 memcg_slab_pre_alloc_hook mm/slab.h:485 [inline]
 slab_pre_alloc_hook+0x90/0x300 mm/slab.h:715
 slab_alloc_node mm/slub.c:3318 [inline]
 __kmem_cache_alloc_node+0x47/0x260 mm/slub.c:3437
 __do_kmalloc_node mm/slab_common.c:954 [inline]
 __kmalloc_node+0xa2/0x230 mm/slab_common.c:962
 kmalloc_node include/linux/slab.h:582 [inline]
 kvmalloc_node+0x6e/0x180 mm/util.c:581
 kvmalloc include/linux/slab.h:709 [inline]
 kvzalloc include/linux/slab.h:717 [inline]
 alloc_netdev_mqs+0x85/0xeb0 net/core/dev.c:10623
 rtnl_create_link+0x2e9/0xa30 net/core/rtnetlink.c:3263
 rtnl_newlink_create net/core/rtnetlink.c:3380 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3610 [inline]
 rtnl_newlink+0x1403/0x2050 net/core/rtnetlink.c:3623
 rtnetlink_rcv_msg+0x818/0xff0 net/core/rtnetlink.c:6121
 netlink_rcv_skb+0x1cd/0x410 net/netlink/af_netlink.c:2508
 netlink_unicast_kernel net/netlink/af_netlink.c:1326 [inline]
 netlink_unicast+0x7d8/0x970 net/netlink/af_netlink.c:1352
 netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1874
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5a5/0x8f0 net/socket.c:2514
 ___sys_sendmsg net/socket.c:2568 [inline]
 __sys_sendmsg+0x2a9/0x390 net/socket.c:2597
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f059007cea9
RSP: 002b:00007f0590e880c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f05901b4050 RCX: 00007f059007cea9
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000005
RBP: 00007f05900ebff4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f05901b4050 R15: 00007ffd44d18b18
 </TASK>
task:kworker/u4:8    state:R  running task     stack:20928 pid:3893  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
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:439
 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 cf aa 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: 0000:ffffc900054dfa20 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92000a9bf50 RCX: 1ffff92000a9bef0
RDX: dffffc0000000000 RSI: ffffffff8aec13c0 RDI: ffffffff8b3d4520
RBP: ffffc900054dfb70 R08: dffffc0000000000 R09: fffffbfff2093a45
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000a9bf4c
R13: dffffc0000000000 R14: ffffc900054dfa80 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 batadv_nc_process_nc_paths+0xd6/0x390 net/batman-adv/network-coding.c:687
 batadv_nc_worker+0x426/0x610 net/batman-adv/network-coding.c:728
 process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>
rcu: rcu_preempt kthread starved for 10261 jiffies! g58385 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:26136 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:1965
 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </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