syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4270/1:b..l P6541/1:b..l
rcu: 	(detected by 0, t=10504 jiffies, g=37705, q=672 ncpus=2)
task:syz.4.157       state:R  running task     stack:26480 pid:6541  tgid:6541  ppid:6315   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0xe37/0x5490 kernel/sched/core.c:6529
 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:6708
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 zap_pte_range mm/memory.c:1688 [inline]
 zap_pmd_range mm/memory.c:1736 [inline]
 zap_pud_range mm/memory.c:1765 [inline]
 zap_p4d_range mm/memory.c:1786 [inline]
 unmap_page_range+0x1ca6/0x3d30 mm/memory.c:1807
 unmap_single_vma+0x194/0x2b0 mm/memory.c:1853
 unmap_vmas+0x22f/0x490 mm/memory.c:1897
 exit_mmap+0x1b8/0xb20 mm/mmap.c:3412
 __mmput+0x12a/0x480 kernel/fork.c:1345
 mmput+0x62/0x70 kernel/fork.c:1367
 exit_mm kernel/exit.c:571 [inline]
 do_exit+0x9bf/0x2bb0 kernel/exit.c:869
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1031
 get_signal+0x25fb/0x2770 kernel/signal.c:2917
 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 irqentry_exit_to_user_mode+0x13f/0x280 kernel/entry/common.c:231
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707
RIP: 0033:0x7f9e07c556a0
RSP: 002b:00007ffd8c3bf890 EFLAGS: 00000297
RAX: 00007f9e064ccb58 RBX: 00007f9e064cab08 RCX: ffffffff813d00b7
RDX: ffffffff813d00cf RSI: ffffffff813d00cf RDI: 00007f9e064decf0
RBP: 00007f9e064ab568 R08: 00007f9e064c5128 R09: 00007f9e07f22000
R10: 00000000813cfec6 R11: 00000000000000ff R12: 00007f9e064ab560
R13: 000000000000001c R14: 00007f9e06201008 R15: ffffffffffffffff
 </TASK>
task:kworker/u8:11   state:R  running task     stack:23552 pid:4270  tgid:4270  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_mcast_mla_update
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0xe37/0x5490 kernel/sched/core.c:6529
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:6851
 irqentry_exit+0x36/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__kernel_text_address+0x0/0x40 kernel/extable.c:78
Code: 5b c3 cc cc cc cc 48 c7 c7 44 55 1d 90 e8 c8 63 92 00 e9 6a ff ff ff 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <66> 0f 1f 00 53 48 89 fb e8 e3 fe ff ff 85 c0 75 1b 48 81 fb 00 b0
RSP: 0018:ffffc9000be57770 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: ffffc9000be577a0 RCX: ffffffff813cf86c
RDX: 1ffff920017caefd RSI: ffffffff813cf888 RDI: ffffffff81568b95
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffc9000be577e8
R13: ffffffff817774c0 R14: ffffc9000be57860 R15: ffff8880345e3c00
 unwind_get_return_address+0x7c/0xe0 arch/x86/kernel/unwind_orc.c:369
 arch_stack_walk+0xc1/0x170 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x95/0xd0 kernel/stacktrace.c:122
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:387
 kmalloc_noprof include/linux/slab.h:690 [inline]
 batadv_mcast_mla_softif_get_ipv6 net/batman-adv/multicast.c:478 [inline]
 batadv_mcast_mla_softif_get net/batman-adv/multicast.c:536 [inline]
 __batadv_mcast_mla_update net/batman-adv/multicast.c:912 [inline]
 batadv_mcast_mla_update+0x1908/0x3200 net/batman-adv/multicast.c:949
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3393
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: rcu_preempt kthread starved for 10560 jiffies! g37705 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:26064 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0xe37/0x5490 kernel/sched/core.c:6529
 __schedule_loop kernel/sched/core.c:6606 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6621
 schedule_timeout+0x136/0x2a0 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2034
 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2236
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:111