syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4389/1:b..l P4284/1:b..l
	(detected by 1, t=10502 jiffies, g=12785, q=51 ncpus=2)
task:udevd           state:R  running task     stack:24128 pid:4284  ppid:3637   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:212
Code: 2e 0f 1f 84 00 00 00 00 00 90 53 48 89 fb e8 17 00 00 00 48 8b 3d 90 30 7e 0c 48 89 de 5b e9 47 68 4f 00 00 00 cc cc 00 00 cc <48> 8b 04 24 65 48 8b 0d 64 8f 81 7e 65 8b 15 65 8f 81 7e 81 e2 00
RSP: 0018:ffffc900041778d8 EFLAGS: 00000287
RAX: ffffffff89fe2456 RBX: 0000000000000003 RCX: ffff88805b655940
RDX: 0000000000000000 RSI: 00007f99b860dfff RDI: 00007f99b860afff
RBP: ffffc90004177ab0 R08: ffff88805b655940 R09: 0000000000000003
R10: 0000000000000003 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff88802422d880 R14: 00007f99b860afff R15: 00007f99b860dfff
 mas_validate_limits lib/maple_tree.c:7135 [inline]
 mt_validate+0x1c54/0x4c90 lib/maple_tree.c:7244
 validate_mm_mt+0xcd/0x420 mm/mmap.c:295
 validate_mm+0xcc/0x2b0 mm/mmap.c:332
 do_mmap+0xc7/0xfd0 mm/mmap.c:1270
 vm_mmap_pgoff+0x1b2/0x2b0 mm/util.c:520
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f99b7f1d822
RSP: 002b:00007fffcf30cb58 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f99b7f1d822
RDX: 0000000000000003 RSI: 0000000000000200 RDI: 0000000000000000
RBP: 0000000000000022 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000000038
R13: 0000000000000400 R14: 0000561a372c80b0 R15: 000000000000fe00
 </TASK>
task:kworker/u4:8    state:R  running task     stack:24440 pid:4389  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc90002e87ac0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: a0099b48692eb200
RDX: 0000000000000000 RSI: ffffffff8a6c1780 RDI: ffffffff8abef920
RBP: ffffc90002e87bc8 R08: dffffc0000000000 R09: fffffbfff2119049
R10: fffffbfff2119049 R11: 1ffffffff2119048 R12: 0000000000000000
R13: 1ffff920005d0f64 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0xeb/0x600 net/batman-adv/network-coding.c:719
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10552 jiffies! g12785 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=4561
rcu: rcu_preempt kthread starved for 10553 jiffies! g12785 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:27000 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>