syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4821/1:b..l P4602/1:b..l
	(detected by 0, t=10502 jiffies, g=32137, q=97 ncpus=2)
task:udevd           state:R  running task     stack:23904 pid:4602  ppid:3623   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 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:ma_gaps lib/maple_tree.c:652 [inline]
RIP: 0010:mas_validate_gaps lib/maple_tree.c:6968 [inline]
RIP: 0010:mt_validate+0x2b18/0x4c90 lib/maple_tree.c:7241
Code: 83 83 f7 4c 8b b4 24 38 01 00 00 4d 89 f5 49 81 e5 00 ff ff ff 41 c1 ee 03 41 83 e6 0f bf 03 00 00 00 44 89 f6 e8 a8 86 83 f7 <83> 7c 24 18 03 75 3a 41 83 fe 03 73 75 e8 36 83 83 f7 44 89 f0 48
RSP: 0018:ffffc900057af720 EFLAGS: 00000293
RAX: ffffffff89fd5328 RBX: ffff88807d37a210 RCX: 0000000000000000
RDX: ffff88802ff9bb80 RSI: 0000000000000001 RDI: 0000000000000003
RBP: ffffc900057af8f0 R08: ffff88802ff9bb80 R09: 0000000000000004
R10: 0000000000000003 R11: 0000000000000000 R12: 00007fad4797dfff
R13: ffff88807d37a200 R14: 0000000000000001 R15: 0000000000000001
 validate_mm_mt+0xcd/0x420 mm/mmap.c:294
 validate_mm+0xcc/0x2b0 mm/mmap.c:331
 do_mas_align_munmap+0xfad/0x1220 mm/mmap.c:2587
 do_mas_munmap+0x240/0x2b0 mm/mmap.c:2638
 __vm_munmap+0x18d/0x290 mm/mmap.c:2924
 __do_sys_munmap mm/mmap.c:2949 [inline]
 __se_sys_munmap mm/mmap.c:2946 [inline]
 __x64_sys_munmap+0x5c/0x70 mm/mmap.c:2946
 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: 0033:0x7fad4731e097
RSP: 002b:00007fffe7deda88 EFLAGS: 00000246 ORIG_RAX: 000000000000000b
RAX: ffffffffffffffda RBX: 0000561a4caaa430 RCX: 00007fad4731e097
RDX: 0000561a4cab6788 RSI: 0000000000000200 RDI: 00007fad4797e000
RBP: 000000000000001a R08: 0000000000000040 R09: 0000000000000003
R10: 0000000000000040 R11: 0000000000000246 R12: 0000561a4cad1510
R13: 00007fad47ac739c R14: 0000000000003400 R15: 0000000000000009
 </TASK>
task:kworker/u4:19   state:R  running task     stack:20448 pid:4821  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 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:ffffc90005b87ac0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ca47f42e83386900
RDX: 0000000000000000 RSI: ffffffff8a6c1160 RDI: ffffffff8abf1360
RBP: ffffc90005b87bc8 R08: dffffc0000000000 R09: fffffbfff2117049
R10: fffffbfff2117049 R11: 1ffffffff2117048 R12: 0000000000000001
R13: 1ffff92000b70f64 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 10499 jiffies! g32137 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=17802
rcu: rcu_preempt kthread starved for 10500 jiffies! g32137 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </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:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:735