syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4735/1:b..l
	(detected by 1, t=10502 jiffies, g=10253, q=251 ncpus=2)
task:sed             state:R  running task     stack:24352 pid:4735  ppid:4734   flags:0x00004000
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:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x7b/0x290 mm/kasan/generic.c:189
Code: 5c 37 ff 48 c1 eb 03 4e 8d 14 3b 4d 89 d6 4d 29 ce 49 83 fe 10 7f 26 4d 85 f6 0f 84 39 01 00 00 48 f7 d3 4c 01 db 41 80 39 00 <0f> 85 c1 01 00 00 49 ff c1 48 ff c3 75 ee e9 1c 01 00 00 44 89 cb
RSP: 0018:ffffc900034ef180 EFLAGS: 00000202
RAX: 0000000000000001 RBX: ffffffffffffffff RCX: ffffffff8a03c68e
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff97053000
RBP: ffffc900034ef370 R08: dffffc0000000000 R09: fffffbfff2e0a600
R10: fffffbfff2e0a601 R11: 1ffffffff2e0a600 R12: 0000000000000003
R13: ffff88802995bc00 R14: 0000000000000001 R15: dffffc0000000001
 instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
 atomic_inc include/linux/atomic/atomic-instrumented.h:190 [inline]
 mas_validate_parent_slot lib/maple_tree.c:7046 [inline]
 mt_validate+0xdfe/0x4c90 lib/maple_tree.c:7240
 validate_mm_mt+0xcd/0x420 mm/mmap.c:294
 validate_mm+0xcc/0x2b0 mm/mmap.c:331
 __vma_adjust+0x17bf/0x1c50 mm/mmap.c:878
 vma_adjust include/linux/mm.h:2745 [inline]
 __split_vma+0x3a7/0x500 mm/mmap.c:-1
 do_mas_align_munmap+0x762/0x1220 mm/mmap.c:2497
 do_mas_munmap+0x240/0x2b0 mm/mmap.c:2646
 __mmap_region mm/mmap.c:2694 [inline]
 mmap_region+0x713/0x1d30 mm/mmap.c:2912
 do_mmap+0x894/0xf30 mm/mmap.c:1432
 vm_mmap_pgoff+0x1b2/0x2b0 mm/util.c:520
 ksys_mmap_pgoff+0x516/0x6f0 mm/mmap.c:1478
 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: 0033:0x7f2105c69242
RSP: 002b:00007ffe4c115318 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f210598f000 RCX: 00007f2105c69242
RDX: 0000000000000001 RSI: 0000000000001000 RDI: 00007f210598f000
RBP: 0000000000000812 R08: 0000000000000003 R09: 0000000000004000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffe4c1153a0
R13: 00007f2105c46050 R14: 00007ffe4c115750 R15: 00000fffc9822a66
 </TASK>
rcu: rcu_preempt kthread starved for 9316 jiffies! g10253 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:27464 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 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 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 default_idle+0xb/0x10 arch/x86/kernel/process.c:741