syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4468/1:b..l
	(detected by 0, t=10502 jiffies, g=4557, q=150 ncpus=2)
task:syz.3.32        state:R  running task     stack:0     pid:4468  ppid:4315   flags:0x00000008
Call trace:
 __switch_to+0x320/0x754 arch/arm64/kernel/process.c:553
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0xef4/0x1d44 kernel/sched/core.c:6558
 preempt_schedule_irq+0x8c/0x1b8 kernel/sched/core.c:6870
 arm64_preempt_schedule_irq arch/arm64/kernel/entry-common.c:265 [inline]
 __el1_irq arch/arm64/kernel/entry-common.c:474 [inline]
 el1_interrupt+0x4c/0x68 arch/arm64/kernel/entry-common.c:486
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491
 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581
 arch_local_irq_restore+0x8/0x10 arch/arm64/include/asm/irqflags.h:122
 lock_is_held include/linux/lockdep.h:283 [inline]
 rcu_read_lock_held+0x34/0x50 kernel/rcu/update.c:311
 xa_head include/linux/xarray.h:1182 [inline]
 xas_start+0x260/0x6c4 lib/xarray.c:188
 xas_load lib/xarray.c:235 [inline]
 xas_find+0x124/0x8f0 lib/xarray.c:1252
 first_map_page mm/filemap.c:3389 [inline]
 filemap_map_pages+0x248/0x12f0 mm/filemap.c:3416
 do_fault_around mm/memory.c:4598 [inline]
 do_read_fault mm/memory.c:4624 [inline]
 do_fault mm/memory.c:4758 [inline]
 handle_pte_fault mm/memory.c:5029 [inline]
 __handle_mm_fault mm/memory.c:5171 [inline]
 handle_mm_fault+0x248c/0x3d38 mm/memory.c:5292
 faultin_page mm/gup.c:1009 [inline]
 __get_user_pages+0x3b0/0x968 mm/gup.c:1233
 populate_vma_page_range+0x1fc/0x2a0 mm/gup.c:1590
 __mm_populate+0x240/0x3d8 mm/gup.c:1704
 mm_populate include/linux/mm.h:2801 [inline]
 vm_mmap_pgoff+0x1fc/0x2b4 mm/util.c:525
 ksys_mmap_pgoff+0xd0/0x5b0 mm/mmap.c:1471
 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
 __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
 __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
rcu: rcu_preempt kthread starved for 10505 jiffies! g4557 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:0     pid:16    ppid:2      flags:0x00000008
Call trace:
 __switch_to+0x320/0x754 arch/arm64/kernel/process.c:553
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0xef4/0x1d44 kernel/sched/core.c:6558
 schedule+0xc4/0x170 kernel/sched/core.c:6634
 schedule_timeout+0x1d8/0x344 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2cc/0x1538 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xc0/0x308 kernel/rcu/tree.c:1905
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:864
rcu: Stack dump where RCU GP kthread last ran:
Task dump for CPU 1:
task:syz.1.26        state:R  running task     stack:0     pid:4491  ppid:4313   flags:0x00000001
Call trace:
 __switch_to+0x320/0x754 arch/arm64/kernel/process.c:553
 0xffff0000d3ab5db8