syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6585/1:b..l P6590/1:b..l
	(detected by 0, t=10502 jiffies, g=23005, q=15 ncpus=2)
task:syz.0.592       state:R  running task     stack:25312 pid:6590  ppid:4274   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730
 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x11b/0x180 kernel/sched/wait.c:208
 sock_def_readable+0x15b/0x280 net/core/sock.c:3313
 __netlink_sendskb net/netlink/af_netlink.c:1264 [inline]
 netlink_broadcast_deliver net/netlink/af_netlink.c:1399 [inline]
 do_one_broadcast net/netlink/af_netlink.c:1479 [inline]
 netlink_broadcast+0xcea/0x10d0 net/netlink/af_netlink.c:1519
 uevent_net_broadcast_untagged lib/kobject_uevent.c:331 [inline]
 kobject_uevent_net_broadcast+0x364/0x530 lib/kobject_uevent.c:409
 kobject_uevent_env+0x54c/0x8a0 lib/kobject_uevent.c:608
 loop_configure+0xece/0x1230 drivers/block/loop.c:1109
 lo_ioctl+0x82b/0x1bf0 drivers/block/loop.c:-1
 blkdev_ioctl+0x37b/0x700 block/ioctl.c:620
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 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: 0033:0x7fa61f58f34b
RSP: 002b:00007fa6203badc0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fa61f58f34b
RDX: 0000000000000003 RSI: 0000000000004c00 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000000004f6
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007fa6203baef0 R14: 00007fa6203baeb0 R15: 00007fa6153f7000
 </TASK>
task:syz.3.588       state:R  running task     stack:24160 pid:6585  ppid:4275   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:lock_is_held_type+0x13a/0x190 kernel/locking/lockdep.c:5710
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc90004a0f730 EFLAGS: 00000206
RAX: 7931ec8a8e5e3800 RBX: ffff888029c8bb80 RCX: 7931ec8a8e5e3800
RDX: ffff888029c8bb80 RSI: ffffffff8a8c1700 RDI: ffffffff8adef760
RBP: 0000000000000001 R08: ffff888029c8bb80 R09: 0000000000000002
R10: 0000000000000003 R11: 0000000000000002 R12: 0000000000000001
R13: 0000000000000246 R14: ffffffff8cb2aca0 R15: ffff888029c8c688
 xa_entry include/linux/xarray.h:1198 [inline]
 xas_descend+0x129/0x490 lib/xarray.c:204
 xas_load lib/xarray.c:242 [inline]
 xas_find+0x1e0/0xab0 lib/xarray.c:1252
 first_map_page mm/filemap.c:3418 [inline]
 filemap_map_pages+0x245/0x10d0 mm/filemap.c:3445
 do_fault_around mm/memory.c:4600 [inline]
 do_read_fault mm/memory.c:4626 [inline]
 do_fault mm/memory.c:4760 [inline]
 handle_pte_fault mm/memory.c:5031 [inline]
 __handle_mm_fault mm/memory.c:5173 [inline]
 handle_mm_fault+0x287e/0x3e60 mm/memory.c:5294
 faultin_page mm/gup.c:1026 [inline]
 __get_user_pages+0x3ff/0xeb0 mm/gup.c:1250
 populate_vma_page_range+0x214/0x2b0 mm/gup.c:1607
 __mm_populate+0x248/0x370 mm/gup.c:1721
 mm_populate include/linux/mm.h:2891 [inline]
 vm_mmap_pgoff+0x203/0x2b0 mm/util.c:525
 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: 0033:0x7fdd12f8f749
RSP: 002b:00007fdd111f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fdd131e6180 RCX: 00007fdd12f8f749
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007fdd13013f91 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdd131e6218 R14: 00007fdd131e6180 R15: 00007ffd4d22c778
 </TASK>
rcu: rcu_preempt kthread starved for 10560 jiffies! g23005 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:27008 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:2167
 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:741