syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P14233/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=96961, q=585 ncpus=2)
task:syz.0.1771      state:R  running task     stack:27088 pid:14233 tgid:14229 ppid:13520  flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0xe37/0x5490 kernel/sched/core.c:6529
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:6851
 irqentry_exit+0x36/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:209
Code: be b0 01 00 00 e8 a0 ff ff ff 31 c0 c3 cc cc cc cc 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 65 48 8b 15 e4 64 79 7e 65 8b 05 e5 64 79 7e a9 00 01
RSP: 0018:ffffc900033d7548 EFLAGS: 00000202
RAX: ffffffff81f1bb74 RBX: ffffea00011a6200 RCX: ffffffff81f1bb8a
RDX: ffff8880213cda00 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000003 R14: 0000000000000001 R15: 0000000000000000
 rcu_read_lock include/linux/rcupdate.h:839 [inline]
 page_ext_get+0x1d2/0x310 mm/page_ext.c:525
 __page_table_check_zero+0xcd/0x370 mm/page_table_check.c:148
 page_table_check_alloc include/linux/page_table_check.h:33 [inline]
 post_alloc_hook+0x2c0/0x350 mm/page_alloc.c:1494
 prep_new_page mm/page_alloc.c:1501 [inline]
 get_page_from_freelist+0x1351/0x2e50 mm/page_alloc.c:3439
 __alloc_pages_noprof+0x22b/0x2460 mm/page_alloc.c:4695
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x4e/0xf0 mm/slub.c:2321
 allocate_slab mm/slub.c:2484 [inline]
 new_slab+0x84/0x260 mm/slub.c:2537
 ___slab_alloc+0xdac/0x1870 mm/slub.c:3723
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3813
 __slab_alloc_node mm/slub.c:3866 [inline]
 slab_alloc_node mm/slub.c:4025 [inline]
 __do_kmalloc_node mm/slub.c:4157 [inline]
 __kmalloc_node_noprof+0x357/0x430 mm/slub.c:4164
 __kvmalloc_node_noprof+0x9d/0x1a0 mm/util.c:650
 ceph_msg_new2+0x29f/0x4f0 net/ceph/messenger.c:1982
 msgpool_alloc+0xa8/0x1c0 net/ceph/msgpool.c:17
 mempool_init_node+0x31e/0x760 mm/mempool.c:217
 mempool_create_node_noprof+0xd0/0x190 mm/mempool.c:280
 ceph_msgpool_init+0xdc/0x1a0 net/ceph/msgpool.c:46
 ceph_osdc_init+0x539/0x9e0 net/ceph/osd_client.c:5281
 ceph_create_client net/ceph/ceph_common.c:745 [inline]
 ceph_create_client+0x27e/0x370 net/ceph/ceph_common.c:707
 create_fs_client fs/ceph/super.c:818 [inline]
 ceph_get_tree+0x1ac/0x1e10 fs/ceph/super.c:1310
 vfs_get_tree+0x8f/0x380 fs/super.c:1800
 vfs_cmd_create+0xd7/0x2a0 fs/fsopen.c:226
 vfs_fsconfig_locked fs/fsopen.c:290 [inline]
 __do_sys_fsconfig+0x88e/0xbe0 fs/fsopen.c:473
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ffaa8579ef9
RSP: 002b:00007ffaa9315038 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 00007ffaa8716058 RCX: 00007ffaa8579ef9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000007
RBP: 00007ffaa85e793e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ffaa8716058 R15: 00007ffd2622fd48
 </TASK>
rcu: rcu_preempt kthread starved for 10543 jiffies! g96961 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:28128 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0xe37/0x5490 kernel/sched/core.c:6529
 __schedule_loop kernel/sched/core.c:6606 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6621
 schedule_timeout+0x136/0x2a0 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2034
 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2236
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </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:48 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:111