rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P13494/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=331265, q=515 ncpus=2)
task:syz-executor.5  state:R  running task     stack:26768 pid:13494 tgid:13494 ppid:23160  flags:0x00000002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5376 [inline]
 __schedule+0xee2/0x59a0 kernel/sched/core.c:6688
 preempt_schedule_irq+0x52/0x90 kernel/sched/core.c:7008
 irqentry_exit+0x35/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
RIP: 0010:lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5721
Code: c1 05 dd 7d 99 7e 83 f8 01 0f 85 b0 02 00 00 9c 58 f6 c4 02 0f 85 9b 02 00 00 48 85 ed 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 8b 84 24
RSP: 0018:ffffc90005de77a0 EFLAGS: 00000206
RAX: dffffc0000000000 RBX: 1ffff92000bbcef6 RCX: 0000000000000001
RDX: 1ffff11007bbbc7f RSI: ffffffff8accbc20 RDI: ffffffff8b2eee80
RBP: 0000000000000200 R08: 0000000000000000 R09: fffffbfff23e3fd0
R10: ffffffff91f1fe87 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff8cfacfe0 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
 rcu_read_lock include/linux/rcupdate.h:747 [inline]
 page_ext_get+0x3a/0x310 mm/page_ext.c:508
 __page_table_check_zero+0x139/0x5e0 mm/page_table_check.c:140
 page_table_check_free include/linux/page_table_check.h:41 [inline]
 free_pages_prepare mm/page_alloc.c:1138 [inline]
 free_unref_page_prepare+0x4e8/0xa90 mm/page_alloc.c:2347
 free_unref_page+0x33/0x3b0 mm/page_alloc.c:2487
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x18e/0x1d0 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x65/0x90 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook mm/slab.h:763 [inline]
 slab_alloc_node mm/slub.c:3478 [inline]
 slab_alloc mm/slub.c:3486 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3493 [inline]
 kmem_cache_alloc+0x15d/0x380 mm/slub.c:3502
 vma_lock_alloc kernel/fork.c:459 [inline]
 vm_area_dup+0x53/0x2f0 kernel/fork.c:512
 __split_vma+0x17d/0x1070 mm/mmap.c:2365
 split_vma mm/mmap.c:2437 [inline]
 vma_modify+0x25d/0x450 mm/mmap.c:2472
 vma_modify_flags include/linux/mm.h:3271 [inline]
 mprotect_fixup+0x228/0xc80 mm/mprotect.c:635
 do_mprotect_pkey+0x852/0xd60 mm/mprotect.c:809
 __do_sys_mprotect mm/mprotect.c:830 [inline]
 __se_sys_mprotect mm/mprotect.c:827 [inline]
 __x64_sys_mprotect+0x78/0xb0 mm/mprotect.c:827
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f224007cba7
RSP: 002b:00007f22402bf9e8 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 00007f2240e2f6c0 RCX: 00007f224007cba7
RDX: 0000000000000003 RSI: 0000000000020000 RDI: 00007f2240e10000
RBP: 0000000000000000 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000021000 R11: 0000000000000206 R12: 00007f22402bfc90
R13: ffffffffffffffc0 R14: 0000000000001000 R15: 0000000000000000
 </TASK>