Free memory is -3436kB above reserved
lowmemorykiller: Killing 'syz-executor763' (11573) (tgid 11573), adj 0,
   to free 10784kB on behalf of 'kswapd0' (33) because
   cache 2356kB is below limit 6144kB for oom_score_adj 0
   Free memory is 5712kB above reserved
INFO: rcu_preempt detected stalls on CPUs/tasks:
	Tasks blocked on level-0 rcu_node (CPUs 0-1): P2102
	(detected by 0, t=10502 jiffies, g=1041, c=1040, q=126322)
syz-executor763 R  running task    26488  2102   2096 0x00000000
 0000011d82a59e80 ffffffff841ca2c0 1ffff100398f4e43 0000000100000005
 0000000041b58ab3 ffffffff82e60a80 ffffffff81d6f5c0 ffffffff81b6e700
 ffffffff00000020 ffff880100000020 ffff8801cc7a72d8 ffff8801cc7a7280
Call Trace:
==================================================================
BUG: KASAN: stack-out-of-bounds in get_frame_pointer arch/x86/include/asm/stacktrace.h:64 [inline]
BUG: KASAN: stack-out-of-bounds in __unwind_start+0x368/0x3b0 arch/x86/kernel/unwind_frame.c:76
Read of size 8 at addr ffff8801cc7a7220 by task syz-executor763/11599

CPU: 0 PID: 11599 Comm: syz-executor763 Not tainted 4.9.141+ #1
 ffff8801db607a00 ffffffff81b42e79 ffffea000731e9c0 ffff8801cc7a7220
 0000000000000000 ffff8801cc7a7220 ffff8801cd2ddf00 ffff8801db607a38
 ffffffff815009b8 ffff8801cc7a7220 0000000000000008 0000000000000000
Call Trace:
 <IRQ> 
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff815009b8>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81500dc2>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81500dc2>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff814f3074>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff810acd08>] get_frame_pointer arch/x86/include/asm/stacktrace.h:64 [inline]
 [<ffffffff810acd08>] __unwind_start+0x368/0x3b0 arch/x86/kernel/unwind_frame.c:76
 [<ffffffff810cab91>] unwind_start arch/x86/include/asm/unwind.h:39 [inline]
 [<ffffffff810cab91>] show_trace_log_lvl+0x92/0x1c8 arch/x86/kernel/dumpstack.c:70
 [<ffffffff810ca923>] show_stack_log_lvl.cold.1+0x22/0xbe arch/x86/kernel/dumpstack_64.c:188
 [<ffffffff8105a72d>] show_stack+0x4d/0x50 arch/x86/kernel/dumpstack.c:168
 [<ffffffff813fa6fd>] sched_show_task.cold.35+0x279/0x31f kernel/sched/core.c:5317
 [<ffffffff81404e39>] rcu_print_detail_task_stall_rnp+0xc2/0xfe kernel/rcu/tree_plugin.h:530
 [<ffffffff81405f5f>] rcu_print_detail_task_stall kernel/rcu/tree_plugin.h:543 [inline]
 [<ffffffff81405f5f>] print_other_cpu_stall kernel/rcu/tree.c:1408 [inline]
 [<ffffffff81405f5f>] check_cpu_stall kernel/rcu/tree.c:1520 [inline]
 [<ffffffff81405f5f>] __rcu_pending kernel/rcu/tree.c:3487 [inline]
 [<ffffffff81405f5f>] rcu_pending kernel/rcu/tree.c:3551 [inline]
 [<ffffffff81405f5f>] rcu_check_callbacks.cold.69+0x757/0xd27 kernel/rcu/tree.c:2880
 [<ffffffff81267470>] update_process_times+0x30/0x70 kernel/time/timer.c:1629
 [<ffffffff8129641a>] tick_sched_handle.isra.5+0x4a/0xf0 kernel/time/tick-sched.c:151
 [<ffffffff81296536>] tick_sched_timer+0x76/0x130 kernel/time/tick-sched.c:1190
 [<ffffffff8126a197>] __run_hrtimer kernel/time/hrtimer.c:1255 [inline]
 [<ffffffff8126a197>] __hrtimer_run_queues+0x357/0xe30 kernel/time/hrtimer.c:1319
 [<ffffffff8126c681>] hrtimer_interrupt+0x1b1/0x430 kernel/time/hrtimer.c:1353
 [<ffffffff810912d4>] local_apic_timer_interrupt+0x74/0xa0 arch/x86/kernel/apic/apic.c:937
 [<ffffffff8281b76c>] smp_apic_timer_interrupt+0x7c/0xb0 arch/x86/kernel/apic/apic.c:961
 [<ffffffff8281902d>] apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> 
 [<ffffffff81243f27>] rcu_read_lock_held+0x87/0xc0 kernel/rcu/update.c:293
 [<ffffffff8140eadc>] radix_tree_deref_slot include/linux/radix-tree.h:199 [inline]
 [<ffffffff8140eadc>] filemap_map_pages+0x6ac/0xc30 mm/filemap.c:2253
 [<ffffffff814a3cf5>] do_fault_around mm/memory.c:3135 [inline]
 [<ffffffff814a3cf5>] do_read_fault mm/memory.c:3175 [inline]
 [<ffffffff814a3cf5>] do_fault mm/memory.c:3315 [inline]
 [<ffffffff814a3cf5>] handle_pte_fault mm/memory.c:3516 [inline]
 [<ffffffff814a3cf5>] __handle_mm_fault mm/memory.c:3603 [inline]
 [<ffffffff814a3cf5>] handle_mm_fault+0x1985/0x2350 mm/memory.c:3640
 [<ffffffff81490406>] faultin_page mm/gup.c:386 [inline]
 [<ffffffff81490406>] __get_user_pages+0x446/0xf80 mm/gup.c:588
 [<ffffffff81491d6a>] populate_vma_page_range+0x19a/0x230 mm/gup.c:1106
 [<ffffffff81491fd7>] __mm_populate+0x1d7/0x320 mm/gup.c:1154
 [<ffffffff81469f25>] mm_populate include/linux/mm.h:2041 [inline]
 [<ffffffff81469f25>] vm_mmap_pgoff+0x195/0x1b0 mm/util.c:333
 [<ffffffff814af5c2>] SYSC_mmap_pgoff mm/mmap.c:1555 [inline]
 [<ffffffff814af5c2>] SyS_mmap_pgoff+0x152/0x1b0 mm/mmap.c:1513
 [<ffffffff8105d3e6>] SYSC_mmap arch/x86/kernel/sys_x86_64.c:96 [inline]
 [<ffffffff8105d3e6>] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:87
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea000731e9c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cc7a7100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cc7a7180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801cc7a7200: 00 00 00 f1 f1 f1 f1 04 f2 f2 f2 f2 f2 f2 f2 00
                               ^
 ffff8801cc7a7280: 00 00 00 00 04 f2 f2 00 00 00 00 00 00 00 00 00
 ffff8801cc7a7300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================