============================================
WARNING: possible recursive locking detected
5.3.0-rc6+ #0 Not tainted
--------------------------------------------
oom_reaper/1065 is trying to acquire lock:
ffffffff88645bc0 (mmu_notifier_invalidate_range_start){+.+.}, at: __mmu_notifier_invalidate_range_end+0x0/0x300 mm/mmu_notifier.c:169

but task is already holding lock:
ffffffff88645bc0 (mmu_notifier_invalidate_range_start){+.+.}, at: __oom_reap_task_mm+0x1b6/0x3d0 mm/oom_kill.c:543

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(mmu_notifier_invalidate_range_start);
  lock(mmu_notifier_invalidate_range_start);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by oom_reaper/1065:
 #0: ffff888090ff02d0 (&mm->mmap_sem#2){++++}, at: oom_reap_task_mm mm/oom_kill.c:571 [inline]
 #0: ffff888090ff02d0 (&mm->mmap_sem#2){++++}, at: oom_reap_task mm/oom_kill.c:614 [inline]
 #0: ffff888090ff02d0 (&mm->mmap_sem#2){++++}, at: oom_reaper+0x297/0xd00 mm/oom_kill.c:652
 #1: ffffffff88645bc0 (mmu_notifier_invalidate_range_start){+.+.}, at: __oom_reap_task_mm+0x1b6/0x3d0 mm/oom_kill.c:543

stack backtrace:
CPU: 1 PID: 1065 Comm: oom_reaper Not tainted 5.3.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x113/0x167 lib/dump_stack.c:113
 print_deadlock_bug kernel/locking/lockdep.c:2371 [inline]
 check_deadlock kernel/locking/lockdep.c:2412 [inline]
 validate_chain kernel/locking/lockdep.c:2955 [inline]
 __lock_acquire.cold.66+0x15d/0x398 kernel/locking/lockdep.c:3955
 lock_acquire+0x194/0x410 kernel/locking/lockdep.c:4487
 __mmu_notifier_invalidate_range_end+0x37/0x300 mm/mmu_notifier.c:193
 mmu_notifier_invalidate_range_end include/linux/mmu_notifier.h:375 [inline]
 __oom_reap_task_mm+0x2b4/0x3d0 mm/oom_kill.c:553
 oom_reap_task_mm mm/oom_kill.c:590 [inline]
 oom_reap_task mm/oom_kill.c:614 [inline]
 oom_reaper+0x20f/0xd00 mm/oom_kill.c:652
 kthread+0x331/0x3f0 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
oom_reaper: reaped process 7867 (syz-executor.1), now anon-rss:18232kB, file-rss:19516kB, shmem-rss:0kB
oom_reaper: reaped process 7891 (syz-executor.5), now anon-rss:18232kB, file-rss:19516kB, shmem-rss:0kB
oom_reaper: reaped process 7894 (syz-executor.2), now anon-rss:18232kB, file-rss:19516kB, shmem-rss:0kB
oom_reaper: reaped process 7898 (syz-executor.4), now anon-rss:18352kB, file-rss:19516kB, shmem-rss:0kB
oom_reaper: reaped process 7906 (syz-executor.3), now anon-rss:18200kB, file-rss:18552kB, shmem-rss:0kB
oom_reaper: reaped process 7856 (syz-executor.1), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 7850 (syz-executor.5), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 7887 (syz-executor.2), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 7802 (syz-executor.2), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 7943 (syz-executor.1), now anon-rss:17868kB, file-rss:19516kB, shmem-rss:0kB
oom_reaper: reaped process 7947 (syz-executor.5), now anon-rss:18324kB, file-rss:18552kB, shmem-rss:0kB
oom_reaper: reaped process 7959 (syz-executor.0), now anon-rss:18172kB, file-rss:19512kB, shmem-rss:0kB
oom_reaper: reaped process 7764 (syz-executor.0), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 7834 (syz-executor.4), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 7969 (syz-executor.3), now anon-rss:18208kB, file-rss:18552kB, shmem-rss:0kB