===============================
[ INFO: suspicious RCU usage. ]
4.9.202+ #0 Not tainted
-------------------------------
include/linux/radix-tree.h:199 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
2 locks held by syz-executor190/2044:
 #0:  (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<0000000060a1d721>] inode_lock include/linux/fs.h:771 [inline]
 #0:  (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<0000000060a1d721>] shmem_add_seals+0x166/0x1020 mm/shmem.c:2610
 #1:  (&(&mapping->tree_lock)->rlock){..-...}, at: [<00000000d0941056>] spin_lock_irq include/linux/spinlock.h:332 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){..-...}, at: [<00000000d0941056>] shmem_tag_pins mm/shmem.c:2465 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){..-...}, at: [<00000000d0941056>] shmem_wait_for_pins mm/shmem.c:2506 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){..-...}, at: [<00000000d0941056>] shmem_add_seals+0x342/0x1020 mm/shmem.c:2622

stack backtrace:
CPU: 1 PID: 2044 Comm: syz-executor190 Not tainted 4.9.202+ #0
 ffff8801d13cfca0 ffffffff81b55d2b ffff8801c4c50de8 0000000000000000
 0000000000000002 00000000000000c7 ffff8801d144c740 ffff8801d13cfcd0
 ffffffff81406867 ffffea000735f240 dffffc0000000000 ffff8801d13cfd78
Call Trace:
 [<000000006dc5ea78>] __dump_stack lib/dump_stack.c:15 [inline]
 [<000000006dc5ea78>] dump_stack+0xcb/0x130 lib/dump_stack.c:56
 [<00000000e4809cf9>] lockdep_rcu_suspicious.cold+0x10a/0x149 kernel/locking/lockdep.c:4458
 [<000000002ad946d1>] radix_tree_deref_slot include/linux/radix-tree.h:199 [inline]
 [<000000002ad946d1>] shmem_tag_pins mm/shmem.c:2467 [inline]
 [<000000002ad946d1>] shmem_wait_for_pins mm/shmem.c:2506 [inline]
 [<000000002ad946d1>] shmem_add_seals+0xa44/0x1020 mm/shmem.c:2622
 [<000000009cfe3662>] shmem_fcntl+0xf7/0x130 mm/shmem.c:2657
 [<00000000977e0214>] do_fcntl fs/fcntl.c:340 [inline]
 [<00000000977e0214>] SYSC_fcntl fs/fcntl.c:376 [inline]
 [<00000000977e0214>] SyS_fcntl+0x1d5/0xb50 fs/fcntl.c:361
 [<000000002ba05cd8>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 [<00000000d78fddb7>] entry_SYSCALL_64_af