===============================
[ 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-executor234/2038:
 #0:  (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<000000003e6b3d62>] inode_lock include/linux/fs.h:771 [inline]
 #0:  (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<000000003e6b3d62>] shmem_add_seals+0x166/0x1020 mm/shmem.c:2610
 #1:  (&(&mapping->tree_lock)->rlock){..-...}, at: [<00000000b68af91c>] spin_lock_irq include/linux/spinlock.h:332 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){..-...}, at: [<00000000b68af91c>] shmem_tag_pins mm/shmem.c:2465 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){..-...}, at: [<00000000b68af91c>] shmem_wait_for_pins mm/shmem.c:2506 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){..-...}, at: [<00000000b68af91c>] shmem_add_seals+0x342/0x1020 mm/shmem.c:2622

stack backtrace:
CPU: 1 PID: 2038 Comm: syz-executor234 Not tainted 4.9.202+ #0
 ffff8801cf06fca0 ffffffff81b55d2b ffff8801cf0c42c8 0000000000000000
 0000000000000002 00000000000000c7 ffff8801d1d9c740 ffff8801cf06fcd0
 ffffffff81406867 ffffea000748b3c0 dffffc0000000000 ffff8801cf06fd78
Call Trace:
 [<00000000f81e9fb9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000f81e9fb9>] dump_stack+0xcb/0x130 lib/dump_stack.c:56
 [<00000000f827df8c>] lockdep_rcu_suspicious.cold+0x10a/0x149 kernel/locking/lockdep.c:4458
 [<0000000093ce2d28>] radix_tree_deref_slot include/linux/radix-tree.h:199 [inline]
 [<0000000093ce2d28>] shmem_tag_pins mm/shmem.c:2467 [inline]
 [<0000000093ce2d28>] shmem_wait_for_pins mm/shmem.c:2506 [inline]
 [<0000000093ce2d28>] shmem_add_seals+0xa44/0x1020 mm/shmem.c:2622
 [<00000000ac2fef53>] shmem_fcntl+0xf7/0x130 mm/shmem.c:2657
 [<00000000cc3389a1>] SyS_fcntl+0