=============================
WARNING: suspicious RCU usage
4.14.154+ #0 Not tainted
-----------------------------
include/linux/radix-tree.h:238 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor.5/27348:
 #0:  (&sb->s_type->i_mutex_key#10){+.+.}, at: [<00000000718c8d20>] inode_lock include/linux/fs.h:724 [inline]
 #0:  (&sb->s_type->i_mutex_key#10){+.+.}, at: [<00000000718c8d20>] shmem_add_seals+0x12b/0xf80 mm/shmem.c:2831
 #1:  (&(&mapping->tree_lock)->rlock){-.-.}, at: [<00000000853139c4>] spin_lock_irq include/linux/spinlock.h:342 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){-.-.}, at: [<00000000853139c4>] shmem_tag_pins mm/shmem.c:2685 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){-.-.}, at: [<00000000853139c4>] shmem_wait_for_pins mm/shmem.c:2726 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){-.-.}, at: [<00000000853139c4>] shmem_add_seals+0x2e1/0xf80 mm/shmem.c:2843

stack backtrace:
CPU: 1 PID: 27348 Comm: syz-executor.5 Not tainted 4.14.154+ #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xe5/0x154 lib/dump_stack.c:58
 radix_tree_deref_slot include/linux/radix-tree.h:238 [inline]
 shmem_tag_pins mm/shmem.c:2687 [inline]
 shmem_wait_for_pins mm/shmem.c:2726 [inline]
 shmem_add_seals+0x9d2/0xf80 mm/shmem.c:2843
 shmem_fcntl+0xea/0x120 mm/shmem.c:2878
 do_fcntl+0x5c8/0xd20 fs/fcntl.c:421
 SYSC_fcntl fs/fcntl.c:463 [inline]
 SyS_fcntl+0xc6/0x100 fs/fcntl.c:448
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a639
RSP: 002b:00007efdb8b28c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000048
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a639
RDX: 0000000000000008 RSI: 0000000000000409 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007efdb8b296d4
R13: 00000000004c1068 R14: 00000000004d3c60 R15: 00000000ffffffff