============================= 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.3/3870: #0: (&sb->s_type->i_mutex_key#10){+.+.}, at: [<000000001e3f38c2>] inode_lock include/linux/fs.h:724 [inline] #0: (&sb->s_type->i_mutex_key#10){+.+.}, at: [<000000001e3f38c2>] shmem_add_seals+0x12b/0xf80 mm/shmem.c:2831 #1: (&(&mapping->tree_lock)->rlock){-.-.}, at: [<000000000eee79e5>] spin_lock_irq include/linux/spinlock.h:342 [inline] #1: (&(&mapping->tree_lock)->rlock){-.-.}, at: [<000000000eee79e5>] shmem_tag_pins mm/shmem.c:2685 [inline] #1: (&(&mapping->tree_lock)->rlock){-.-.}, at: [<000000000eee79e5>] shmem_wait_for_pins mm/shmem.c:2726 [inline] #1: (&(&mapping->tree_lock)->rlock){-.-.}, at: [<000000000eee79e5>] shmem_add_seals+0x2e1/0xf80 mm/shmem.c:2843 stack backtrace: CPU: 1 PID: 3870 Comm: syz-executor.3 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 FAT-fs (loop1): bogus number of FAT structure do_fcntl+0x5c8/0xd20 fs/fcntl.c:421 SYSC_fcntl fs/fcntl.c:463 [inline] SyS_fcntl+0xc6/0x100 fs/fcntl.c:448 FAT-fs (loop1): Can't find a valid FAT filesystem do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45a639 RSP: 002b:00007fed99ee6c78 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: 00007fed99ee76d4 R13: 00000000004c1068 R14: 00000000004d3c60 R15: 00000000ffffffff IPv6: addrconf: prefix option has invalid lifetime IPv6: addrconf: prefix option has invalid lifetime EXT4-fs (loop1): mounting ext2 file system using the ext4 subsystem EXT4-fs (loop1): ext4_check_descriptors: Block bitmap for group 0 overlaps block group descriptors EXT4-fs (loop1): ext4_check_descriptors: Inode bitmap for group 0 overlaps superblock EXT4-fs (loop1): ext4_check_descriptors: Inode table for group 0 overlaps superblock EXT4-fs (loop1): mounted filesystem without journal. Opts: ,errors=continue audit: type=1400 audit(1574109937.152:23): avc: denied { map } for pid=4246 comm="syz-executor.4" path="/root/syzkaller-testdir790284610/syzkaller.5qGVi3/20/file0/bus" dev="ramfs" ino=10806 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:ramfs_t:s0 tclass=file permissive=1 syz-executor.2 (4294) used greatest stack depth: 23472 bytes left EXT4-fs (loop5): bad geometry: block count 12884902968 exceeds size of device (66048 blocks) TCP: request_sock_TCPv6: Possible SYN flooding on port 20000. Dropping request. Check SNMP counters. UHID_CREATE from different security context by process 97 (syz-executor.3), this is not allowed.