cramfs: empty filesystem
ptrace attach of "/root/syz-executor.4"[30623] was attempted by "/root/syz-executor.4"[30627]
INFO: task syz-executor.1:30643 blocked for more than 140 seconds.
      Not tainted 4.14.225-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D29184 30643   8010 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:588 [inline]
 rwsem_down_write_failed+0x343/0x6d0 kernel/locking/rwsem-xadd.c:617
 call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:105
 __down_write arch/x86/include/asm/rwsem.h:126 [inline]
 down_write+0x4f/0x90 kernel/locking/rwsem.c:56
 grab_super+0x55/0x140 fs/super.c:373
 sget_userns+0x2b1/0xc10 fs/super.c:504
 sget+0xd1/0x110 fs/super.c:572
 mount_bdev+0xcd/0x360 fs/super.c:1107
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0xe53/0x2a00 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3072
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x465f69
RSP: 002b:00007f6a26aa9188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 000000000056c0b0 RCX: 0000000000465f69
RDX: 0000000020000500 RSI: 00000000200004c0 RDI: 0000000020000180
RBP: 00000000004bfa8f R08: 0000000020000540 R09: 0000000000000000
R10: 0000000004000000 R11: 0000000000000246 R12: 000000000056c0b0
R13: 00007fff556ad56f R14: 00007f6a26aa9300 R15: 0000000000022000

Showing all locks held in the system:
1 lock held by khungtaskd/1525:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff86ff2967>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
2 locks held by syz-executor.1/30643:
 #0:  (&bdev->bd_fsfreeze_mutex){+.+.}, at: [<ffffffff81871de1>] mount_bdev+0x71/0x360 fs/super.c:1101
 #1:  (&type->s_umount_key#76){+.+.}, at: [<ffffffff81870e75>] grab_super+0x55/0x140 fs/super.c:373

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1525 Comm: khungtaskd Not tainted 4.14.225-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x180 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5b9/0xb40 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 30570 Comm: syz-executor.1 Not tainted 4.14.225-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888054620600 task.stack: ffff8880581f8000
RIP: 0010:find_held_lock+0x7/0x210 kernel/locking/lockdep.c:3596
RSP: 0018:ffff8880581ffa20 EFLAGS: 00000002
RAX: 0000000000000002 RBX: 1ffff1100b03ff4a RCX: ffff8880581ffa70
RDX: 0000000000000002 RSI: ffffffff88f777c0 RDI: ffff888054620600
RBP: ffffffff88f777c0 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffff888054620600 R12: ffffffff81682032
R13: ffffffff8beb5d40 R14: ffff888054620600 R15: ffffffff88f777c0
FS:  00007f6a26aca700(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f673ad70000 CR3: 000000009bead000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __lock_release kernel/locking/lockdep.c:3767 [inline]
 lock_release+0x237/0x870 kernel/locking/lockdep.c:4017
 rcu_lock_release include/linux/rcupdate.h:247 [inline]
 rcu_read_unlock include/linux/rcupdate.h:685 [inline]
 find_get_entry+0x339/0x630 mm/filemap.c:1392
 pagecache_get_page+0x53/0xab0 mm/filemap.c:1465
 find_or_create_page include/linux/pagemap.h:326 [inline]
 grow_dev_page fs/buffer.c:1004 [inline]
 grow_buffers fs/buffer.c:1077 [inline]
 __getblk_slow+0x1dd/0x7a0 fs/buffer.c:1104
 __getblk_gfp fs/buffer.c:1383 [inline]
 __bread_gfp+0x206/0x2e0 fs/buffer.c:1428
 sb_bread include/linux/buffer_head.h:309 [inline]
 sysv_fill_super+0x192/0x710 fs/sysv/super.c:378
 mount_bdev+0x2b3/0x360 fs/super.c:1134
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0xe53/0x2a00 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3072
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x465f69
RSP: 002b:00007f6a26aca188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465f69
RDX: 0000000020000500 RSI: 00000000200004c0 RDI: 0000000020000180
RBP: 00000000004bfa8f R08: 0000000020000540 R09: 0000000000000000
R10: 0000000004000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007fff556ad56f R14: 00007f6a26aca300 R15: 0000000000022000
Code: fd ff ff 48 c7 c7 c8 92 f0 88 e8 f5 80 3d 00 e9 36 ff ff ff e9 6c fc bd 05 66 66 2e 0f 1f 84 00 00 00 00 00 41 57 49 89 f7 41 56 <49> 89 ce 41 55 44 8d 6a ff 49 63 c5 41 54 48 8d 04 80 55 4c 8d