when I mount (via fstab) a specific folder
10.10.140.210:6789:/pool-hs-san-1     /mnt/ceph1-pool-hs-san-1    ceph    name=admin,noauto,rw,noexec,nodev,noatime,nodiratime    0       2

the mount is successful.

when I mount (via fstab)
10.10.140.210:6789:/     /mnt/ceph1-kernel    ceph    name=admin,noauto,rw,noexec,nodev,noatime,nodiratime    0       2

I get the following to dmesg:

[112151.148435] libceph: loaded (mon/osd proto 15/24, osdmap 5/6 5/6)
[112151.170881] ceph: loaded (mds proto 32)
[112151.173070] libceph: client0 fsid 7e9dfb5f-4af9-4f65-a2fe-47cc19766243
[112151.173902] libceph: mon0 10.10.140.210:6789 session established
[112186.650920] BUG: unable to handle kernel NULL pointer dereference at           (null)
[112186.651826] IP: [<ffffffffa02590d2>] ceph_d_prune+0x22/0x30 [ceph]
[112186.652536] PGD 4010067 PUD 5237067 PMD 0
[112186.653010] Oops: 0002 [#1] SMP
[112186.653010] CPU 1
[112186.653010] Modules linked in: ceph libceph libcrc32c dcdbas bonding serio_raw xgifb(C) shpchp i3000_edac edac_core mac_hid lp parport xfs raid10 raid456 async_pq async_xor xor async_memcpy async_raid6_recov e1000 tg3 raid6_pq async_tx raid1 raid0 multipath linear
[112186.653010]
[112186.653010] Pid: 11104, comm: umount Tainted: G         C   3.2.0-23-generic #36-Ubuntu Dell Computer Corporation PowerEdge 850/0FJ365
[112186.653010] RIP: 0010:[<ffffffffa02590d2>]  [<ffffffffa02590d2>] ceph_d_prune+0x22/0x30 [ceph]
[112186.653010] RSP: 0018:ffff880036e69e08  EFLAGS: 00010282
[112186.653010] RAX: 0000000000000000 RBX: ffff8800058bcc00 RCX: 0000000180150010
[112186.653010] RDX: ffff8800058bcca0 RSI: ffffea00012c1100 RDI: ffff8800058bcc00
[112186.653010] RBP: ffff880036e69e08 R08: 0000000000000001 R09: 0000000000000000
[112186.653010] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8800058bcc80
[112186.653010] R13: 0000000001f113c0 R14: 0000000000000000 R15: 0000000000000000
[112186.653010] FS:  00007fb1b7979800(0000) GS:ffff88010fd00000(0000) knlGS:0000000000000000
[112186.653010] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[112186.653010] CR2: 0000000000000000 CR3: 0000000003c25000 CR4: 00000000000006e0
[112186.653010] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[112186.653010] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[112186.653010] Process umount (pid: 11104, threadinfo ffff880036e68000, task ffff8800051ec4d0)
[112186.653010] Stack:
[112186.653010]  ffff880036e69e28 ffffffff8118c717 ffff8800058bcc00 ffffffffa026f0e0
[112186.653010]  ffff880036e69e58 ffffffff8118d6ea ffff880036e69e18 ffff880036e69e18
[112186.653010]  ffff880104979800 ffffffffa026f0e0 ffff880036e69e78 ffffffff8118f6a9
[112186.653010] Call Trace:
[112186.653010]  [<ffffffff8118c717>] dentry_lru_prune+0x97/0xa0
[112186.653010]  [<ffffffff8118d6ea>] shrink_dcache_for_umount_subtree+0x7a/0x1e0
[112186.653010]  [<ffffffff8118f6a9>] shrink_dcache_for_umount+0x49/0x60
[112186.735879]  [<ffffffff81179bbc>] generic_shutdown_super+0x2c/0xe0
[112186.735879]  [<ffffffff81179d06>] kill_anon_super+0x16/0x30
[112186.735879]  [<ffffffffa02550c0>] ceph_kill_sb+0x30/0x50 [ceph]
[112186.802472]  [<ffffffff8117a34c>] deactivate_locked_super+0x3c/0xa0
[112186.802472]  [<ffffffff8117abbe>] deactivate_super+0x4e/0x70
[112186.832171]  [<ffffffff811971dd>] mntput_no_expire+0x9d/0xf0
[112186.832171]  [<ffffffff811984fb>] sys_umount+0x5b/0xd0
[112186.832171]  [<ffffffff81664a82>] system_call_fastpath+0x16/0x1b
[112186.832171] Code: 66 90 b8 01 00 00 00 5d c3 55 48 89 e5 66 66 66 66 90 48 8b 47 18 48 85 c0 74 14 48 39 c7 74 0f 48 83 7f 10 00 74 08 48 8b 40 78 <f0> 80 20 fd 5d c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 48 83 ec
[112186.832171] RIP  [<ffffffffa02590d2>] ceph_d_prune+0x22/0x30 [ceph]
[112186.832171]  RSP <ffff880036e69e08>
[112186.832171] CR2: 0000000000000000
[112187.047029] ---[ end trace 4e4a2b237a888ee4 ]---