Comment 1 for bug 742084

I have hit the same bug with the latest ubuntu kernel 2.6.38.8.

Switching on debuglebel in autofs gives the following information in the syslog file:

Apr 15 15:30:35 ebi automount[945]: umount_multi: path /net/ds-1 incl 1
Apr 15 15:30:35 ebi automount[945]: umount_multi_triggers: umount offset /net/ds-1/QAdev
Apr 15 15:30:35 ebi automount[945]: umounted offset mount /net/ds-1/QAdev
Apr 15 15:30:35 ebi automount[945]: umount_multi_triggers: umount offset /net/ds-1/QAmaint
Apr 15 15:30:35 ebi automount[945]: umounted offset mount /net/ds-1/QAmaint
Apr 15 15:30:35 ebi automount[945]: umount_multi_triggers: umount offset /net/ds-1/QAsource
Apr 15 15:30:35 ebi automount[945]: umounted offset mount /net/ds-1/QAsource
Apr 15 15:30:35 ebi automount[945]: umount_multi_triggers: umount offset /net/ds-1/doc
Apr 15 15:30:35 ebi kernel: [ 8091.088951] BUG: Dentry ffff8800c19cac00{i=5fee,n=/} still in use (3) [unmount of autofs autofs]
Apr 15 15:30:35 ebi kernel: [ 8091.088967] ------------[ cut here ]------------
Apr 15 15:30:35 ebi kernel: [ 8091.091735] kernel BUG at /build/buildd/linux-2.6.38/fs/dcache.c:947!
Apr 15 15:30:35 ebi kernel: [ 8091.093200] invalid opcode: 0000 [#1] SMP
Apr 15 15:30:35 ebi kernel: [ 8091.094687] last sysfs file: /sys/devices/virtual/bdi/0:43/uevent
Apr 15 15:30:35 ebi kernel: [ 8091.096199] CPU 2
Apr 15 15:30:35 ebi kernel: [ 8091.096212] Modules linked in: microcode parport_pc ppdev nfsd exportfs nfs lockd fscache nfs_acl auth_rpcgss autofs4 sunrpc snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi i915 snd_rawmidi snd_seq_midi_event snd_seq joydev drm_kms_helper snd_timer snd_seq_device shpchp xhci_hcd snd psmouse serio_raw soundcore snd_page_alloc drm i2c_algo_bit video lp parport hid_cherry usbhid hid e1000e ahci libahci
Apr 15 15:30:35 ebi kernel: [ 8091.102795]
Apr 15 15:30:35 ebi kernel: [ 8091.104468] Pid: 14266, comm: automount Not tainted 2.6.38-8-generic #42-Ubuntu /DH67BL
Apr 15 15:30:35 ebi kernel: [ 8091.106216] RIP: 0010:[<ffffffff81179945>] [<ffffffff81179945>] shrink_dcache_for_umount_subtree+0x285/0x290
Apr 15 15:30:35 ebi kernel: [ 8091.108002] RSP: 0018:ffff88010dbcfde8 EFLAGS: 00010296
Apr 15 15:30:35 ebi kernel: [ 8091.109785] RAX: 000000000000006a RBX: ffff8800c19cac5c RCX: 000000000000009f
Apr 15 15:30:35 ebi kernel: [ 8091.111606] RDX: 0000000000000000 RSI: 0000000000000086 RDI: 0000000000000246
Apr 15 15:30:35 ebi kernel: [ 8091.113432] RBP: ffff88010dbcfe28 R08: 0000000000000033 R09: 000000000000ce7f
Apr 15 15:30:35 ebi kernel: [ 8091.115273] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8800c19cac5c
Apr 15 15:30:35 ebi kernel: [ 8091.117131] R13: ffff8800c19cac00 R14: ffff8800c19caca0 R15: 00007f8db90b09b0
Apr 15 15:30:35 ebi kernel: [ 8091.119004] FS: 00007f8db8864700(0000) GS:ffff88001fd00000(0000) knlGS:0000000000000000
Apr 15 15:30:35 ebi kernel: [ 8091.120907] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Apr 15 15:30:35 ebi kernel: [ 8091.122833] CR2: 00007f8db88a77a0 CR3: 00000001029ba000 CR4: 00000000000406e0
Apr 15 15:30:35 ebi kernel: [ 8091.124790] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Apr 15 15:30:35 ebi kernel: [ 8091.126772] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Apr 15 15:30:35 ebi kernel: [ 8091.128768] Process automount (pid: 14266, threadinfo ffff88010dbce000, task ffff8800d92716e0)
Apr 15 15:30:35 ebi kernel: [ 8091.130803] Stack:
Apr 15 15:30:35 ebi kernel: [ 8091.132841] ffff8800d8ea4a58 ffffffff81177156 0000000000000000 ffff8800d8ea4800
Apr 15 15:30:35 ebi kernel: [ 8091.134943] ffff8800c19cac5c ffff8800c19cac00 00007f8db90b2500 00007f8db90b09b0
Apr 15 15:30:35 ebi kernel: [ 8091.137042] ffff88010dbcfe58 ffffffff8117c2a1 ffff88010dbcfe48 ffff8800d8ea4800
Apr 15 15:30:35 ebi kernel: [ 8091.139149] Call Trace:
Apr 15 15:30:35 ebi kernel: [ 8091.141233] [<ffffffff81177156>] ? pollwake+0x56/0x60
Apr 15 15:30:35 ebi kernel: [ 8091.143321] [<ffffffff8117c2a1>] shrink_dcache_for_umount+0x51/0x90
Apr 15 15:30:35 ebi kernel: [ 8091.145399] [<ffffffff81166bfc>] generic_shutdown_super+0x2c/0x100
Apr 15 15:30:35 ebi kernel: [ 8091.147471] [<ffffffff81166d66>] kill_anon_super+0x16/0x60
Apr 15 15:30:35 ebi kernel: [ 8091.149525] [<ffffffff81166dd7>] kill_litter_super+0x27/0x30
Apr 15 15:30:35 ebi kernel: [ 8091.151568] [<ffffffffa02ed4d8>] autofs4_kill_sb+0x48/0x60 [autofs4]
Apr 15 15:30:35 ebi kernel: [ 8091.153602] [<ffffffff811671d5>] deactivate_locked_super+0x45/0x70
Apr 15 15:30:35 ebi kernel: [ 8091.155620] [<ffffffff81167e5a>] deactivate_super+0x4a/0x70
Apr 15 15:30:35 ebi kernel: [ 8091.157625] [<ffffffff81183254>] mntput_no_expire+0xa4/0xf0
Apr 15 15:30:35 ebi kernel: [ 8091.159612] [<ffffffff811842e0>] sys_umount+0x60/0xd0
Apr 15 15:30:35 ebi kernel: [ 8091.161621] [<ffffffff8100c002>] system_call_fastpath+0x16/0x1b
Apr 15 15:30:35 ebi kernel: [ 8091.163623] Code: 8b 40 28 4c 8b 08 49 8b 45 30 48 85 c0 74 07 48 8b 90 a8 00 00 00 48 89 34 24 48 c7 c7 50 6c 7e 81 4c 89 ee 31 c0 e8 94 66 44 00 <0f> 0b 0f 0b 0f 1f 80 00 00 00 00 55 48 89 e5 48 83 ec 20 48 89
Apr 15 15:30:35 ebi kernel: [ 8091.168029] RIP [<ffffffff81179945>] shrink_dcache_for_umount_subtree+0x285/0x290
Apr 15 15:30:35 ebi kernel: [ 8091.170206] RSP <ffff88010dbcfde8>
Apr 15 15:30:35 ebi kernel: [ 8091.237306] ---[ end trace 716bb764db911714 ]---