Program hangs when mountpoint and items directory are the same
Opened this issue · 3 comments
MarSoft commented
I made a directory /tmp/x with subdirectories /tmp/x/a and /tmp/x/b, which in turn contained simple index files. Then I issued a following command:
$ tagfs /tmp/x -i /tmp/x
And it hung. I couldn't terminate it even with killall -9 tagfs. Then I tried to rmmod -f fuse, and it worked. But few minutes later system hung completely.
I didn't investigate problem deeper yet.
pitrp commented
Wow! Just wow! I'd expected some part of the chain to bail out.
What would be the correct behaviour?
Did you intend to shadow /tmp/x/*?
Shadowing is probably out of scope for tagfs. Unionfs or similar could be used if desired. But we certainly have to handle this problem. Grave Bug.
marook commented
I can't reproduce the problem using MarSoft's command directly:
$ tagfs /tmp/x -i /tmp/x
fuse: mountpoint is not empty
fuse: if you are sure this is safe, use the 'nonempty' mount option
Traceback (most recent call last):
File "/home/marook/.local/bin/tagfs", line 41, in
sys.exit(main())
File "/home/marook/.local/lib/python/tagfs/tagfs.py", line 169, in main
return fs.main()
File "/usr/lib/python2.6/dist-packages/fuse.py", line 757, in main
main(**d)
fuse.FuseError: filesystem initialization failed
But when I slightly modify the call I can reproduce the problem:
$ tagfs -o nonempty /tmp/x -i /tmp/x
After the tagfs call returns everything seems normal at first. When I do a
$ ls /tmp
the call never returns.
So I do a
$ rmmod fuse
which can't remove the fuse module because it's still in use.
When I call
$ rmmod -f fuse
the fuse module is unloaded. But this seems to break my system. dmesg says me:
[15922.723773] Disabling lock debugging due to kernel taint
[15922.725710] fuse exit
[15922.725742] =============================================================================
[15922.727754] BUG fuse_inode: Objects remaining on kmem_cache_close()
[15922.729705] -----------------------------------------------------------------------------
[15922.729705]
[15922.729705] INFO: Slab 0xc1b510c0 objects=18 used=1 fp=0xf3f87dc0 flags=0x40004080
[15922.729705] Pid: 9634, comm: rmmod Tainted: G R 2.6.32-5-686 #1
[15922.729705] Call Trace:
[15922.729705] [<c10ac7e4>] ? slab_err+0x65/0x7e
[15922.729705] [<c10c1c4f>] ? find_inode+0x1b/0x56
[15922.729705] [<c10130e5>] ? native_send_call_func_single_ipi+0x21/0x22
[15922.729705] [<c105285f>] ? generic_exec_single+0x4f/0x66
[15922.729705] [<c10ad359>] ? list_slab_objects+0x58/0xf6
[15922.729705] [<c10ad322>] ? list_slab_objects+0x21/0xf6
[15922.729705] [<c10acdcf>] ? deactivate_slab+0x90/0xa8
[15922.729705] [<c10af4c8>] ? kmem_cache_destroy+0xbb/0x13f
[15922.729705] [<f7e3e3cf>] ? fuse_exit+0x28/0x2e [fuse]
[15922.729705] [<c1055a8f>] ? sys_delete_module+0x19f/0x20f
[15922.729705] [<c10091a9>] ? init_fpu+0xaa/0x147
[15922.729705] [<c126f65f>] ? do_page_fault+0x2f1/0x307
[15922.729705] [<c10030fb>] ? sysenter_do_call+0x12/0x28
[15922.729705] INFO: Object 0xf3f86000 @offset=0
[15922.770408] SLUB fuse_inode: kmem_cache_destroy called for cache that still has objects.
[15922.772724] Pid: 9634, comm: rmmod Tainted: G R 2.6.32-5-686 #1
[15922.775117] Call Trace:
[15922.777481] [<c10af507>] ? kmem_cache_destroy+0xfa/0x13f
[15922.779941] [<f7e3e3cf>] ? fuse_exit+0x28/0x2e [fuse]
[15922.782443] [<c1055a8f>] ? sys_delete_module+0x19f/0x20f
[15922.784945] [<c10091a9>] ? init_fpu+0xaa/0x147
[15922.784951] [<c126f65f>] ? do_page_fault+0x2f1/0x307
[15922.784959] [<c10030fb>] ? sysenter_do_call+0x12/0x28
[15922.788247] =============================================================================
[15922.788250] BUG fuse_request: Objects remaining on kmem_cache_close()
[15922.788252] -----------------------------------------------------------------------------
[15922.788254]
[15922.788257] INFO: Slab 0xc1b0c340 objects=20 used=2 fp=0xf1d1ba90 flags=0x40004080
[15922.788262] Pid: 9634, comm: rmmod Tainted: G R 2.6.32-5-686 #1
[15922.788265] Call Trace:
[15922.788270] [<c10ac7e4>] ? slab_err+0x65/0x7e
[15922.788276] [<c10f33d3>] ? release_sysfs_dirent+0x6d/0x81
[15922.788280] [<c10130e5>] ? native_send_call_func_single_ipi+0x21/0x22
[15922.788284] [<c105285f>] ? generic_exec_single+0x4f/0x66
[15922.788288] [<c10ad359>] ? list_slab_objects+0x58/0xf6
[15922.788291] [<c10ad322>] ? list_slab_objects+0x21/0xf6
[15922.788295] [<c10acdcf>] ? deactivate_slab+0x90/0xa8
[15922.788298] [<c10af4c8>] ? kmem_cache_destroy+0xbb/0x13f
[15922.788306] [<c1055a8f>] ? sys_delete_module+0x19f/0x20f
[15922.788310] [<c10091a9>] ? init_fpu+0xaa/0x147
[15922.788314] [<c126f65f>] ? do_page_fault+0x2f1/0x307
[15922.788317] [<c10030fb>] ? sysenter_do_call+0x12/0x28
[15922.788322] INFO: Object 0xf1d1a000 @offset=0
[15922.788325] INFO: Object 0xf1d1bdb0 @offset=7600
[15922.788327] =============================================================================
[15922.788329] BUG fuse_request: Objects remaining on kmem_cache_close()
[15922.788331] -----------------------------------------------------------------------------
[15922.788332]
[15922.788335] INFO: Slab 0xc1a2d640 objects=20 used=3 fp=0xeadb3db0 flags=0x40004080
[15922.788338] Pid: 9634, comm: rmmod Tainted: G R 2.6.32-5-686 #1
[15922.788340] Call Trace:
[15922.788343] [<c10ac7e4>] ? slab_err+0x65/0x7e
[15922.788347] [<c10ad359>] ? list_slab_objects+0x58/0xf6
[15922.788350] [<c10ad322>] ? list_slab_objects+0x21/0xf6
[15922.788354] [<c10acdcf>] ? deactivate_slab+0x90/0xa8
[15922.788358] [<c10af4c8>] ? kmem_cache_destroy+0xbb/0x13f
[15922.788362] [<c1055a8f>] ? sys_delete_module+0x19f/0x20f
[15922.788366] [<c10091a9>] ? init_fpu+0xaa/0x147
[15922.788369] [<c126f65f>] ? do_page_fault+0x2f1/0x307
[15922.788373] [<c10030fb>] ? sysenter_do_call+0x12/0x28
[15922.788377] INFO: Object 0xeadb2000 @offset=0
[15922.788379] INFO: Object 0xeadb2190 @offset=400
[15922.788381] INFO: Object 0xeadb2960 @offset=2400
[15922.788384] SLUB fuse_request: kmem_cache_destroy called for cache that still has objects.
[15922.788387] Pid: 9634, comm: rmmod Tainted: G R 2.6.32-5-686 #1
[15922.788389] Call Trace:
[15922.788392] [<c10af507>] ? kmem_cache_destroy+0xfa/0x13f
[15922.788396] [<c1055a8f>] ? sys_delete_module+0x19f/0x20f
[15922.788400] [<c10091a9>] ? init_fpu+0xaa/0x147
[15922.788404] [<c126f65f>] ? do_page_fault+0x2f1/0x307
[15922.788407] [<c10030fb>] ? sysenter_do_call+0x12/0x28
[15948.725421] BUG: unable to handle kernel NULL pointer dereference at (null)
[15948.725543] IP: [<c10c65e4>] seq_escape+0x85/0xa3
[15948.725628] *pde = 00000000
[15948.725682] Oops: 0000 [#1] SMP
[15948.725746] last sysfs file: /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:00/PNP0C09:00/PNP0C0A:00/power_supply/BAT0/status
[15948.725917] Modules linked in: serpent cbc usb_storage aes_i586 aes_generic nls_utf8 isofs loop binfmt_misc parport_pc ppdev lp parport sco bridge stp bnep rfcomm l2cap crc16 nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack xt_tcpudp xt_mac iptable_filter ip_tables x_tables acpi_cpufreq cpufreq_userspace cpufreq_stats cpufreq_powersave cpufreq_conservative dm_crypt dm_mod snd_hda_codec_analog arc4 ecb snd_hda_intel iwl3945 i915 snd_hda_codec iwlcore drm_kms_helper thinkpad_acpi snd_hwdep drm mac80211 snd_pcm pcmcia snd_seq btusb led_class i2c_i801 i2c_algo_bit yenta_socket snd_timer snd_seq_device rsrc_nonstatic i2c_core pcmcia_core rng_core evdev cfg80211 bluetooth snd battery nvram button video soundcore snd_page_alloc processor pcspkr ac psmouse output rfkill serio_raw xfs exportfs sg sr_mod usbhid hid cdrom sd_mod crc_t10dif ata_generic ahci ata_piix uhci_hcd thermal libata e1000e thermal_sys ehci_hcd scsi_mod usbcore nls_base [last unloaded: fuse]
[15948.727826]
[15948.727856] Pid: 1956, comm: gnome-settings- Tainted: G R (2.6.32-5-686 #1) 1951PRG
[15948.727977] EIP: 0060:[<c10c65e4>] EFLAGS: 00210286 CPU: 0
[15948.728060] EIP is at seq_escape+0x85/0xa3
[15948.728123] EAX: 00000000 EBX: c3f33200 ECX: c12fd66b EDX: ea90f000
[15948.728212] ESI: ea90e1fa EDI: eaa3d8a0 EBP: f6f64db0 ESP: f5aaff00
[15948.728303] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[15948.728381] Process gnome-settings- (pid: 1956, ti=f5aae000 task=f5a32640 task.ti=f5aae000)
[15948.728502] Stack:
[15948.728535] c12fd66b 00000000 ea90f000 c3f33200 eaa3d8a0 eaa3d8a0 f6f64db0 c10c3c84
[15948.728690] <0> c127f934 f6f64d80 c10c4020 f6f64d80 f68cd198 c127f934 eaa3d8a0 000001d9
[15948.728859] <0> f6f64db0 c10c69ec 00000400 b6826000 f2625680 eaa3d8c8 00000000 00000008
[15948.729035] Call Trace:
[15948.729077] [<c10c3c84>] ? show_type+0x17/0x49
[15948.729090] [<c10c4020>] ? show_vfsmnt+0x5f/0xd8
[15948.729090] [<c10c69ec>] ? seq_read+0x28a/0x360
[15948.729090] [<c10c6762>] ? seq_read+0x0/0x360
[15948.729090] [<c10b36cc>] ? vfs_read+0x7b/0xd3
[15948.729090] [<c10b37bc>] ? sys_read+0x3c/0x63
[15948.729090] [<c10030fb>] ? sysenter_do_call+0x12/0x28
[15948.729090] Code: 03 88 46 01 8d 43 30 88 46 02 8d 45 30 c6 06 5c 88 46 03 83 c6 04 eb 0b 8b 47 04 89 47 0c 83 c8 ff eb 1e ff 44 24 04 8b 44 24 04 <0f> b6 28 89 ea 84 d2 74 06 3b 74 24 08 72 8e 2b 37 31 c0 89 77
[15948.729090] EIP: [<c10c65e4>] seq_escape+0x85/0xa3 SS:ESP 0068:f5aaff00
[15948.729090] CR2: 0000000000000000
[15948.730442] ---[ end trace f8272c1b38241fdd ]---
When shutting down my computer the system hangs and doesen't respond anymore. But no kernel panic.