Bug 14868

Created attachment 24278 [details]
dmesg from relevant system

dmesg > floodlog.txt

Created attachment 24279 [details]
2.6.31 .config

Created attachment 24280 [details]
2.6.32 .config

On Thu, 2009-12-24 at 02:44 +0000, bugzilla-daemon@bugzilla.kernel.org
wrote: 
> http://bugzilla.kernel.org/show_bug.cgi?id=14868
> 
>            Summary: flood of "don't try to register things with the same
>                     name in the same directory." on upgrade to 2.6.32
>            Product: File System
>            Version: 2.5
>     Kernel Version: 2.6.32
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: NFS
>         AssignedTo: trond.myklebust@fys.uio.no
>         ReportedBy: rercola@acm.jhu.edu
>         Regression: No
> 
> 
> Was running 2.6.31 vanilla on Fedora 10, upgraded to vanilla 2.6.32, dmesg
> started getting flooded with messages of the form [see attachment 1 [details]]:
> ------------[ cut here ]------------
> WARNING: at fs/sysfs/dir.c:491 sysfs_add_one+0x100/0x117()
> Hardware name:
> sysfs: cannot create duplicate filename '/devices/virtual/bdi/0:32'
> Modules linked in: autofs4 coretemp hwmon nfs lockd nfs_acl auth_rpcgss
> sunrpc
> cachefiles fscache ipv6 cpufreq_ondemand acpi_cpufreq freq_table kvm_intel
> kvm
> snd_hda_intel snd_hda_codec snd_seq_dummy snd_seq_oss snd_usb_audio
> snd_seq_midi_event snd_seq snd_usb_lib uvcvideo ppdev firewire_ohci
> firewire_core snd_pcm_oss snd_mixer_oss crc_itu_t pcspkr snd_rawmidi videodev
> v4l1_compat v4l2_compat_ioctl32 i2c_i801 snd_pcm i2c_core snd_seq_device
> usb_storage iTCO_wdt iTCO_vendor_support snd_hwdep snd_timer parport_pc snd
> parport e1000e i82975x_edac edac_core soundcore snd_page_alloc raid1 [last
> unloaded: scsi_wait_scan]
> Pid: 20581, comm: mount.nfs Tainted: G        W  2.6.32-fun #1
> ...
> ---[ end trace b4d582dc9db911d1 ]---
> kobject_add_internal failed for 0:32 with -EEXIST, don't try to register
> things
> with the same name in the same directory.
> Pid: 20581, comm: mount.nfs Tainted: G        W  2.6.32-fun #1
> ...
> 
> The system is indeed using autofs, so I'd blame NFS-mounts  from FreeBSD for
> this, but it wasn't cropping up in 2.6.31.

It appears to be due to the per-bdi thread changes in 2.6.32. The
support for anonymous devices has a problem in that sysfs and debugfs
directories and files can be kept open by other processes even after the
device number gets deallocated.

> I've also attached the .config for the 2.6.31 and 2.6.32 kernels, in case
> it's
> something stupid I missed.


Are you perhaps running some daemon or process that is
accessing /sys/devices/virtual/bdi/0:32 and keeping it open beyond the
lifetime of the NFS mount?

Trond

I, the system administrator, am not running anything that is persisting in that way that I know of.

I don't, at present, see any processes still living that are touching anything in /sys/devices/virtual; are there any obvious processes that I can check for, or any convenient way to monitor this? Would inotify do the right thing?

Created attachment 24901 [details]
NFS: Fix a umount race

Ensure that we unregister the bdi before kill_anon_super() calls
ida_remove() on our device name.

Does the above patch suffice to fix the bug?

Ping?

The above patch was merged for 2.6.33 and backported to 2.6.32.y.

commit: 387c149b54b4321cbc790dadbd4f8eedb5a90468