I am still seeing this problem on Ubuntu 9.10. The real problem is that when this happens (as near as I can tell), my system becomes unresponsive to network traffic. However, when I go to the console (via KVM) and simply press enter, everything returns to normal.

This happens intermittently, often (it seems) around midnight. I am running dovecot imap, and that would seem to be involved in the information below. There was another bug reported with nearly indentical details as below and involving dovecot.

I am running a server in this case, no gdm but lots of other usual server things (apache, postfix, mysql, dovecot, etc). I need this system to be reliable, and despite apparent reports that this problem was fixed in 2.6.31-6, clearly it has not been. 

So I offer this data point in the hopes that it is helpful, and in the hope that this issue get some increased priority and gets fixed once and for all! (For what it's worth, I also run Ubuntu 9.10 on a laptop and on a system at work, and neither suffer from this. But then, neither of those systems runs dovecot or any other server-like stuff.

If there is more information I can provide, I am happy to do so. Just contact me. mark at granoff dot net

$ uname -a
Linux opus 2.6.31-16-generic #52-Ubuntu SMP Thu Dec 3 22:00:22 UTC 2009 i686 GNU/Linux

From kern.log:

Dec  9 00:16:58 opus kernel: [147655.680560] ------------[ cut here ]------------
Dec  9 00:16:58 opus kernel: [147655.680583] WARNING: at /build/buildd/linux-2.6.31/fs/notify/inotify/inotify_fsnotify.c:129 idr_callback+0x4f/0x80()
Dec  9 00:16:58 opus kernel: [147655.680588] Hardware name: A7V400-MX
Dec  9 00:16:58 opus kernel: [147655.680592] inotify closing but id=0 for entry=ef9c6840 in group=f6346580 still in idr.  Probably leaking memory
Dec  9 00:16:58 opus kernel: [147655.680596] Modules linked in: snd_via82xx snd_ac97_codec iptable_filter ip_tables i2c_viapro ac97_bus snd_pcm_oss snd_mixer_oss snd_pcm snd_page_alloc snd_mpu401_uart snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer snd_seq_device x_tables lp snd via_ircc irda soundcore ns558 gameport via_agp ppdev parport_pc parport shpchp agpgart crc_ccitt raid10 raid456 raid6_pq async_xor async_memcpy async_tx xor raid1 raid0 multipath linear via_rhine mii
Dec  9 00:16:58 opus kernel: [147655.680647] Pid: 3969, comm: imap Not tainted 2.6.31-16-generic #52-Ubuntu
Dec  9 00:16:58 opus kernel: [147655.680651] Call Trace:
Dec  9 00:16:58 opus kernel: [147655.680666]  [<c014518d>] warn_slowpath_common+0x6d/0xa0
Dec  9 00:16:58 opus kernel: [147655.680672]  [<c021620f>] ? idr_callback+0x4f/0x80
Dec  9 00:16:58 opus kernel: [147655.680676]  [<c021620f>] ? idr_callback+0x4f/0x80
Dec  9 00:16:58 opus kernel: [147655.680682]  [<c0145206>] warn_slowpath_fmt+0x26/0x30
Dec  9 00:16:58 opus kernel: [147655.680686]  [<c021620f>] idr_callback+0x4f/0x80
Dec  9 00:16:58 opus kernel: [147655.680694]  [<c0310fc6>] idr_for_each+0x76/0xd0
Dec  9 00:16:58 opus kernel: [147655.680699]  [<c02161c0>] ? idr_callback+0x0/0x80
Dec  9 00:16:58 opus kernel: [147655.680704]  [<c0214357>] ? fsnotify_put_event+0x37/0x50
Dec  9 00:16:58 opus kernel: [147655.680709]  [<c0214401>] ? fsnotify_flush_notify+0x91/0xa0
Dec  9 00:16:58 opus kernel: [147655.680717]  [<c0570ef8>] ? _spin_lock+0x8/0x10
Dec  9 00:16:58 opus kernel: [147655.680721]  [<c02161a5>] inotify_free_group_priv+0x15/0x30
Dec  9 00:16:58 opus kernel: [147655.680726]  [<c0214479>] fsnotify_final_destroy_group+0x19/0x30
Dec  9 00:16:58 opus kernel: [147655.680731]  [<c0214567>] fsnotify_put_group+0x77/0x80
Dec  9 00:16:58 opus kernel: [147655.680736]  [<c0216401>] inotify_release+0x21/0x40
Dec  9 00:16:58 opus kernel: [147655.680744]  [<c01e915a>] __fput+0xda/0x1f0
Dec  9 00:16:58 opus kernel: [147655.680748]  [<c01e9285>] fput+0x15/0x20
Dec  9 00:16:58 opus kernel: [147655.680753]  [<c01e56a7>] filp_close+0x47/0x70
Dec  9 00:16:58 opus kernel: [147655.680757]  [<c01e5743>] sys_close+0x73/0xb0
Dec  9 00:16:58 opus kernel: [147655.680763]  [<c010336c>] syscall_call+0x7/0xb
Dec  9 00:16:58 opus kernel: [147655.680767] ---[ end trace 8fc4ecd1bdfbb6f4 ]---
Dec  9 00:16:58 opus kernel: [147655.680771] entry->group=(null) inode=(null) wd=1024