FUSE sometimes freezes, making it impossible to unmount the filesystem or even kill the processes accessing it

[Dima Ryazanov]

I had a directory mounted using sshfs. When I disconnected from the network, sshfs froze, making it impossible to unmount the directory. "fusermount -u" complained that the filesystem was busy. "fusermount -z -u" appeared to unmount it - but all programs that were accessing it earlier were still frozen. Killing the "sshfs" process didn't help. I can't even kill any of the programs that froze - they're stuck in uninterruptible sleep.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: fuse 2.8.6-2ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-29.46+kamal5~DellXPS-generic 3.2.24
Uname: Linux 3.2.0-29-generic x86_64
ApportVersion: 2.0.1-0ubuntu11
Architecture: amd64
Date: Thu Aug 2 11:54:48 2012
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
ProcEnviron:
 TERM=xterm
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: fuse
UpgradeStatus: No upgrade log present (probably fresh install)

[Dima Ryazanov (dima-gmail)]

It also prevents the system from suspending:

Aug 7 20:31:29 dima-xps kernel: [28554.059134] Freezing of tasks failed after 20.00 seconds (1 tasks refusing to freeze, wq_busy=0):
Aug 7 20:31:29 dima-xps kernel: [28554.059203] gedit D 0000000000000001 0 6819 1 0x00800004
Aug 7 20:31:29 dima-xps kernel: [28554.059207] ffff8800546d9a18 0000000000000082 ffffffff81079fbb ffff88006725dc00
Aug 7 20:31:29 dima-xps kernel: [28554.059211] ffff8800546d9fd8 ffff8800546d9fd8 ffff8800546d9fd8 0000000000013780
Aug 7 20:31:29 dima-xps kernel: [28554.059214] ffff8800b30f0000 ffff88006725dc00 ffff8800546d9a28 ffff8801150d3b60
Aug 7 20:31:29 dima-xps kernel: [28554.059218] Call Trace:
Aug 7 20:31:29 dima-xps kernel: [28554.059225] [<ffffffff81079fbb>] ? recalc_sigpending+0x1b/0x50
Aug 7 20:31:29 dima-xps kernel: [28554.059230] [<ffffffff816579cf>] schedule+0x3f/0x60
Aug 7 20:31:29 dima-xps kernel: [28554.059235] [<ffffffff81278c15>] request_wait_answer+0x85/0x230
Aug 7 20:31:29 dima-xps kernel: [28554.059238] [<ffffffff8108aa50>] ? add_wait_queue+0x60/0x60
Aug 7 20:31:29 dima-xps kernel: [28554.059241] [<ffffffff81278e35>] fuse_request_send+0x75/0xb0
Aug 7 20:31:29 dima-xps kernel: [28554.059244] [<ffffffff8127d56d>] fuse_dentry_revalidate+0x14d/0x280
Aug 7 20:31:29 dima-xps kernel: [28554.059248] [<ffffffff8118485b>] do_lookup+0x18b/0x310
Aug 7 20:31:29 dima-xps kernel: [28554.059251] [<ffffffff8129c8ac>] ? security_inode_permission+0x1c/0x30
Aug 7 20:31:29 dima-xps kernel: [28554.059254] [<ffffffff811851d8>] link_path_walk+0x138/0x870
Aug 7 20:31:29 dima-xps kernel: [28554.059256] [<ffffffff8118641d>] ? path_init+0x2ed/0x3c0
Aug 7 20:31:29 dima-xps kernel: [28554.059259] [<ffffffff81186548>] path_lookupat+0x58/0x750
Aug 7 20:31:29 dima-xps kernel: [28554.059263] [<ffffffff81318db7>] ? __strncpy_from_user+0x27/0x60
Aug 7 20:31:29 dima-xps kernel: [28554.059266] [<ffffffff81186c71>] do_path_lookup+0x31/0xc0
Aug 7 20:31:29 dima-xps kernel: [28554.059268] [<ffffffff81187779>] user_path_at_empty+0x59/0xa0
Aug 7 20:31:29 dima-xps kernel: [28554.059273] [<ffffffff811b6152>] ? fsnotify+0x1c2/0x2a0
Aug 7 20:31:29 dima-xps kernel: [28554.059276] [<ffffffff81659bc5>] ? _raw_spin_lock_irq+0x15/0x20
Aug 7 20:31:29 dima-xps kernel: [28554.059278] [<ffffffff811877d1>] user_path_at+0x11/0x20
Aug 7 20:31:29 dima-xps kernel: [28554.059282] [<ffffffff8117c80a>] vfs_fstatat+0x3a/0x70
Aug 7 20:31:29 dima-xps kernel: [28554.059284] [<ffffffff8117c85e>] vfs_lstat+0x1e/0x20
Aug 7 20:31:29 dima-xps kernel: [28554.059287] [<ffffffff8117c9fa>] sys_newlstat+0x1a/0x40
Aug 7 20:31:29 dima-xps kernel: [28554.059289] [<ffffffff81177ba0>] ? vfs_write+0x110/0x180
Aug 7 20:31:29 dima-xps kernel: [28554.059292] [<ffffffff81177e87>] ? sys_write+0x67/0x90
Aug 7 20:31:29 dima-xps kernel: [28554.059295] [<ffffffff81661ec2>] system_call_fastpath+0x16/0x1b
Aug 7 20:31:29 dima-xps kernel: [28554.059319]
Aug 7 20:31:29 dima-xps kernel: [28554.059320] Restarting tasks ...

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.