[fuse-devel] deadlock on amd64

[Patrick2000 <pat...@ma...>]

Hi all

I have an issue where some kind of deadlock (i suppose) is causing any process
trying to access a fuse mounted directory to block forever.

It happens only on amd64 platform.
To reproduce, install wuala (www.wuala.com), run it with a 32bit java virtual
machine ("apt-get install ia32-sun-java6-bin";
"JAVA=/usr/lib/jvm/ia32-java-6-sun/jre/bin/java wuala"), enable file system
integration (tools - options - ...), exit, run with 64bit java vm
("wuala -nogui").

That causes wuala to load libwualafs64.so, which loads libfuse.so.2.

libfuse.so.2 forks to execute /bin/fusermount
(fuse_main() -> fuse_setup() -> fuse_mount())

/bin/fusermount does a mount() syscall and then forks to execute
"/bin/mount -f ..."

/bin/mount does a readlink("mountpoint") syscall which never returns, leaves
/bin/fusermount and /bin/mount lingering around in a sleeping state and any
process trying to access the mountpoint is blocked thereafter (can't be
"kill -KILL"'ed - you have to "kill -KILL mount fusermount" and
"umount [mountpoint]" to get back to a working system)

As mentioned, this doesn't happen on a 32-bit platform.

Still, I actually wonder, why in fuse_setup_common() fuse_mount_common() is
actually called before fuse_new_common() - which might imho be part of the
problem?

Thank's for any feedback

Cheers