From Bugzilla Helper: User-Agent: Mozilla/4.77 [en] (X11; U; Linux 2.4.9-6 i686) Description of problem: After imapd reads an NFS-mounted mailbox, it hangs trying to release the fcntl() lock on it. An strace -p shows data being read from the mailbox and then the fcntl() call never returns. A kill -9 is needed to terminate the daemon, which then leaves .lock files behind. The process is listed as sleeping in ps. At least it's not a 'D' wait! Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: 1. Mount IMAP mailbox over NFS. 2. Try to read messages. 3. Actual Results: IMAP server hangs trying to unlock mailbox. Client eventually times out but server processes hang around until killed -9. Expected Results: The lock should have been released. Additional info: NFS mounted filesystems here are ReiserFS, not sure what happens with ext2/3. Chris Mason of SuSE thinks it's not ReiserFS-specific.
OK, I've reproduced this with the standalone flock.c from the IMAP source. I've also reproduced it with an NFS mount of an ext2 filesystem. Kernel 2.4.9-6 i686-enterprise.
We've released an update for this several days ago; 2.4.9-12 has, appart from the security fixes, also the NFS locking bug fixed. I recommend giving that a try.