Messages in this thread | | | Date | Thu, 25 Mar 1999 09:56:16 +0100 | From | Ruben Schattevoy <> | Subject | kernel freeze after "lockd: attempt to release unknown file!" |
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Hi,
on 21st of March I posted an emergency message concerning a quite reproduceable kernel freeze of the recent kernel. Since I did not get any response, I try to explain the problem once more.
Here again the main statement of that posting:
--- previous positing starts here ---
I experienced several system freezes in the last days (SuSE 6.0, glibc, SMP kernel-nfs, kernel 2.2.2 and 2.2.3-ac3). Apparently these freezes happen under heavy NFS traffic. More precise, from the last lines found in the message file I conclude it might be a problem which is NFS-lockd related. I appended the last minute of the message file from the last three crashes. The last message is in any case:
kernel: lockd: attempt to release unknown file!
--- previous positing ends here ---
In the mean time I successfully checked that the program which tends to crash the nfs-server works perfectly fine with the working directory being located on a Solaris nfs-server rather than a Linux nfs-server.
Could someone tell me, what this kernel message "lockd: attempt to release unknown file!" means? Is it a diagnostic, warning or error message? As I said, I find this message in the message file from time to time. And not always the kernel freezes right after that message.
I would be happy to do any testing in order to trace down the bug. I mean things like including some debug print out in the kernel. But I would need assistence from kernel hackers to do so.
The only hint I can give to give you a clue what the system is doing when it crashes is, that several ten (maybe 50 or 100) processes on ten attached number crunchers start at about the same time to create files and directories on the common nfs-mounted directory. About 120 files and 80 directories and sub-directories in about one minute. These processes also make havy use of lockf system calls to synchronize their activities. Finally, there are quite some symlinks to be followed by the nfs-server at the moment of kernel freeze. The latter might be a problem, since the number of nested symlinks is limitted to 5 in the kernel source (hard coded, not a well define parameter!). This magic number of 5 nested symlinks might indicate that the kernel cannot cope with too many concurrent processes which want to resolve nested symlinks at a time? Just an idea, of course...
As it might have become evident, I'm talking about a quite big project which is based on Linux. Whether I can solve that problem or not, will be of general interested and importance, I guess.
Thanks,
Ruben
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