umount NFS share fails with SIGABRT when root is in > 16 groups

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Environment

SUSE Linux Enterprise Server 11 Service Pack 1

Situation

If root is in more than 16 groups, unmounting NFS mounts will fail. After "umount /nfs-share" the nfs mount remains mounted and "mount" will show it in the mount list.

A strace ('strace -v -o umount.strace umount /nfs-share') of the umount documents the failure with the following error:

....
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb76b4bb8) = 5009
wait4(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGABRT}], 0, NULL) = 5009
--- SIGCHLD (Child exited) @ 0 (0) ---

The reason of the problem is described here: git.linux-nfs.org

Resolution

The nfs-client update to version -1.2.1-2.12.1 includes the patch correcting the problem.

Disclaimer

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