From: NeilBrown <neilb@suse.de>

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 fs/nfsd/nfsctl.c |    2 ++
 1 files changed, 2 insertions(+)

diff -puN fs/nfsd/nfsctl.c~knfsd-protect-update-to-sn_nrthreads-with-lock_kernel fs/nfsd/nfsctl.c
--- a/fs/nfsd/nfsctl.c~knfsd-protect-update-to-sn_nrthreads-with-lock_kernel
+++ a/fs/nfsd/nfsctl.c
@@ -532,7 +532,9 @@ static ssize_t write_ports(struct file *
 			/* Decrease the count, but don't shutdown the
 			 * the service
 			 */
+			lock_kernel();
 			nfsd_serv->sv_nrthreads--;
+			unlock_kernel();
 		}
 		return err;
 	}
_