Bionic verification "TEST A" verification was done following steps from bug #1927745, where the lack of the restart was first found, and that fix is included in this upload as well. ubuntu@b-gssd-restart-1928259-1927745-A:~$ apt-cache policy nfs-common nfs-common: Installed: 1:1.3.4-2.1ubuntu5.3 Candidate: 1:1.3.4-2.1ubuntu5.3 Version table: *** 1:1.3.4-2.1ubuntu5.3 500 500 http://br.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages 500 http://br.archive.ubuntu.com/ubuntu bionic-security/main amd64 Packages 100 /var/lib/dpkg/status 1:1.3.4-2.1ubuntu5 500 500 http://br.archive.ubuntu.com/ubuntu bionic/main amd64 Packages Problem quickly reproduced: ubuntu@b-gssd-restart-1928259-1927745-a:~$ sudo ./bz1419280_test_threads Iter 1 calling stat on '/mnt/test_krb5/foo' with uids 9995 through 10035 reproduced the bug after 1 iterations ubuntu@b-gssd-restart-1928259-1927745-a:~$ ps axw|grep stat_as 8012 pts/0 D 0:00 ./stat_as /mnt/test_krb5/foo 9995 10035 8036 pts/0 D 0:00 ./stat_as /mnt/test_krb5/foo 9995 10035 8091 pts/0 S+ 0:00 grep --color=auto stat_as In this state, I installed the fixed packages from proposed. But first, let's get the rpc.gssd pid: ubuntu@b-gssd-restart-1928259-1927745-a:~$ ps axw | grep rpc\\.gssd 7854 ? Ss 0:00 /usr/sbin/rpc.gssd Now upgrade: ubuntu@b-gssd-restart-1928259-1927745-a:~$ sudo apt install nfs-common Reading package lists... Done (...) Do you want to continue? [Y/n] Get:1 http://br.archive.ubuntu.com/ubuntu bionic-proposed/main amd64 nfs-common amd64 1:1.3.4-2.1ubuntu5.5 [206 kB] Get:2 http://br.archive.ubuntu.com/ubuntu bionic-proposed/main amd64 nfs-kernel-server amd64 1:1.3.4-2.1ubuntu5.5 [93.8 kB] Fetched 299 kB in 0s (1479 kB/s) (Reading database ... 64831 files and directories currently installed.) Preparing to unpack .../nfs-common_1%3a1.3.4-2.1ubuntu5.5_amd64.deb ... Unpacking nfs-common (1:1.3.4-2.1ubuntu5.5) over (1:1.3.4-2.1ubuntu5.3) ... Preparing to unpack .../nfs-kernel-server_1%3a1.3.4-2.1ubuntu5.5_amd64.deb ... Unpacking nfs-kernel-server (1:1.3.4-2.1ubuntu5.5) over (1:1.3.4-2.1ubuntu5.3) ... Setting up nfs-common (1:1.3.4-2.1ubuntu5.5) ... Setting up nfs-kernel-server (1:1.3.4-2.1ubuntu5.5) ... Processing triggers for man-db (2.8.3-2ubuntu0.1) ... Processing triggers for ureadahead (0.100.0-21) ... Processing triggers for systemd (237-3ubuntu10.47) ... Not only was rpc.gssd restarted automatically (see new pid): ubuntu@b-gssd-restart-1928259-1927745-a:~$ ps axw | grep rpc\\.gssd 8886 ? Ss 0:00 /usr/sbin/rpc.gssd We also got rid of the stuck stat_as processes: ubuntu@b-gssd-restart-1928259-1927745-a:~$ ps axw|grep stat_as 9550 pts/0 S+ 0:00 grep --color=auto stat_as I then ran the reproducer script one more time but aborted it manually after over 4min without hitting the bug: ubuntu@b-gssd-restart-1928259-1927745-a:~$ time sudo ./bz1419280_test_threads (...) Iter 249 calling stat on '/mnt/test_krb5/foo' with uids 9995 through 10035 ^C real 4m18.536s user 0m2.783s sys 0m5.950s TEST B ubuntu@b-gssd-restart-1928259-1927745-b:~$ diff -u pstree.old pstree.new ubuntu@b-gssd-restart-1928259-1927745-b:~$ l pstree.* -rw-rw-r-- 1 ubuntu ubuntu 633 Jun 11 20:55 pstree.new -rw-rw-r-- 1 ubuntu ubuntu 633 Jun 11 20:55 pstree.old ubuntu@b-gssd-restart-1928259-1927745-b:~$ apt-cache policy nfs-common nfs-common: Installed: 1:1.3.4-2.1ubuntu5.5 Candidate: 1:1.3.4-2.1ubuntu5.5 Version table: *** 1:1.3.4-2.1ubuntu5.5 500 500 http://br.archive.ubuntu.com/ubuntu bionic-proposed/main amd64 Packages 100 /var/lib/dpkg/status 1:1.3.4-2.1ubuntu5.3 500 500 http://br.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages 500 http://br.archive.ubuntu.com/ubuntu bionic-security/main amd64 Packages 1:1.3.4-2.1ubuntu5 500 500 http://br.archive.ubuntu.com/ubuntu bionic/main amd64 Packages Bionic verification succeeded.