On 4/13/21 11:36 PM, Chris Schanzle via CentOS wrote: > On 4/13/21 5:00 PM, Frank Cox wrote: >> On Tue, 13 Apr 2021 22:29:26 +0200 >> Simon Matter wrote: >> >>> You could try running strace on the hanging process so see what it's doing. >> [frankcox at mutt temp]$ rsync -avv ../temp/ jeff:temp >> opening connection using: ssh jeff rsync --server -vvlogDtpre.iLsfxC . temp (7 args) >> sending incremental file list >> delta-transmission enabled >> abc is uptodate >> total: matches=0 hash_hits=0 false_alarms=0 data=0 >> >> Leaving that sit there apparently doing nothing (but still not giving me my cursor back) I switched to another terminal window and did the following: >> >> [frankcox at mutt ~]$ ps -FA | grep rsync >> frankcox 5400 2435 0 60586 3160 5 14:52 pts/0 00:00:00 rsync -avv ../temp/ jeff:temp >> frankcox 5401 5400 0 67980 7440 1 14:52 pts/0 00:00:00 ssh > jeff rsync --server -vvlogDtpre.iLsfxC . temp >> frankcox 5526 5416 0 55476 1076 3 14:53 pts/1 00:00:00 grep --color=auto rsync >> >> [frankcox at mutt ~]$ strace -p 5401 >> strace: Process 5401 attached >> select(11, [5 9 10], [], NULL, NULL >> >> Then it just sits there with no further action. I get my cursor back when I hit ctrl-c. >> >> [frankcox at mutt ~]$ strace -p 5400 >> strace: Process 5400 attached >> restart_syscall(<... resuming interrupted nanosleep ...>) = 0 >> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0 >> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0 >> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0 >> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0 >> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0 >> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0 >> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0 >> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0 >> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0 >> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0 >> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0 >> nanosleep({tv_sec=0, tv_nsec=20000000}, NULL) = 0 >> wait4(5401, 0x7ffd45105564, WNOHANG, NULL) = 0 >> >> The wait4-etc line just keeps repeating endlessly until I hit ctrl-c. >> >> Unfortunately, I have no idea what any of the above actually means. Does it tell us anything interesting? > > Yay! I am glad someone else on the planet is experiencing this. > I noticed this started happening to me after updating some CentOS Linux 8 > systems today. > > I discovered if I set ForwardX11=no (either on ssh command line or in ~/.ssh/config) the hang does not happen. But why does that matter? No updates to openssh. > > It is not the systemd update doing something silly with session management. I painfully downgraded manually and rebooted to no effect. > As an aside, why can't we we have nice things in life like 'dnf downgrade > systemd\*' actually work? I did the below - might be dumb, but it worked -- alternate suggestions to downgrade are appreciated - searching the list and my google-fu was off the mark today. > > cd [path-to-repo]/centos/8/BaseOS/x86_64/os/Packages > dnf downgrade $(rpm -qa systemd\* | grep 239-41.el8_3.2 | sed -e 's/3\.2/3.1/' -e 's/^/.\//' -e 's/$/.rpm/') > > Chris [adjusted the subject, hope that is OK.] Found it! It's the dbus update to 1.12.8-12. Downgrade to -11 and ssh connections close normally. To clarify the problem, with the new dbus, simple ssh's like: ssh somehost uptime will print the uptime, but do not return to the local shell prompt until you hit ctrl-c. It works normally if you downgrade dbus or ssh -o forwardx11=no somehost uptime I'm sure a bug report exists somewhere, but that's something to dig for or create tomorrow. To downgrade, packages were scattered in different locations, so I copied them to one directory and did dnf downgrade ./* The packages I needed to downgrade on a x86_64 system were: dbus-1.12.8-11.el8.x86_64.rpm dbus-common-1.12.8-11.el8.noarch.rpm dbus-daemon-1.12.8-11.el8.x86_64.rpm dbus-devel-1.12.8-11.el8.x86_64.rpm dbus-libs-1.12.8-11.el8.x86_64.rpm dbus-tools-1.12.8-11.el8.x86_64.rpm dbus-x11-1.12.8-11.el8.x86_64.rpm