Leaking sessions in pam_systemd

[non7top]

May 19 12:38:38 s20.wr0.ru sshd[3793128]: pam_systemd(sshd:session): Failed to create session: Maximum number of sessions (8192) reached, refusing further sessions.

# loginctl list-sessions|wc -l
8195

 # loginctl session-status 302548700
302548700 - topaz (450)
           Since: Tue 2022-10-18 09:29:02; 7 months 0 days ago
          Leader: 2637625
          Remote: 92.42.15.122
         Service: sshd; type tty; class user
           State: closing
            Unit: session-302548700.scope

# ps axf|wc -l
72

The only way I could figure to fix this is to reboot.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: systemd 245.4-4ubuntu3.21
Uname: Linux 4.15.0 x86_64
ApportVersion: 2.20.11-0ubuntu27.26
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDmesg:

Date: Fri May 19 12:58:47 2023
Lsusb: Error: [Errno 2] No such file or directory: 'lsusb'
Lsusb-t: Error: [Errno 2] No such file or directory: 'lsusb'
Lsusb-v: Error: [Errno 2] No such file or directory: 'lsusb'
ProcEnviron:
 SHELL=/bin/bash
 LANG=en_US.utf8
 TERM=xterm-256color
 PATH=(custom, no user)
ProcInterrupts: Error: [Errno 2] No such file or directory: '/proc/interrupts'
ProcKernelCmdLine: quiet
SourcePackage: systemd
UpgradeStatus: Upgraded to focal on 2022-01-26 (478 days ago)
acpidump:

mtime.conffile..etc.systemd.journald.conf: 2022-08-19T16:13:27.570934

[Nick Rosbrook (enr0n)]

What makes you say the sessions are "leaked", exactly? Is there something odd about the sessions listed? I realize that is a large number, however.

[non7top (non7top)]

Well. I don't see any processes in the OS that would correspond to those sessions. The state of most of them is Closing. systemd also spams a lot about too many sessions. Looks like systemd doesn't close sessions properly.

[Nick Rosbrook (enr0n)]

Can you please attach logs from a boot where this was seen? If the current boot exhibits this, you can use 0 as the boot id:

$ journalctl -u systemd-logind.service -b $boot_id > systemd-logind-logs.txt

[non7top (non7top)]

Not sure what the "boot" is, but here are the outputs from the same system:

# journalctl -u systemd-logind.service -b 0
-- Logs begin at Tue 2023-06-13 11:39:06 MSK, end at Tue 2023-06-13 12:44:33 MSK. --
-- No entries --

# loginctl session-status 302548700
302548700 - topaz (450)
           Since: Tue 2022-10-18 09:29:02 MSK; 7 months 25 days ago
          Leader: 2637625
          Remote: 92.42.15.122
         Service: sshd; type tty; class user
           State: closing
            Unit: session-302548700.scope
# loginctl list-sessions|wc -l
8195

[non7top (non7top)]

Could be this bug
https://github.com/systemd/systemd/issues/8672

[non7top (non7top)]

My systemd reports

# systemd --version
systemd 245 (245.4-4ubuntu3.21)
+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN2 -IDN +PCRE2 default-hierarchy=hybrid

[Nick Rosbrook (enr0n)]

You don't have any logs for systemd-logind? Have you modified the log level at some point? I guess that bug does sound similar, but it is unclear and there is no real resolution on that bug.