Public bug reported:
/proc/sys/fs/nr_open is being bumped up to 1073741816 (instead of the
kernel default of 1048576). This, combined with a patch coming from
Debian's pam library (I'm assuming this is present in Ubuntu as well) is
causing user sessions to have a hard limit of 1073741816 files open
(RLIMIT_NOFILE). This can cause issues with applications that are
allocating memory based on the number of max file descriptors or have a
for-loop based on the number of max file descriptors.
Debian worked around this by setting -Dbump-proc-sys-fs-nr-open=false
(so the kernel default of 1048576 will stick). However, this got dropped
in Debian trixie (at least in systemd 257.8-1~deb13u2), because libpam
in Debian was updated to 1.7.0, which dropped the patch that set it to
the value in /proc/sys/fs/nr_open.
My guess is that the build rules for systemd from Debian trixie is
getting used with the older version of PAM (with the patch still
present) for Ubuntu 25.04, and so this issue is appearing now. As a data
point, Ubuntu 24.04 is fine.
Signature of issue:
$ systemctl --user -p DefaultLimitNOFILE show
DefaultLimitNOFILE=1073741816d
ProblemType: Bug
DistroRelease: Ubuntu 25.04
Package: systemd 257.4-1ubuntu3.1
Uname: Linux 6.15.2arcot-00010-g4a27874ddbf6 x86_64
ApportVersion: 2.32.0-0ubuntu5.3
Architecture: amd64
CasperMD5CheckResult: unknown
Date: Tue Nov 4 09:33:56 2025
InstallationDate: Installed on 2012-10-19 (4764 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
MachineType: Micro-Star International Co., Ltd. MS-7C94
ProcEnviron:
LANG=en_US.UTF-8@24hour
PATH=(custom, no user)
SHELL=/bin/bash
TERM=tmux-256color
XDG_RUNTIME_DIR=<set>
ProcKernelCmdLine: root=UUID=142bcd73-1a64-4a00-a377-a00d0a3c7b31 ro
rootflags=subvol=@ quiet splash kvm.ignore_msrs=1
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
systemd.machine_id=0b7990237b897ecfc2cc70af5081d7a1
SourcePackage: systemd
SystemdFailedUnits:
Error: command ['systemctl', 'status', '--full', '●'] failed with exit code 4:
Invalid unit name "●" escaped as "\xe2\x97\x8f" (maybe you should use
systemd-escape?).
Unit \xe2\x97\x8f.service could not be found.
------
Error: command ['systemctl', 'status', '--full', '●'] failed with exit code 4:
Invalid unit name "●" escaped as "\xe2\x97\x8f" (maybe you should use
systemd-escape?).
Unit \xe2\x97\x8f.service could not be found.
UpgradeStatus: Upgraded to plucky on 2015-02-28 (3902 days ago)
dmi.bios.date: 06/17/2022
dmi.bios.release: 5.17
dmi.bios.vendor: American Megatrends International, LLC.
dmi.bios.version: 1.C0
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: MAG B550M MORTAR (MS-7C94)
dmi.board.vendor: Micro-Star International Co., Ltd.
dmi.board.version: 1.0
dmi.chassis.asset.tag: To be filled by O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: Micro-Star International Co., Ltd.
dmi.chassis.version: 1.0
dmi.modalias:
dmi:bvnAmericanMegatrendsInternational,LLC.:bvr1.C0:bd06/17/2022:br5.17:svnMicro-StarInternationalCo.,Ltd.:pnMS-7C94:pvr1.0:rvnMicro-StarInternationalCo.,Ltd.:rnMAGB550MMORTAR(MS-7C94):rvr1.0:cvnMicro-StarInternationalCo.,Ltd.:ct3:cvr1.0:skuTobefilledbyO.E.M.:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: MS-7C94
dmi.product.sku: To be filled by O.E.M.
dmi.product.version: 1.0
dmi.sys.vendor: Micro-Star International Co., Ltd.
** Affects: systemd (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug plucky
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https://bugs.launchpad.net/bugs/2130664
Title:
User process have a max file limit of 1073741816 (2^30), caused by
missing change from Debian
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