Your message dated Mon, 14 Apr 2025 08:36:42 +0000
with message-id <[email protected]>
and subject line Bug#978688: fixed in procps 2:4.0.4-8
has caused the Debian Bug report #978688,
regarding /sbin/sysctl: sysctl -a stuck on vm.stat_refresh when RR tasks run
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
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--
978688: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=978688
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: procps
Version: 2:3.3.16-5
Severity: normal
File: /sbin/sysctl
X-Debbugs-Cc: [email protected]
/proc/sys/vm/stat_refresh is a special file that if read or written (by
root), triggers synchronization of all VM data from all CPUs, so other
files (i.e. /proc/meminfo in particular) show up to date values.
https://www.kernel.org/doc/Documentation/sysctl/vm.txt for more details.
sysctl -a does read this file.
strace:
strace sysctl -a 2>&1 | grep 'refresh'
stat("/proc/sys/vm/stat_refresh", {st_mode=S_IFREG|0600, st_size=0, ...}) = 0
stat("/proc/sys/vm/stat_refresh", {st_mode=S_IFREG|0600, st_size=0, ...}) = 0
openat(AT_FDCWD, "/proc/sys/vm/stat_refresh", O_RDONLY) = 5
However, in the presence of real time tasks, reading might block
indefinitively, i.e.:
sudo schedtool -R -p 98 -a 7 -e stress-ng -c 1
time cat /proc/sys/vm/stat_refresh
This will never finish (I waited dozens of minutes).
I would suggest adding a special case to sysctl to not read
vm.stat_refresh. It produces no usable output, and reading it has side
effects, thus should be avoided.
Tested on Debian kernel Linux 5.9.11 with standard settings.
Also it does feel like a regression, because I do found reports from the
past that sysctl did not read vm.stat_refresh in the past, and done so on
purpose: https://bugzilla.redhat.com/show_bug.cgi?id=1473207
As of the blocking indefinitively, I will look into contacting kernel
devs about this issue, but even if this is fixed in the kernel, the
sysctl should still not touch the /proc/sys/vm/stat_refresh file.
Regards,
Witold
-- System Information:
Debian Release: bullseye/sid
APT prefers unstable-debug
APT policy: (500, 'unstable-debug'), (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 5.9.0-4-amd64 (SMP w/32 CPU threads)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
Versions of packages procps depends on:
ii init-system-helpers 1.60
ii libc6 2.31-6
ii libncurses6 6.2+20201114-1
ii libncursesw6 6.2+20201114-1
ii libprocps8 2:3.3.16-5
ii libtinfo6 6.2+20201114-1
ii lsb-base 11.1.0
Versions of packages procps recommends:
ii psmisc 23.3-1
procps suggests no packages.
-- no debconf information
--- End Message ---
--- Begin Message ---
Source: procps
Source-Version: 2:4.0.4-8
Done: Craig Small <[email protected]>
We believe that the bug you reported is fixed in the latest version of
procps, which is due to be installed in the Debian FTP archive.
A summary of the changes between this version and the previous one is
attached.
Thank you for reporting the bug, which will now be closed. If you
have further comments please address them to [email protected],
and the maintainer will reopen the bug report if appropriate.
Debian distribution maintenance software
pp.
Craig Small <[email protected]> (supplier of updated procps package)
(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing [email protected])
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
Format: 1.8
Date: Mon, 14 Apr 2025 18:06:27 +1000
Source: procps
Architecture: source
Version: 2:4.0.4-8
Distribution: unstable
Urgency: medium
Maintainer: Craig Small <[email protected]>
Changed-By: Craig Small <[email protected]>
Closes: 729569 842879 978688 1054345 1061944 1072831 1077187 1080333 1080335
1086441 1098385
Changes:
procps (2:4.0.4-8) unstable; urgency=medium
.
* Port 4.0.5 patches:
- library: recover from meminfo seek in LXC Closes: #1072831
- library: print user/day when value is zero
- library: Use clock_gettime for pids API Closes: #842879
- kill: Correctly parse negative pids
- sysctl: Don't read some keys Closes: #978688
- skill: Fix lonesome : in help Closes: #1086441
- sysctl.conf.5 Note changes with systemd Closes: #1077187
- vmstat.8: si/so are changed by --unit Closes: #1061944
- w: Don't crash with short option Closes: #1054345
- w: Only count user sessions Closes: #1098385
- w.1: Mention utmp only for non-systemd Closes: #1080333
- watch.1: --chgexit only on visible changes Closes: #729569
* Port 4.0.6 patches:
- w: Add terminal mode -t option
- w: Use process TTY for user TTY Closes: #1080335
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