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Posodobljeno: 35 min 22 sec nazaj
Pon, 05/09/2022 - 21:35
The problem of negative dentries accumulating in the dentry cache in an
unbounded manner, as we
looked at back in
April, came up at the
2022 Linux Storage,
Filesystem, Memory-management and BPF Summit (LSFMM).
Negative dentries reflect failed file-name lookups, which are then cached,
saving an expensive operation if the file name in question is looked up
again. There is no mechanism to proactively prune back those cache
entries, however, so the cache keeps growing until memory pressure finally
causes the system to forcibly evict some of them, which can make the system
unresponsive for a long time or even cause a soft lockup.
Pon, 05/09/2022 - 14:38
One of the memory-management subsystem's most important jobs is reclaiming
unused (or
little-used) memory so that it can be put to better use. When it comes to
one of the core memory-management data structures — page tables — though,
this subsystem often falls down on the job. At the
2022 Linux Storage,
Filesystem, Memory-management and BPF Summit (LSFMM), David Hildenbrand led a
session on the problems posed by the lack of page-table reclaim and
explored options for improving the situation.
Pon, 05/09/2022 - 14:05
Greg Kroah-Hartman has announced the release of the
5.17.6,
5.15.38,
5.10.114, and
5.4.192 stable kernels. As usual, these
contain important fixes throughout the tree; users of those series should upgrade.
Pon, 05/09/2022 - 13:54
Security updates have been issued by CentOS (firefox and thunderbird), Debian (ecdsautils and libz-mingw-w64), Fedora (cifs-utils, firefox, galera, git, java-1.8.0-openjdk, java-11-openjdk, java-17-openjdk, java-latest-openjdk, mariadb, maven-shared-utils, mingw-freetype, redis, and seamonkey), Mageia (dcraw, firefox, lighttpd, rsyslog, ruby-nokogiri, and thunderbird), Scientific Linux (thunderbird), SUSE (giflib, kernel, and libwmf), and Ubuntu (dbus and rsyslog).
Pon, 05/09/2022 - 01:10
The
5.18-rc6 kernel prepatch is out for
testing. "Please do go test it all out - because things may look
good now, but continued testing is the only thing that will make
sure."
Pet, 05/06/2022 - 17:52
The
GCC project has made the first release of the GCC 12 series,
GCC 12.1. As the announcement notes, this month is the 35th anniversary of the GCC 1.0 release. There are lots of changes and fixes in this release, including:
This release deprecates support for the STABS debugging format and
introduces support for the
CTF debugging format. The C and C++
frontends continue to advance with extending support for features
in the upcoming C2X and C++23 standards and the C++ standard library
improves support for the experimental C++20 and C++23 parts.
The Fortran frontend now fully supports TS 29113 for interoperability with C.
[...] On the security side GCC can now initialize stack variables implicitly
using -ftrivial-auto-var-init to help tracking down and mitigating
uninitialized stack variable flaws. The C and C++ frontends now support
__builtin_dynamic_object_size compatible with the clang extension.
The x86 backend gained mitigations against straight line speculation
with -mharden-sls. The experimental Static Analyzer gained uninitialized
variable use detection and many other improvements.
Pet, 05/06/2022 - 15:59
There are certain themes that recur regularly at the Linux Storage,
Filesystem, Memory-Management, and BPF Summit; among the most reliable is
the scalability problems posed by the mmap_lock (formerly
mmap_sem) lock. This topic has come up in (at least)
2013,
2018 (
twice),
and
2019. The
2022 event was no
exception, with three consecutive sessions led by Liam Howlett, Michel
Lespinasse, and Suren Baghdasaryan
dedicated to the topic. There are improvements on the horizon, but the problem
is far from solved.
Pet, 05/06/2022 - 14:34
Security updates have been issued by Debian (dpdk, mruby, openjdk-11, and smarty3), Oracle (thunderbird), Red Hat (thunderbird), SUSE (chromium, libvirt, python-Twisted, and tar), and Ubuntu (cron and jbig2dec).
Čet, 05/05/2022 - 14:25
"Hardware poisoning" is a mechanism for detecting and handling memory
errors in a running system. When a particular range of memory ceases to
remember correctly, it is "poisoned" and further accesses to it will
generate errors. The kernel has had
support for
hardware poisoning for over a decade, but that doesn't mean it can't be
improved. At the
2022 Linux Storage,
Filesystem, Memory-management and BPF Summit, Yang Shi discussed the
challenges of dealing with hardware poisoning when it affects memory used
for the page cache.
Čet, 05/05/2022 - 14:18
Security updates have been issued by Debian (firefox-esr), Fedora (firefox, java-1.8.0-openjdk, java-11-openjdk, java-17-openjdk, java-latest-openjdk, recutils, suricata, and zchunk), Oracle (firefox and kernel), Red Hat (firefox), Scientific Linux (firefox), Slackware (mozilla, openssl, and seamonkey), SUSE (apache2-mod_auth_mellon, libvirt, and pgadmin4), and Ubuntu (dpdk, mysql-5.7, networkd-dispatcher, openssl, openssl1.0, sqlite3, and twisted).
Čet, 05/05/2022 - 04:05
The LWN.net Weekly Edition for May 5, 2022 is available.
Sre, 05/04/2022 - 23:34
There is a lot of work going on right now on speeding up Python; Kevin
Modzelewski gave a presentation at
PyCon 2022 on some of that
work. Much of it has implications for Python programmers in terms of how
to best take advantage of these optimizations in their code. He gave an
overview of some of the projects, the kinds of optimizations being worked
on, and provided some benchmarks to give a general idea of how much faster
various Python implementations are getting—and which operations are most affected.
Sre, 05/04/2022 - 14:36
The
folio project is not yet two years old,
but it has already resulted in
significant changes to the kernel's memory-management and filesystem
layers. While much work has been done, quite a bit remains. In the
opening plenary session at the
2022 Linux Storage,
Filesystem, Memory-management and BPF Summit, Matthew Wilcox provided
an update on the folio transition and led a discussion on the work that
remains to be done.
Sre, 05/04/2022 - 14:33
Security updates have been issued by Debian (openjdk-17), Fedora (chromium and suricata), Oracle (mariadb:10.5), SUSE (amazon-ssm-agent, containerd, docker, java-11-openjdk, libcaca, libwmf, pcp, ruby2.5, rubygem-puma, webkit2gtk3, and xen), and Ubuntu (linux-raspi).
Sre, 05/04/2022 - 01:09
Version
100.0 of the Firefox browser has been released. New features include
video caption display on various proprietary sites, multiple-language
spelling checking, invisible scrollbars, and more.
Tor, 05/03/2022 - 20:52
Python's match statement, which provides a long-sought C-like
switch statement—though it is far more than that—has now been part of the
language for more than six months. One of the authors of the series of Python
Enhancement Proposals (PEPs) that described the
feature, Brandt Bucher, came to
PyCon 2022 in Salt Lake City, Utah to talk
about
the feature. He gave an overview of its history, some of its many-faceted
abilities, a bit about how it was implemented, and some thoughts on its
future, in a presentation on
April 29, which was the first day of talks for the conference.
Tor, 05/03/2022 - 14:53
Version 4.7 of the SystemTap tracing system is out. "Enhancements to this release include: a new stap-profile-annotate
tool, a new --sign-module module signing option, -d is now implied for
processes specified with -c/-x".
Tor, 05/03/2022 - 14:51
Security updates have been issued by Debian (jackson-databind, kernel, openvpn, and twisted), Fedora (xz), Mageia (chromium-browser-stable and curl), Oracle (vim and xmlrpc-c), Red Hat (gzip), Slackware (libxml2), SUSE (git, python39, and subversion), and Ubuntu (libvirt and mysql-5.7, mysql-8.0).
Pon, 05/02/2022 - 15:31
The classic NUMA architecture is built around nodes, each of which contains
a set of CPUs and some local memory; all nodes are more-or-less equal.
Recently, though, "tiered-memory" NUMA systems have begun to appear; these
include CPU-less nodes that contain persistent memory rather than (faster,
but more expensive) DRAM. One possible use for that
memory is to hold less-frequently-used pages rather than forcing them out
to a backing-store device. There is an interesting problem that emerges
from this use case, though: how does the kernel manage the movement of
pages between faster and slower memory? Several recent patch sets have
taken differing approaches to the problem of rebalancing memory on these
systems.
Pon, 05/02/2022 - 15:02
Richard Hughes
announces
the fwupd 1.8.0 release and notes that the associated
Linux Vendor Firmware Service has now shipped
a minimum of 50 million firmware updates.
Just 7 years ago Christian asked me to “make firmware updates work
on Linux” and now we have a thriving client project that respects
both your freedom and your privacy, and a thriving ecosystem of
hardware vendors who consider Linux users first class citizens. Of
course, there are vendors who are not shipping updates for popular
hardware, but they’re now in the minority — and every month we have
two or three new vendor account requests.