From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- scripts/ver_linux | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100755 scripts/ver_linux (limited to 'scripts/ver_linux') diff --git a/scripts/ver_linux b/scripts/ver_linux new file mode 100755 index 000000000..00bdaf30d --- /dev/null +++ b/scripts/ver_linux @@ -0,0 +1,97 @@ +#!/usr/bin/awk -f +# SPDX-License-Identifier: GPL-2.0 +# Before running this script please ensure that your PATH is +# typical as you use for compilation/installation. I use +# /bin /sbin /usr/bin /usr/sbin /usr/local/bin, but it may +# differ on your system. + +BEGIN { + usage = "If some fields are empty or look unusual you may have an old version.\n" + usage = usage "Compare to the current minimal requirements in Documentation/process/changes.rst\n" + print usage + + system("uname -a") + printf("\n") + + vernum = "[0-9]+([.]?[0-9]+)+" + libc = "libc[.]so[.][0-9]+$" + libcpp = "(libg|stdc)[+]+[.]so([.][0-9]+)+$" + + printversion("bash", version("bash --version")) + printversion("bc", version("bc --version")) + printversion("bindgen", version("bindgen --version")) + printversion("binutils", version("ld -v")) + printversion("bison", version("bison --version")) + printversion("btrfs-progs", version("btrfs --version")) + printversion("Clang", version("clang --version")) + printversion("Console-tools", version("loadkeys -V")) + printversion("Dynamic linker (ldd)", version("ldd --version")) + printversion("e2fsprogs", version("e2fsck -V")) + printversion("flex", version("flex --version")) + printversion("gdb", version("gdb -version")) + printversion("GNU awk", version("gawk --version")) + printversion("GNU C", version("gcc -dumpversion")) + printversion("GNU make", version("make --version")) + printversion("GNU tar", version("tar --version")) + printversion("GRUB2", version("grub2-install --version")) + printversion("GRUB", version("grub-install --version")) + printversion("gtags", version("gtags --version")) + printversion("iptables", version("iptables -V")) + printversion("Isdn4k-utils", version("isdnctrl")) + printversion("jfsutils", version("fsck.jfs -V")) + printversion("Kbd", version("loadkeys -V")) + printversion("kmod", version("kmod -V")) + + while ("ldconfig -p 2>/dev/null" | getline > 0) + if ($NF ~ libc || $NF ~ libcpp) + if (!seen[ver = version("readlink " $NF)]++) + printversion("Linux C" ($NF ~ libcpp? "++" : "") " Library", ver) + + printversion("mcelog", version("mcelog --version")) + printversion("mkimage", version("mkimage --version")) + printversion("Module-init-tools", version("depmod -V")) + printversion("Mount", version("mount --version")) + printversion("Net-tools", version("ifconfig --version")) + printversion("nfs-utils", version("showmount --version")) + printversion("openssl", version("openssl version")) + printversion("pahole", version("pahole --version")) + printversion("Pcmcia-cs", version("cardmgr -V")) + printversion("pcmciautils", version("pccardctl -V")) + printversion("PPP", version("pppd --version")) + printversion("procps", version("ps --version")) + printversion("Python", version("python3 -V")) + printversion("quota-tools", version("quota -V")) + printversion("Rust", version("rustc --version")) + printversion("Sh-utils", version("expr --v")) + printversion("Sphinx", version("sphinx-build --version")) + printversion("squashfs-tools", version("mksquashfs -version")) + printversion("udev", version("udevadm --version")) + printversion("util-linux", version("mount --version")) + printversion("Wireless-tools", version("iwconfig --version")) + printversion("xfsprogs", version("xfs_db -V")) + + while ("sort /proc/modules" | getline > 0) { + mods = mods sep $1 + sep = " " + } + printversion("Modules Loaded", mods) +} + +function version(cmd, ver) { + cmd = cmd " 2>&1" + while (cmd | getline > 0) { + if (match($0, vernum)) { + ver = substr($0, RSTART, RLENGTH) + break + } + } + close(cmd) + return ver +} + +function printversion(name, value, ofmt) { + if (value != "") { + ofmt = "%-20s\t%s\n" + printf(ofmt, name, value) + } +} -- cgit v1.3.1