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/extract-module-sig.pl | 138 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 138 insertions(+) create mode 100755 scripts/extract-module-sig.pl (limited to 'scripts/extract-module-sig.pl') diff --git a/scripts/extract-module-sig.pl b/scripts/extract-module-sig.pl new file mode 100755 index 000000000..36a2f59c4 --- /dev/null +++ b/scripts/extract-module-sig.pl @@ -0,0 +1,138 @@ +#!/usr/bin/env perl +# SPDX-License-Identifier: GPL-2.0 +# +# extract-mod-sig +# +# Reads the module file and writes out some or all of the signature +# section to stdout. Part is the bit to be written and is one of: +# +# -0: The unsigned module, no signature data at all +# -a: All of the signature data, including magic number +# -d: Just the descriptor values as a sequence of numbers +# -n: Just the signer's name +# -k: Just the key ID +# -s: Just the crypto signature or PKCS#7 message +# +use warnings; +use strict; + +die "Format: $0 -[0adnks] module-file >out\n" + if ($#ARGV != 1); + +my $part = $ARGV[0]; +my $modfile = $ARGV[1]; + +my $magic_number = "~Module signature appended~\n"; + +# +# Read the module contents +# +open FD, "<$modfile" || die $modfile; +binmode(FD); +my @st = stat(FD); +die "$modfile" unless (@st); +my $buf = ""; +my $len = sysread(FD, $buf, $st[7]); +die "$modfile" unless (defined($len)); +die "Short read on $modfile\n" unless ($len == $st[7]); +close(FD) || die $modfile; + +print STDERR "Read ", $len, " bytes from module file\n"; + +die "The file is too short to have a sig magic number and descriptor\n" + if ($len < 12 + length($magic_number)); + +# +# Check for the magic number and extract the information block +# +my $p = $len - length($magic_number); +my $raw_magic = substr($buf, $p); + +die "Magic number not found at $len\n" + if ($raw_magic ne $magic_number); +print STDERR "Found magic number at $len\n"; + +$p -= 12; +my $raw_info = substr($buf, $p, 12); + +my @info = unpack("CCCCCxxxN", $raw_info); +my ($algo, $hash, $id_type, $name_len, $kid_len, $sig_len) = @info; + +if ($id_type == 0) { + print STDERR "Found PGP key identifier\n"; +} elsif ($id_type == 1) { + print STDERR "Found X.509 cert identifier\n"; +} elsif ($id_type == 2) { + print STDERR "Found PKCS#7/CMS encapsulation\n"; +} else { + print STDERR "Found unsupported identifier type $id_type\n"; +} + +# +# Extract the three pieces of info data +# +die "Insufficient name+kid+sig data in file\n" + unless ($p >= $name_len + $kid_len + $sig_len); + +$p -= $sig_len; +my $raw_sig = substr($buf, $p, $sig_len); +$p -= $kid_len; +my $raw_kid = substr($buf, $p, $kid_len); +$p -= $name_len; +my $raw_name = substr($buf, $p, $name_len); + +my $module_len = $p; + +if ($sig_len > 0) { + print STDERR "Found $sig_len bytes of signature ["; + my $n = $sig_len > 16 ? 16 : $sig_len; + foreach my $i (unpack("C" x $n, substr($raw_sig, 0, $n))) { + printf STDERR "%02x", $i; + } + print STDERR "]\n"; +} + +if ($kid_len > 0) { + print STDERR "Found $kid_len bytes of key identifier ["; + my $n = $kid_len > 16 ? 16 : $kid_len; + foreach my $i (unpack("C" x $n, substr($raw_kid, 0, $n))) { + printf STDERR "%02x", $i; + } + print STDERR "]\n"; +} + +if ($name_len > 0) { + print STDERR "Found $name_len bytes of signer's name [$raw_name]\n"; +} + +# +# Produce the requested output +# +if ($part eq "-0") { + # The unsigned module, no signature data at all + binmode(STDOUT); + print substr($buf, 0, $module_len); +} elsif ($part eq "-a") { + # All of the signature data, including magic number + binmode(STDOUT); + print substr($buf, $module_len); +} elsif ($part eq "-d") { + # Just the descriptor values as a sequence of numbers + print join(" ", @info), "\n"; +} elsif ($part eq "-n") { + # Just the signer's name + print STDERR "No signer's name for PKCS#7 message type sig\n" + if ($id_type == 2); + binmode(STDOUT); + print $raw_name; +} elsif ($part eq "-k") { + # Just the key identifier + print STDERR "No key ID for PKCS#7 message type sig\n" + if ($id_type == 2); + binmode(STDOUT); + print $raw_kid; +} elsif ($part eq "-s") { + # Just the crypto signature or PKCS#7 message + binmode(STDOUT); + print $raw_sig; +} -- cgit v1.3.1