From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- .../postprocess/trace-pagealloc-postprocess.pl | 418 +++++++++++++++++++++ 1 file changed, 418 insertions(+) create mode 100644 Documentation/trace/postprocess/trace-pagealloc-postprocess.pl (limited to 'Documentation/trace/postprocess/trace-pagealloc-postprocess.pl') diff --git a/Documentation/trace/postprocess/trace-pagealloc-postprocess.pl b/Documentation/trace/postprocess/trace-pagealloc-postprocess.pl new file mode 100644 index 000000000..d16494c5e --- /dev/null +++ b/Documentation/trace/postprocess/trace-pagealloc-postprocess.pl @@ -0,0 +1,418 @@ +#!/usr/bin/env perl +# This is a POC (proof of concept or piece of crap, take your pick) for reading the +# text representation of trace output related to page allocation. It makes an attempt +# to extract some high-level information on what is going on. The accuracy of the parser +# may vary considerably +# +# Example usage: trace-pagealloc-postprocess.pl < /sys/kernel/tracing/trace_pipe +# other options +# --prepend-parent Report on the parent proc and PID +# --read-procstat If the trace lacks process info, get it from /proc +# --ignore-pid Aggregate processes of the same name together +# +# Copyright (c) IBM Corporation 2009 +# Author: Mel Gorman +use strict; +use Getopt::Long; + +# Tracepoint events +use constant MM_PAGE_ALLOC => 1; +use constant MM_PAGE_FREE => 2; +use constant MM_PAGE_FREE_BATCHED => 3; +use constant MM_PAGE_PCPU_DRAIN => 4; +use constant MM_PAGE_ALLOC_ZONE_LOCKED => 5; +use constant MM_PAGE_ALLOC_EXTFRAG => 6; +use constant EVENT_UNKNOWN => 7; + +# Constants used to track state +use constant STATE_PCPU_PAGES_DRAINED => 8; +use constant STATE_PCPU_PAGES_REFILLED => 9; + +# High-level events extrapolated from tracepoints +use constant HIGH_PCPU_DRAINS => 10; +use constant HIGH_PCPU_REFILLS => 11; +use constant HIGH_EXT_FRAGMENT => 12; +use constant HIGH_EXT_FRAGMENT_SEVERE => 13; +use constant HIGH_EXT_FRAGMENT_MODERATE => 14; +use constant HIGH_EXT_FRAGMENT_CHANGED => 15; + +my %perprocesspid; +my %perprocess; +my $opt_ignorepid; +my $opt_read_procstat; +my $opt_prepend_parent; + +# Catch sigint and exit on request +my $sigint_report = 0; +my $sigint_exit = 0; +my $sigint_pending = 0; +my $sigint_received = 0; +sub sigint_handler { + my $current_time = time; + if ($current_time - 2 > $sigint_received) { + print "SIGINT received, report pending. Hit ctrl-c again to exit\n"; + $sigint_report = 1; + } else { + if (!$sigint_exit) { + print "Second SIGINT received quickly, exiting\n"; + } + $sigint_exit++; + } + + if ($sigint_exit > 3) { + print "Many SIGINTs received, exiting now without report\n"; + exit; + } + + $sigint_received = $current_time; + $sigint_pending = 1; +} +$SIG{INT} = "sigint_handler"; + +# Parse command line options +GetOptions( + 'ignore-pid' => \$opt_ignorepid, + 'read-procstat' => \$opt_read_procstat, + 'prepend-parent' => \$opt_prepend_parent, +); + +# Defaults for dynamically discovered regex's +my $regex_fragdetails_default = 'page=([0-9a-f]*) pfn=([0-9]*) alloc_order=([-0-9]*) fallback_order=([-0-9]*) pageblock_order=([-0-9]*) alloc_migratetype=([-0-9]*) fallback_migratetype=([-0-9]*) fragmenting=([-0-9]) change_ownership=([-0-9])'; + +# Dyanically discovered regex +my $regex_fragdetails; + +# Static regex used. Specified like this for readability and for use with /o +# (process_pid) (cpus ) ( time ) (tpoint ) (details) +my $regex_traceevent = '\s*([a-zA-Z0-9-]*)\s*(\[[0-9]*\])\s*([0-9.]*):\s*([a-zA-Z_]*):\s*(.*)'; +my $regex_statname = '[-0-9]*\s\((.*)\).*'; +my $regex_statppid = '[-0-9]*\s\(.*\)\s[A-Za-z]\s([0-9]*).*'; + +sub generate_traceevent_regex { + my $event = shift; + my $default = shift; + my $regex; + + # Read the event format or use the default + if (!open (FORMAT, "/sys/kernel/tracing/events/$event/format")) { + $regex = $default; + } else { + my $line; + while (!eof(FORMAT)) { + $line = ; + if ($line =~ /^print fmt:\s"(.*)",.*/) { + $regex = $1; + $regex =~ s/%p/\([0-9a-f]*\)/g; + $regex =~ s/%d/\([-0-9]*\)/g; + $regex =~ s/%lu/\([0-9]*\)/g; + } + } + } + + # Verify fields are in the right order + my $tuple; + foreach $tuple (split /\s/, $regex) { + my ($key, $value) = split(/=/, $tuple); + my $expected = shift; + if ($key ne $expected) { + print("WARNING: Format not as expected '$key' != '$expected'"); + $regex =~ s/$key=\((.*)\)/$key=$1/; + } + } + + if (defined shift) { + die("Fewer fields than expected in format"); + } + + return $regex; +} +$regex_fragdetails = generate_traceevent_regex("kmem/mm_page_alloc_extfrag", + $regex_fragdetails_default, + "page", "pfn", + "alloc_order", "fallback_order", "pageblock_order", + "alloc_migratetype", "fallback_migratetype", + "fragmenting", "change_ownership"); + +sub read_statline($) { + my $pid = $_[0]; + my $statline; + + if (open(STAT, "/proc/$pid/stat")) { + $statline = ; + close(STAT); + } + + if ($statline eq '') { + $statline = "-1 (UNKNOWN_PROCESS_NAME) R 0"; + } + + return $statline; +} + +sub guess_process_pid($$) { + my $pid = $_[0]; + my $statline = $_[1]; + + if ($pid == 0) { + return "swapper-0"; + } + + if ($statline !~ /$regex_statname/o) { + die("Failed to math stat line for process name :: $statline"); + } + return "$1-$pid"; +} + +sub parent_info($$) { + my $pid = $_[0]; + my $statline = $_[1]; + my $ppid; + + if ($pid == 0) { + return "NOPARENT-0"; + } + + if ($statline !~ /$regex_statppid/o) { + die("Failed to match stat line process ppid:: $statline"); + } + + # Read the ppid stat line + $ppid = $1; + return guess_process_pid($ppid, read_statline($ppid)); +} + +sub process_events { + my $traceevent; + my $process_pid; + my $cpus; + my $timestamp; + my $tracepoint; + my $details; + my $statline; + + # Read each line of the event log +EVENT_PROCESS: + while ($traceevent = ) { + if ($traceevent =~ /$regex_traceevent/o) { + $process_pid = $1; + $tracepoint = $4; + + if ($opt_read_procstat || $opt_prepend_parent) { + $process_pid =~ /(.*)-([0-9]*)$/; + my $process = $1; + my $pid = $2; + + $statline = read_statline($pid); + + if ($opt_read_procstat && $process eq '') { + $process_pid = guess_process_pid($pid, $statline); + } + + if ($opt_prepend_parent) { + $process_pid = parent_info($pid, $statline) . " :: $process_pid"; + } + } + + # Unnecessary in this script. Uncomment if required + # $cpus = $2; + # $timestamp = $3; + } else { + next; + } + + # Perl Switch() sucks majorly + if ($tracepoint eq "mm_page_alloc") { + $perprocesspid{$process_pid}->{MM_PAGE_ALLOC}++; + } elsif ($tracepoint eq "mm_page_free") { + $perprocesspid{$process_pid}->{MM_PAGE_FREE}++ + } elsif ($tracepoint eq "mm_page_free_batched") { + $perprocesspid{$process_pid}->{MM_PAGE_FREE_BATCHED}++; + } elsif ($tracepoint eq "mm_page_pcpu_drain") { + $perprocesspid{$process_pid}->{MM_PAGE_PCPU_DRAIN}++; + $perprocesspid{$process_pid}->{STATE_PCPU_PAGES_DRAINED}++; + } elsif ($tracepoint eq "mm_page_alloc_zone_locked") { + $perprocesspid{$process_pid}->{MM_PAGE_ALLOC_ZONE_LOCKED}++; + $perprocesspid{$process_pid}->{STATE_PCPU_PAGES_REFILLED}++; + } elsif ($tracepoint eq "mm_page_alloc_extfrag") { + + # Extract the details of the event now + $details = $5; + + my ($page, $pfn); + my ($alloc_order, $fallback_order, $pageblock_order); + my ($alloc_migratetype, $fallback_migratetype); + my ($fragmenting, $change_ownership); + + if ($details !~ /$regex_fragdetails/o) { + print "WARNING: Failed to parse mm_page_alloc_extfrag as expected\n"; + next; + } + + $perprocesspid{$process_pid}->{MM_PAGE_ALLOC_EXTFRAG}++; + $page = $1; + $pfn = $2; + $alloc_order = $3; + $fallback_order = $4; + $pageblock_order = $5; + $alloc_migratetype = $6; + $fallback_migratetype = $7; + $fragmenting = $8; + $change_ownership = $9; + + if ($fragmenting) { + $perprocesspid{$process_pid}->{HIGH_EXT_FRAG}++; + if ($fallback_order <= 3) { + $perprocesspid{$process_pid}->{HIGH_EXT_FRAGMENT_SEVERE}++; + } else { + $perprocesspid{$process_pid}->{HIGH_EXT_FRAGMENT_MODERATE}++; + } + } + if ($change_ownership) { + $perprocesspid{$process_pid}->{HIGH_EXT_FRAGMENT_CHANGED}++; + } + } else { + $perprocesspid{$process_pid}->{EVENT_UNKNOWN}++; + } + + # Catch a full pcpu drain event + if ($perprocesspid{$process_pid}->{STATE_PCPU_PAGES_DRAINED} && + $tracepoint ne "mm_page_pcpu_drain") { + + $perprocesspid{$process_pid}->{HIGH_PCPU_DRAINS}++; + $perprocesspid{$process_pid}->{STATE_PCPU_PAGES_DRAINED} = 0; + } + + # Catch a full pcpu refill event + if ($perprocesspid{$process_pid}->{STATE_PCPU_PAGES_REFILLED} && + $tracepoint ne "mm_page_alloc_zone_locked") { + $perprocesspid{$process_pid}->{HIGH_PCPU_REFILLS}++; + $perprocesspid{$process_pid}->{STATE_PCPU_PAGES_REFILLED} = 0; + } + + if ($sigint_pending) { + last EVENT_PROCESS; + } + } +} + +sub dump_stats { + my $hashref = shift; + my %stats = %$hashref; + + # Dump per-process stats + my $process_pid; + my $max_strlen = 0; + + # Get the maximum process name + foreach $process_pid (keys %perprocesspid) { + my $len = length($process_pid); + if ($len > $max_strlen) { + $max_strlen = $len; + } + } + $max_strlen += 2; + + printf("\n"); + printf("%-" . $max_strlen . "s %8s %10s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s\n", + "Process", "Pages", "Pages", "Pages", "Pages", "PCPU", "PCPU", "PCPU", "Fragment", "Fragment", "MigType", "Fragment", "Fragment", "Unknown"); + printf("%-" . $max_strlen . "s %8s %10s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s\n", + "details", "allocd", "allocd", "freed", "freed", "pages", "drains", "refills", "Fallback", "Causing", "Changed", "Severe", "Moderate", ""); + + printf("%-" . $max_strlen . "s %8s %10s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s %8s\n", + "", "", "under lock", "direct", "pagevec", "drain", "", "", "", "", "", "", "", ""); + + foreach $process_pid (keys %stats) { + # Dump final aggregates + if ($stats{$process_pid}->{STATE_PCPU_PAGES_DRAINED}) { + $stats{$process_pid}->{HIGH_PCPU_DRAINS}++; + $stats{$process_pid}->{STATE_PCPU_PAGES_DRAINED} = 0; + } + if ($stats{$process_pid}->{STATE_PCPU_PAGES_REFILLED}) { + $stats{$process_pid}->{HIGH_PCPU_REFILLS}++; + $stats{$process_pid}->{STATE_PCPU_PAGES_REFILLED} = 0; + } + + printf("%-" . $max_strlen . "s %8d %10d %8d %8d %8d %8d %8d %8d %8d %8d %8d %8d %8d\n", + $process_pid, + $stats{$process_pid}->{MM_PAGE_ALLOC}, + $stats{$process_pid}->{MM_PAGE_ALLOC_ZONE_LOCKED}, + $stats{$process_pid}->{MM_PAGE_FREE}, + $stats{$process_pid}->{MM_PAGE_FREE_BATCHED}, + $stats{$process_pid}->{MM_PAGE_PCPU_DRAIN}, + $stats{$process_pid}->{HIGH_PCPU_DRAINS}, + $stats{$process_pid}->{HIGH_PCPU_REFILLS}, + $stats{$process_pid}->{MM_PAGE_ALLOC_EXTFRAG}, + $stats{$process_pid}->{HIGH_EXT_FRAG}, + $stats{$process_pid}->{HIGH_EXT_FRAGMENT_CHANGED}, + $stats{$process_pid}->{HIGH_EXT_FRAGMENT_SEVERE}, + $stats{$process_pid}->{HIGH_EXT_FRAGMENT_MODERATE}, + $stats{$process_pid}->{EVENT_UNKNOWN}); + } +} + +sub aggregate_perprocesspid() { + my $process_pid; + my $process; + undef %perprocess; + + foreach $process_pid (keys %perprocesspid) { + $process = $process_pid; + $process =~ s/-([0-9])*$//; + if ($process eq '') { + $process = "NO_PROCESS_NAME"; + } + + $perprocess{$process}->{MM_PAGE_ALLOC} += $perprocesspid{$process_pid}->{MM_PAGE_ALLOC}; + $perprocess{$process}->{MM_PAGE_ALLOC_ZONE_LOCKED} += $perprocesspid{$process_pid}->{MM_PAGE_ALLOC_ZONE_LOCKED}; + $perprocess{$process}->{MM_PAGE_FREE} += $perprocesspid{$process_pid}->{MM_PAGE_FREE}; + $perprocess{$process}->{MM_PAGE_FREE_BATCHED} += $perprocesspid{$process_pid}->{MM_PAGE_FREE_BATCHED}; + $perprocess{$process}->{MM_PAGE_PCPU_DRAIN} += $perprocesspid{$process_pid}->{MM_PAGE_PCPU_DRAIN}; + $perprocess{$process}->{HIGH_PCPU_DRAINS} += $perprocesspid{$process_pid}->{HIGH_PCPU_DRAINS}; + $perprocess{$process}->{HIGH_PCPU_REFILLS} += $perprocesspid{$process_pid}->{HIGH_PCPU_REFILLS}; + $perprocess{$process}->{MM_PAGE_ALLOC_EXTFRAG} += $perprocesspid{$process_pid}->{MM_PAGE_ALLOC_EXTFRAG}; + $perprocess{$process}->{HIGH_EXT_FRAG} += $perprocesspid{$process_pid}->{HIGH_EXT_FRAG}; + $perprocess{$process}->{HIGH_EXT_FRAGMENT_CHANGED} += $perprocesspid{$process_pid}->{HIGH_EXT_FRAGMENT_CHANGED}; + $perprocess{$process}->{HIGH_EXT_FRAGMENT_SEVERE} += $perprocesspid{$process_pid}->{HIGH_EXT_FRAGMENT_SEVERE}; + $perprocess{$process}->{HIGH_EXT_FRAGMENT_MODERATE} += $perprocesspid{$process_pid}->{HIGH_EXT_FRAGMENT_MODERATE}; + $perprocess{$process}->{EVENT_UNKNOWN} += $perprocesspid{$process_pid}->{EVENT_UNKNOWN}; + } +} + +sub report() { + if (!$opt_ignorepid) { + dump_stats(\%perprocesspid); + } else { + aggregate_perprocesspid(); + dump_stats(\%perprocess); + } +} + +# Process events or signals until neither is available +sub signal_loop() { + my $sigint_processed; + do { + $sigint_processed = 0; + process_events(); + + # Handle pending signals if any + if ($sigint_pending) { + my $current_time = time; + + if ($sigint_exit) { + print "Received exit signal\n"; + $sigint_pending = 0; + } + if ($sigint_report) { + if ($current_time >= $sigint_received + 2) { + report(); + $sigint_report = 0; + $sigint_pending = 0; + $sigint_processed = 1; + } + } + } + } while ($sigint_pending || $sigint_processed); +} + +signal_loop(); +report(); -- cgit v1.3.1