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 --- tools/writeback/wb_monitor.py | 172 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 172 insertions(+) create mode 100644 tools/writeback/wb_monitor.py (limited to 'tools/writeback') diff --git a/tools/writeback/wb_monitor.py b/tools/writeback/wb_monitor.py new file mode 100644 index 000000000..5e3591f1f --- /dev/null +++ b/tools/writeback/wb_monitor.py @@ -0,0 +1,172 @@ +#!/usr/bin/env drgn +# +# Copyright (C) 2024 Kemeng Shi +# Copyright (C) 2024 Huawei Inc + +desc = """ +This is a drgn script based on wq_monitor.py to monitor writeback info on +backing dev. For more info on drgn, visit https://github.com/osandov/drgn. + + writeback(kB) Amount of dirty pages are currently being written back to + disk. + + reclaimable(kB) Amount of pages are currently reclaimable. + + dirtied(kB) Amount of pages have been dirtied. + + wrttien(kB) Amount of dirty pages have been written back to disk. + + avg_wb(kBps) Smoothly estimated write bandwidth of writing dirty pages + back to disk. +""" + +import signal +import re +import time +import json + +import drgn +from drgn.helpers.linux.list import list_for_each_entry + +import argparse +parser = argparse.ArgumentParser(description=desc, + formatter_class=argparse.RawTextHelpFormatter) +parser.add_argument('bdi', metavar='REGEX', nargs='*', + help='Target backing device name patterns (all if empty)') +parser.add_argument('-i', '--interval', metavar='SECS', type=float, default=1, + help='Monitoring interval (0 to print once and exit)') +parser.add_argument('-j', '--json', action='store_true', + help='Output in json') +parser.add_argument('-c', '--cgroup', action='store_true', + help='show writeback of bdi in cgroup') +args = parser.parse_args() + +bdi_list = prog['bdi_list'] + +WB_RECLAIMABLE = prog['WB_RECLAIMABLE'] +WB_WRITEBACK = prog['WB_WRITEBACK'] +WB_DIRTIED = prog['WB_DIRTIED'] +WB_WRITTEN = prog['WB_WRITTEN'] +NR_WB_STAT_ITEMS = prog['NR_WB_STAT_ITEMS'] + +PAGE_SHIFT = prog['PAGE_SHIFT'] + +def K(x): + return x << (PAGE_SHIFT - 10) + +class Stats: + def dict(self, now): + return { 'timestamp' : now, + 'name' : self.name, + 'writeback' : self.stats[WB_WRITEBACK], + 'reclaimable' : self.stats[WB_RECLAIMABLE], + 'dirtied' : self.stats[WB_DIRTIED], + 'written' : self.stats[WB_WRITTEN], + 'avg_wb' : self.avg_bw, } + + def table_header_str(): + return f'{"":>16} {"writeback":>10} {"reclaimable":>12} ' \ + f'{"dirtied":>9} {"written":>9} {"avg_bw":>9}' + + def table_row_str(self): + out = f'{self.name[-16:]:16} ' \ + f'{self.stats[WB_WRITEBACK]:10} ' \ + f'{self.stats[WB_RECLAIMABLE]:12} ' \ + f'{self.stats[WB_DIRTIED]:9} ' \ + f'{self.stats[WB_WRITTEN]:9} ' \ + f'{self.avg_bw:9} ' + return out + + def show_header(): + if Stats.table_fmt: + print() + print(Stats.table_header_str()) + + def show_stats(self): + if Stats.table_fmt: + print(self.table_row_str()) + else: + print(self.dict(Stats.now)) + +class WbStats(Stats): + def __init__(self, wb): + bdi_name = wb.bdi.dev_name.string_().decode() + # avoid to use bdi.wb.memcg_css which is only defined when + # CONFIG_CGROUP_WRITEBACK is enabled + if wb == wb.bdi.wb.address_of_(): + ino = "1" + else: + ino = str(wb.memcg_css.cgroup.kn.id.value_()) + self.name = bdi_name + '_' + ino + + self.stats = [0] * NR_WB_STAT_ITEMS + for i in range(NR_WB_STAT_ITEMS): + if wb.stat[i].count >= 0: + self.stats[i] = int(K(wb.stat[i].count)) + else: + self.stats[i] = 0 + + self.avg_bw = int(K(wb.avg_write_bandwidth)) + +class BdiStats(Stats): + def __init__(self, bdi): + self.name = bdi.dev_name.string_().decode() + self.stats = [0] * NR_WB_STAT_ITEMS + self.avg_bw = 0 + + def collectStats(self, wb_stats): + for i in range(NR_WB_STAT_ITEMS): + self.stats[i] += wb_stats.stats[i] + + self.avg_bw += wb_stats.avg_bw + +exit_req = False + +def sigint_handler(signr, frame): + global exit_req + exit_req = True + +def main(): + # handle args + Stats.table_fmt = not args.json + interval = args.interval + cgroup = args.cgroup + + re_str = None + if args.bdi: + for r in args.bdi: + if re_str is None: + re_str = r + else: + re_str += '|' + r + + filter_re = re.compile(re_str) if re_str else None + + # monitoring loop + signal.signal(signal.SIGINT, sigint_handler) + + while not exit_req: + Stats.now = time.time() + + Stats.show_header() + for bdi in list_for_each_entry('struct backing_dev_info', bdi_list.address_of_(), 'bdi_list'): + bdi_stats = BdiStats(bdi) + if filter_re and not filter_re.search(bdi_stats.name): + continue + + for wb in list_for_each_entry('struct bdi_writeback', bdi.wb_list.address_of_(), 'bdi_node'): + wb_stats = WbStats(wb) + bdi_stats.collectStats(wb_stats) + if cgroup: + wb_stats.show_stats() + + bdi_stats.show_stats() + if cgroup and Stats.table_fmt: + print() + + if interval == 0: + break + time.sleep(interval) + +if __name__ == "__main__": + main() -- cgit v1.3.1