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/macro_checker.py | 131 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 131 insertions(+) create mode 100755 scripts/macro_checker.py (limited to 'scripts/macro_checker.py') diff --git a/scripts/macro_checker.py b/scripts/macro_checker.py new file mode 100755 index 000000000..ba550982e --- /dev/null +++ b/scripts/macro_checker.py @@ -0,0 +1,131 @@ +#!/usr/bin/python3 +# SPDX-License-Identifier: GPL-2.0 +# Author: Julian Sun + +""" Find macro definitions with unused parameters. """ + +import argparse +import os +import re + +parser = argparse.ArgumentParser() + +parser.add_argument("path", type=str, help="The file or dir path that needs check") +parser.add_argument("-v", "--verbose", action="store_true", + help="Check conditional macros, but may lead to more false positives") +args = parser.parse_args() + +macro_pattern = r"#define\s+(\w+)\(([^)]*)\)" +# below vars were used to reduce false positives +fp_patterns = [r"\s*do\s*\{\s*\}\s*while\s*\(\s*0\s*\)", + r"\(?0\)?", r"\(?1\)?"] +correct_macros = [] +cond_compile_mark = "#if" +cond_compile_end = "#endif" + +def check_macro(macro_line, report): + match = re.match(macro_pattern, macro_line) + if match: + macro_def = re.sub(macro_pattern, '', macro_line) + identifier = match.group(1) + content = match.group(2) + arguments = [item.strip() for item in content.split(',') if item.strip()] + + macro_def = macro_def.strip() + if not macro_def: + return + # used to reduce false positives, like #define endfor_nexthops(rt) } + if len(macro_def) == 1: + return + + for fp_pattern in fp_patterns: + if (re.match(fp_pattern, macro_def)): + return + + for arg in arguments: + # used to reduce false positives + if "..." in arg: + return + for arg in arguments: + if not arg in macro_def and report == False: + return + # if there is a correct macro with the same name, do not report it. + if not arg in macro_def and identifier not in correct_macros: + print(f"Argument {arg} is not used in function-line macro {identifier}") + return + + correct_macros.append(identifier) + + +# remove comment and whitespace +def macro_strip(macro): + comment_pattern1 = r"\/\/*" + comment_pattern2 = r"\/\**\*\/" + + macro = macro.strip() + macro = re.sub(comment_pattern1, '', macro) + macro = re.sub(comment_pattern2, '', macro) + + return macro + +def file_check_macro(file_path, report): + # number of conditional compiling + cond_compile = 0 + # only check .c and .h file + if not file_path.endswith(".c") and not file_path.endswith(".h"): + return + + with open(file_path, "r") as f: + while True: + line = f.readline() + if not line: + break + line = line.strip() + if line.startswith(cond_compile_mark): + cond_compile += 1 + continue + if line.startswith(cond_compile_end): + cond_compile -= 1 + continue + + macro = re.match(macro_pattern, line) + if macro: + macro = macro_strip(macro.string) + while macro[-1] == '\\': + macro = macro[0:-1] + macro = macro.strip() + macro += f.readline() + macro = macro_strip(macro) + if not args.verbose: + if file_path.endswith(".c") and cond_compile != 0: + continue + # 1 is for #ifdef xxx at the beginning of the header file + if file_path.endswith(".h") and cond_compile != 1: + continue + check_macro(macro, report) + +def get_correct_macros(path): + file_check_macro(path, False) + +def dir_check_macro(dir_path): + + for dentry in os.listdir(dir_path): + path = os.path.join(dir_path, dentry) + if os.path.isdir(path): + dir_check_macro(path) + elif os.path.isfile(path): + get_correct_macros(path) + file_check_macro(path, True) + + +def main(): + if os.path.isfile(args.path): + get_correct_macros(args.path) + file_check_macro(args.path, True) + elif os.path.isdir(args.path): + dir_check_macro(args.path) + else: + print(f"{args.path} doesn't exit or is neither a file nor a dir") + +if __name__ == "__main__": + main() \ No newline at end of file -- cgit v1.3.1