From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- tools/cgroup/memcg_shrinker.py | 70 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) create mode 100644 tools/cgroup/memcg_shrinker.py (limited to 'tools/cgroup/memcg_shrinker.py') diff --git a/tools/cgroup/memcg_shrinker.py b/tools/cgroup/memcg_shrinker.py new file mode 100644 index 000000000..e81c3017a --- /dev/null +++ b/tools/cgroup/memcg_shrinker.py @@ -0,0 +1,70 @@ +#!/usr/bin/env python3 +# +# Copyright (C) 2022 Roman Gushchin +# Copyright (C) 2022 Meta + +import os +import argparse + + +def scan_cgroups(cgroup_root): + cgroups = {} + + for root, subdirs, _ in os.walk(cgroup_root): + for cgroup in subdirs: + path = os.path.join(root, cgroup) + ino = os.stat(path).st_ino + cgroups[ino] = path + + # (memcg ino, path) + return cgroups + + +def scan_shrinkers(shrinker_debugfs): + shrinkers = [] + + for root, subdirs, _ in os.walk(shrinker_debugfs): + for shrinker in subdirs: + count_path = os.path.join(root, shrinker, "count") + with open(count_path) as f: + for line in f.readlines(): + items = line.split(' ') + ino = int(items[0]) + # (count, shrinker, memcg ino) + shrinkers.append((int(items[1]), shrinker, ino)) + return shrinkers + + +def main(): + parser = argparse.ArgumentParser(description='Display biggest shrinkers') + parser.add_argument('-n', '--lines', type=int, help='Number of lines to print') + + args = parser.parse_args() + + cgroups = scan_cgroups("/sys/fs/cgroup/") + shrinkers = scan_shrinkers("/sys/kernel/debug/shrinker/") + shrinkers.sort(reverse = True, key = lambda x: x[0]) + + n = 0 + for s in shrinkers: + count, name, ino = (s[0], s[1], s[2]) + if count == 0: + break + + if ino == 0 or ino == 1: + cg = "/" + else: + try: + cg = cgroups[ino] + except KeyError: + cg = "unknown (%d)" % ino + + print("%-8s %-20s %s" % (count, name, cg)) + + n += 1 + if args.lines and n >= args.lines: + break + + +if __name__ == '__main__': + main() -- cgit v1.3.1