Re: [RFC PATCH bpf-next v3 08/12] mm: memcontrol: Add BPF struct_ops for memory controller
From: bot+bpf-ci@kernel.org
Date: 2026-01-23 09:29:47
Also in:
bpf, cgroups, linux-kselftest, linux-mm, lkml
quoted hunk ↗ jump to hunk
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index f3b8c71870d8..d71e86b85ba7 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h
[ ... ]
+#else /* CONFIG_BPF_SYSCALL */
+
+static inline unsigned long
+bpf_memcg_get_high_delay(struct mem_cgroup *memcg) { return 0 }
+static inline bpf_memcg_below_low(struct mem_cgroup *memcg) { return false }
+static inline bpf_memcg_below_min(struct mem_cgroup *memcg) { return false } ^^^^^^^^^^^^^^^^^^^^
These stub functions appear to have syntax issues that would prevent
compilation when CONFIG_BPF_SYSCALL is disabled:
1. bpf_memcg_get_high_delay() is missing a semicolon after "return 0"
2. bpf_memcg_below_low() is missing the "bool" return type
3. bpf_memcg_below_min() is missing the "bool" return type
Should these be:
static inline unsigned long
bpf_memcg_get_high_delay(struct mem_cgroup *memcg) { return 0; }
static inline bool bpf_memcg_below_low(struct mem_cgroup *memcg) { return false; }
static inline bool bpf_memcg_below_min(struct mem_cgroup *memcg) { return false; }
+static inline void memcontrol_bpf_online(struct mem_cgroup *memcg) { }
+static inline void memcontrol_bpf_offline(struct mem_cgroup *memcg) { }
+
+#endif /* CONFIG_BPF_SYSCALL */[ ... ]
quoted hunk ↗ jump to hunk
diff --git a/mm/bpf_memcontrol.c b/mm/bpf_memcontrol.c index 716df49d7647..415e3c59b6a6 100644 --- a/mm/bpf_memcontrol.c +++ b/mm/bpf_memcontrol.c
[ ... ]
+static void clean_memcg_bpf_ops(struct mem_cgroup *memcg,
+ struct memcg_bpf_ops *ops)
+{
+ struct mem_cgroup *iter = NULL;
+
+ while ((iter = mem_cgroup_iter(memcg, iter, NULL))) {
+ if (ops) {
+ if (!WARN_ON(READ_ONCE(memcg->bpf_ops) != ops))
+ WRITE_ONCE(memcg->bpf_ops, NULL);^^^^^ When ops is non-NULL, this code checks and writes to memcg->bpf_ops, but should it be using iter->bpf_ops instead? The else branch at the bottom correctly uses iter. As written, when called from bpf_memcg_ops_unreg() with a non-NULL ops argument, this only clears the root cgroup's bpf_ops pointer while leaving all descendant cgroups with stale pointers to the ops structure that will be freed after synchronize_srcu().
+ } else + WRITE_ONCE(iter->bpf_ops, NULL); + } +}
[ ... ]
+static int __init bpf_memcontrol_init(void)
+{
+ int err, err2;
+
+ err = register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC,
+ &bpf_memcontrol_kfunc_set);
+ if (err)
+ pr_warn("error while registering bpf memcontrol kfuncs: %d", err);
+
+ err2 = register_bpf_struct_ops(&bpf_memcg_bpf_ops, memcg_bpf_ops);
+ if (err)^^^ The condition here checks err but prints err2. Should this be "if (err2)" to log when the struct_ops registration fails?
+ pr_warn("error while registering memcontrol bpf ops: %d", err2);
+
+ return err ? err : err2;
+}
+late_initcall(bpf_memcontrol_init);Note: The clean_memcg_bpf_ops() issue appears to be addressed in a later commit in this series (90eaa9cd0346 "mm/bpf: Add BPF_F_ALLOW_OVERRIDE support for memcg_bpf_ops") which removes and rewrites the function entirely. However, the syntax errors in the stubs and the error check typo in bpf_memcontrol_init() do not appear to be fixed in the series. --- AI reviewed your patch. Please fix the bug or email reply why it's not a bug. See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21280790825