Re: [PATCH v4 14/36] lib: add allocation tagging support for memory allocation profiling

Vlastimil Babka
2024-02-28T08:41:25Z

Another thing I noticed, dunno how critical

On 2/21/24 20:40, Suren Baghdasaryan wrote:
> +static inline void __alloc_tag_sub(union codetag_ref *ref, size_t bytes)
> +{
> + struct alloc_tag *tag;
> +
> +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
> + WARN_ONCE(ref && !ref->ct, "alloc_tag was not set\n");
> +#endif
> + if (!ref || !ref->ct)
> + return;

This is quite careful.

> +
> + tag = ct_to_alloc_tag(ref->ct);
> +
> + this_cpu_sub(tag->counters->bytes, bytes);
> + this_cpu_dec(tag->counters->calls);
> +
> + ref->ct = NULL;
> +}
> +
> +static inline void alloc_tag_sub(union codetag_ref *ref, size_t bytes)
> +{
> + __alloc_tag_sub(ref, bytes);
> +}
> +
> +static inline void alloc_tag_sub_noalloc(union codetag_ref *ref, size_t bytes)
> +{
> + __alloc_tag_sub(ref, bytes);
> +}
> +
> +static inline void alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag *tag)
> +{
> +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
> + WARN_ONCE(ref && ref->ct,
> + "alloc_tag was not cleared (got tag for %s:%u)\n",\
> + ref->ct->filename, ref->ct->lineno);
> +
> + WARN_ONCE(!tag, "current->alloc_tag not set");
> +#endif
> + if (!ref || !tag)
> + return;

This too.

> +
> + ref->ct = &tag->ct;
> + /*
> + * We need in increment the call counter every time we have a new
> + * allocation or when we split a large allocation into smaller ones.
> + * Each new reference for every sub-allocation needs to increment call
> + * counter because when we free each part the counter will be decremented.
> + */
> + this_cpu_inc(tag->counters->calls);
> +}
> +
> +static inline void alloc_tag_add(union codetag_ref *ref, struct alloc_tag *tag, size_t bytes)
> +{
> + alloc_tag_ref_set(ref, tag);

We might have returned from alloc_tag_ref_set() due to !tag

> + this_cpu_add(tag->counters->bytes, bytes);

But here we still assume it's valid.

> +}
> +