On Wed, Feb 28, 2024 at 8:41 AM Vlastimil Babka [off-list ref] wrote:

Another thing I noticed, dunno how critical

On 2/21/24 20:40, Suren Baghdasaryan wrote:

quoted

+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.

quoted

+
+     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.

quoted

+
+     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

quoted

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

But here we still assume it's valid.

Yes, this is a blunder on my side after splitting alloc_tag_ref_set()
into a separate function. I'll fix this in the next version. Thanks!

quoted

+}
+

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