lib: introduce support for page allocation tagging

Introduce helper functions to easily instrument page allocators by storing
a pointer to the allocation tag associated with the code that allocated
the page in a page_ext field.

Link: https://lkml.kernel.org/r/20240321163705.3067592-15-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Co-developed-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 78 insertions, 1 deletions

diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index be98564191e6..07e0656898f9 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -4,7 +4,6 @@
 
 #include <linux/types.h>
 #include <linux/stacktrace.h>
-#include <linux/stackdepot.h>
 
 struct pglist_data;
 
diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h
new file mode 100644
index 000000000000..66bd021eb46e
--- /dev/null
+++ b/include/linux/pgalloc_tag.h
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * page allocation tagging
+ */
+#ifndef _LINUX_PGALLOC_TAG_H
+#define _LINUX_PGALLOC_TAG_H
+
+#include <linux/alloc_tag.h>
+
+#ifdef CONFIG_MEM_ALLOC_PROFILING
+
+#include <linux/page_ext.h>
+
+extern struct page_ext_operations page_alloc_tagging_ops;
+extern struct page_ext *page_ext_get(struct page *page);
+extern void page_ext_put(struct page_ext *page_ext);
+
+static inline union codetag_ref *codetag_ref_from_page_ext(struct page_ext *page_ext)
+{
+	return (void *)page_ext + page_alloc_tagging_ops.offset;
+}
+
+static inline struct page_ext *page_ext_from_codetag_ref(union codetag_ref *ref)
+{
+	return (void *)ref - page_alloc_tagging_ops.offset;
+}
+
+/* Should be called only if mem_alloc_profiling_enabled() */
+static inline union codetag_ref *get_page_tag_ref(struct page *page)
+{
+	if (page) {
+		struct page_ext *page_ext = page_ext_get(page);
+
+		if (page_ext)
+			return codetag_ref_from_page_ext(page_ext);
+	}
+	return NULL;
+}
+
+static inline void put_page_tag_ref(union codetag_ref *ref)
+{
+	page_ext_put(page_ext_from_codetag_ref(ref));
+}
+
+static inline void pgalloc_tag_add(struct page *page, struct task_struct *task,
+				   unsigned int nr)
+{
+	if (mem_alloc_profiling_enabled()) {
+		union codetag_ref *ref = get_page_tag_ref(page);
+
+		if (ref) {
+			alloc_tag_add(ref, task->alloc_tag, PAGE_SIZE * nr);
+			put_page_tag_ref(ref);
+		}
+	}
+}
+
+static inline void pgalloc_tag_sub(struct page *page, unsigned int nr)
+{
+	if (mem_alloc_profiling_enabled()) {
+		union codetag_ref *ref = get_page_tag_ref(page);
+
+		if (ref) {
+			alloc_tag_sub(ref, PAGE_SIZE * nr);
+			put_page_tag_ref(ref);
+		}
+	}
+}
+
+#else /* CONFIG_MEM_ALLOC_PROFILING */
+
+static inline void pgalloc_tag_add(struct page *page, struct task_struct *task,
+				   unsigned int nr) {}
+static inline void pgalloc_tag_sub(struct page *page, unsigned int nr) {}
+
+#endif /* CONFIG_MEM_ALLOC_PROFILING */
+
+#endif /* _LINUX_PGALLOC_TAG_H */