[PATCH v2 4/6] alloc_tag: introduce pgalloc_tag_ref to abstract page tag references

Suren Baghdasaryan
2024-09-02T04:41:41Z

To simplify later changes to page tag references, introduce new
pgalloc_tag_ref and pgtag_ref_handle types. This allows easy
replacement of page_ext as a storage of page allocation tags

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
include/linux/pgalloc_tag.h | 144 +++++++++++++++++++++++-------------
lib/alloc_tag.c | 3 +-
2 files changed, 95 insertions(+), 52 deletions(-)

diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h
index 244a328dff62..c76b629d0206 100644
--- a/include/linux/pgalloc_tag.h
+++ b/include/linux/pgalloc_tag.h
@@ -9,48 +9,76 @@

#ifdef CONFIG_MEM_ALLOC_PROFILING

+typedef union codetag_ref pgalloc_tag_ref;
+
+static inline void read_pgref(pgalloc_tag_ref *pgref, union codetag_ref *ref)
+{
+ ref->ct = pgref->ct;
+}
+
+static inline void write_pgref(pgalloc_tag_ref *pgref, union codetag_ref *ref)
+{
+ pgref->ct = ref->ct;
+}
#include <linux/page_ext.h>

extern struct page_ext_operations page_alloc_tagging_ops;

-static inline union codetag_ref *codetag_ref_from_page_ext(struct page_ext *page_ext)
+static inline pgalloc_tag_ref *pgref_from_page_ext(struct page_ext *page_ext)
{
- return (union codetag_ref *)page_ext_data(page_ext, &page_alloc_tagging_ops);
+ return (pgalloc_tag_ref *)page_ext_data(page_ext, &page_alloc_tagging_ops);
}

-static inline struct page_ext *page_ext_from_codetag_ref(union codetag_ref *ref)
+static inline struct page_ext *page_ext_from_pgref(pgalloc_tag_ref *pgref)
{
- return (void *)ref - page_alloc_tagging_ops.offset;
+ return (void *)pgref - page_alloc_tagging_ops.offset;
}

+typedef pgalloc_tag_ref *pgtag_ref_handle;
+
/* Should be called only if mem_alloc_profiling_enabled() */
-static inline union codetag_ref *get_page_tag_ref(struct page *page)
+static inline pgtag_ref_handle get_page_tag_ref(struct page *page, union codetag_ref *ref)
{
if (page) {
struct page_ext *page_ext = page_ext_get(page);

- if (page_ext)
- return codetag_ref_from_page_ext(page_ext);
+ if (page_ext) {
+ pgalloc_tag_ref *pgref = pgref_from_page_ext(page_ext);
+
+ read_pgref(pgref, ref);
+ return pgref;
+ }
}
return NULL;
}

-static inline void put_page_tag_ref(union codetag_ref *ref)
+static inline void put_page_tag_ref(pgtag_ref_handle pgref)
{
- if (WARN_ON(!ref))
+ if (WARN_ON(!pgref))
return;

- page_ext_put(page_ext_from_codetag_ref(ref));
+ page_ext_put(page_ext_from_pgref(pgref));
+}
+
+static inline void update_page_tag_ref(pgtag_ref_handle pgref, union codetag_ref *ref)
+{
+ if (WARN_ON(!pgref || !ref))
+ return;
+
+ write_pgref(pgref, ref);
}

static inline void clear_page_tag_ref(struct page *page)
{
if (mem_alloc_profiling_enabled()) {
- union codetag_ref *ref = get_page_tag_ref(page);
-
- if (ref) {
- set_codetag_empty(ref);
- put_page_tag_ref(ref);
+ pgtag_ref_handle handle;
+ union codetag_ref ref;
+
+ handle = get_page_tag_ref(page, &ref);
+ if (handle) {
+ set_codetag_empty(&ref);
+ update_page_tag_ref(handle, &ref);
+ put_page_tag_ref(handle);
}
}
}
@@ -59,11 +87,14 @@ 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);
+ pgtag_ref_handle handle;
+ union codetag_ref ref;
+
+ handle = get_page_tag_ref(page, &ref);
+ if (handle) {
+ alloc_tag_add(&ref, task->alloc_tag, PAGE_SIZE * nr);
+ update_page_tag_ref(handle, &ref);
+ put_page_tag_ref(handle);
}
}
}
@@ -71,53 +102,58 @@ static inline void pgalloc_tag_add(struct page *page, struct task_struct *task,
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);
+ pgtag_ref_handle handle;
+ union codetag_ref ref;
+
+ handle = get_page_tag_ref(page, &ref);
+ if (handle) {
+ alloc_tag_sub(&ref, PAGE_SIZE * nr);
+ update_page_tag_ref(handle, &ref);
+ put_page_tag_ref(handle);
}
}
}

static inline void pgalloc_tag_split(struct page *page, unsigned int nr)
{
- int i;
- struct page_ext *first_page_ext;
- struct page_ext *page_ext;
- union codetag_ref *ref;
+ pgtag_ref_handle first_pgref;
+ union codetag_ref first_ref;
struct alloc_tag *tag;
+ int i;

if (!mem_alloc_profiling_enabled())
return;

- first_page_ext = page_ext = page_ext_get(page);
- if (unlikely(!page_ext))
+ first_pgref = get_page_tag_ref(page, &first_ref);
+ if (unlikely(!first_pgref))
return;

- ref = codetag_ref_from_page_ext(page_ext);
- if (!ref->ct)
+ if (!first_ref.ct)
goto out;

- tag = ct_to_alloc_tag(ref->ct);
- page_ext = page_ext_next(page_ext);
+ tag = ct_to_alloc_tag(first_ref.ct);
for (i = 1; i < nr; i++) {
- /* Set new reference to point to the original tag */
- ref = codetag_ref_from_page_ext(page_ext);
- alloc_tag_add_check(ref, tag);
- if (ref) {
- ref->ct = &tag->ct;
+ pgtag_ref_handle handle;
+ union codetag_ref ref;
+
+ page++;
+ handle = get_page_tag_ref(page, &ref);
+ if (handle) {
+ /* Set new reference to point to the original tag */
+ alloc_tag_add_check(&ref, tag);
+ ref.ct = &tag->ct;
/*
* We need in increment the call counter every time we split a
* large allocation into smaller ones because when we free each
* part the counter will be decremented.
*/
this_cpu_inc(tag->counters->calls);
+ update_page_tag_ref(handle, &ref);
+ put_page_tag_ref(handle);
}
- page_ext = page_ext_next(page_ext);
}
out:
- page_ext_put(first_page_ext);
+ put_page_tag_ref(first_pgref);
}

static inline struct alloc_tag *pgalloc_tag_get(struct page *page)
@@ -125,13 +161,15 @@ static inline struct alloc_tag *pgalloc_tag_get(struct page *page)
struct alloc_tag *tag = NULL;

if (mem_alloc_profiling_enabled()) {
- union codetag_ref *ref = get_page_tag_ref(page);
-
- alloc_tag_sub_check(ref);
- if (ref) {
- if (ref->ct)
- tag = ct_to_alloc_tag(ref->ct);
- put_page_tag_ref(ref);
+ pgtag_ref_handle handle;
+ union codetag_ref ref;
+
+ handle = get_page_tag_ref(page, &ref);
+ if (handle) {
+ alloc_tag_sub_check(&ref);
+ if (ref.ct)
+ tag = ct_to_alloc_tag(ref.ct);
+ put_page_tag_ref(handle);
}
}

@@ -146,8 +184,12 @@ static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr)

#else /* CONFIG_MEM_ALLOC_PROFILING */

-static inline union codetag_ref *get_page_tag_ref(struct page *page) { return NULL; }
-static inline void put_page_tag_ref(union codetag_ref *ref) {}
+typedef void *pgtag_ref_handle;
+
+static inline pgtag_ref_handle
+get_page_tag_ref(struct page *page, union codetag_ref *ref) { return NULL; }
+static inline void put_page_tag_ref(pgtag_ref_handle handle) {}
+static inline void update_page_tag_ref(pgtag_ref_handle handle, union codetag_ref *ref) {}
static inline void clear_page_tag_ref(struct page *page) {}
static inline void pgalloc_tag_add(struct page *page, struct task_struct *task,
unsigned int nr) {}
diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index 19ef02a18611..53bd3236d30b 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -5,6 +5,7 @@
#include <linux/gfp.h>
#include <linux/module.h>
#include <linux/page_ext.h>
+#include <linux/pgalloc_tag.h>
#include <linux/proc_fs.h>
#include <linux/seq_buf.h>
#include <linux/seq_file.h>
@@ -436,7 +437,7 @@ static __init void init_page_alloc_tagging(void)
}

struct page_ext_operations page_alloc_tagging_ops = {
- .size = sizeof(union codetag_ref),
+ .size = sizeof(pgalloc_tag_ref),
.need = need_page_alloc_tagging,
.init = init_page_alloc_tagging,
};
--
2.46.0.469.g59c65b2a67-goog