[RFC PATCH 08/30] lib: introduce page allocation tagging

Suren Baghdasaryan
2022-08-30T21:51:01Z

Introduce CONFIG_PAGE_ALLOC_TAGGING which provides helper functions to
easily instrument page allocators and adds a page_ext field to store a
pointer to the allocation tag associated with the code that allocated
the page.

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>
---
include/linux/pgalloc_tag.h | 28 ++++++++++++++++++++++++++++
lib/Kconfig.debug | 11 +++++++++++
lib/Makefile | 1 +
lib/pgalloc_tag.c | 22 ++++++++++++++++++++++
mm/page_ext.c | 6 ++++++
5 files changed, 68 insertions(+)
create mode 100644 include/linux/pgalloc_tag.h
create mode 100644 lib/pgalloc_tag.c

diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h
new file mode 100644
index 000000000000..f525abfe51d4
--- /dev/null
+++ b/include/linux/pgalloc_tag.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * page allocation tagging
+ */
+#ifndef _LINUX_PGALLOC_TAG_H
+#define _LINUX_PGALLOC_TAG_H
+
+#include <linux/alloc_tag.h>
+#include <linux/page_ext.h>
+
+extern struct page_ext_operations page_alloc_tagging_ops;
+struct page_ext *lookup_page_ext(const struct page *page);
+
+static inline union codetag_ref *get_page_tag_ref(struct page *page)
+{
+ struct page_ext *page_ext = lookup_page_ext(page);
+
+ return page_ext ? (void *)page_ext + page_alloc_tagging_ops.offset
+ : NULL;
+}
+
+static inline void pgalloc_tag_dec(struct page *page, unsigned int order)
+{
+ if (page)
+ alloc_tag_sub(get_page_tag_ref(page), PAGE_SIZE << order);
+}
+
+#endif /* _LINUX_PGALLOC_TAG_H */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 795bf6993f8a..6686648843b3 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -978,6 +978,17 @@ config ALLOC_TAGGING
select CODE_TAGGING
select LAZY_PERCPU_COUNTER

+config PAGE_ALLOC_TAGGING
+ bool "Enable page allocation tagging"
+ default n
+ select ALLOC_TAGGING
+ select PAGE_EXTENSION
+ help
+ Instrument page allocators to track allocation source code and
+ collect statistics on the number of allocations and their total size
+ initiated at that code location. The mechanism can be used to track
+ memory leaks with a low performance impact.
+
source "lib/Kconfig.kasan"
source "lib/Kconfig.kfence"

diff --git a/lib/Makefile b/lib/Makefile
index dc00533fc5c8..99f732156673 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -229,6 +229,7 @@ obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o

obj-$(CONFIG_CODE_TAGGING) += codetag.o
obj-$(CONFIG_ALLOC_TAGGING) += alloc_tag.o
+obj-$(CONFIG_PAGE_ALLOC_TAGGING) += pgalloc_tag.o

lib-$(CONFIG_GENERIC_BUG) += bug.o

diff --git a/lib/pgalloc_tag.c b/lib/pgalloc_tag.c
new file mode 100644
index 000000000000..7d97372ca0df
--- /dev/null
+++ b/lib/pgalloc_tag.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/pgalloc_tag.h>
+#include <linux/seq_file.h>
+
+static __init bool need_page_alloc_tagging(void)
+{
+ return true;
+}
+
+static __init void init_page_alloc_tagging(void)
+{
+}
+
+struct page_ext_operations page_alloc_tagging_ops = {
+ .size = sizeof(union codetag_ref),
+ .need = need_page_alloc_tagging,
+ .init = init_page_alloc_tagging,
+};
+EXPORT_SYMBOL(page_alloc_tagging_ops);
+
diff --git a/mm/page_ext.c b/mm/page_ext.c
index 3dc715d7ac29..a22f514ff4da 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -9,6 +9,7 @@
#include <linux/page_owner.h>
#include <linux/page_idle.h>
#include <linux/page_table_check.h>
+#include <linux/pgalloc_tag.h>

/*
* struct page extension
@@ -76,6 +77,9 @@ static struct page_ext_operations *page_ext_ops[] __initdata = {
#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
&page_idle_ops,
#endif
+#ifdef CONFIG_PAGE_ALLOC_TAGGING
+ &page_alloc_tagging_ops,
+#endif
#ifdef CONFIG_PAGE_TABLE_CHECK
&page_table_check_ops,
#endif
@@ -152,6 +156,7 @@ struct page_ext *lookup_page_ext(const struct page *page)
MAX_ORDER_NR_PAGES);
return get_entry(base, index);
}
+EXPORT_SYMBOL(lookup_page_ext);

static int __init alloc_node_page_ext(int nid)
{
@@ -221,6 +226,7 @@ struct page_ext *lookup_page_ext(const struct page *page)
return NULL;
return get_entry(section->page_ext, pfn);
}
+EXPORT_SYMBOL(lookup_page_ext);

static void *__meminit alloc_page_ext(size_t size, int nid)
{
--
2.37.2.672.g94769d06f0-goog