From 3254948484899b7e066496af41c3a523b529c394 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@google.com>
Date: Sun, 11 Jul 2021 12:43:11 -0700
Subject: [PATCH] ANDROID: mm: page_pinner: add more struct page fields

While I was investigating CMA allocation latency, adding fields below
were very useful to detect the CMA allocation latency issues.
This patch adds following fields of struct page.

for struct page:

  int count
  int mapcount
  struct address_space

This patch removes page_mt since it was not useful ever for me.

Bug: 192475091
Signed-off-by: Minchan Kim <minchan@google.com>
Change-Id: I312505901a227cd404555f845550d2a9c9ce89da
---
 mm/page_pinner.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/mm/page_pinner.c b/mm/page_pinner.c
index 0245881aadeb..64b1e4154561 100644
--- a/mm/page_pinner.c
+++ b/mm/page_pinner.c
@@ -29,9 +29,13 @@ struct captured_pinner {
 		s64 ts_usec;
 		s64 elapsed;
 	};
-	int page_mt;
-	unsigned long page_flags;
+
+	/* struct page fields */
 	unsigned long pfn;
+	int count;
+	int mapcount;
+	struct address_space *mapping;
+	unsigned long flags;
 };
 
 struct longterm_pinner {
@@ -117,9 +121,11 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
 static void capture_page_state(struct page *page,
 			       struct captured_pinner *record)
 {
-	record->page_flags = page->flags;
-	record->page_mt = get_pageblock_migratetype(page);
+	record->flags = page->flags;
+	record->mapping = page_mapping(page);
 	record->pfn = page_to_pfn(page);
+	record->count = page_count(page);
+	record->mapcount = page_mapcount(page);
 }
 
 static void check_longterm_pin(struct page_pinner *page_pinner,
@@ -238,11 +244,12 @@ print_page_pinner(bool longterm, char __user *buf, size_t count, struct captured
 
 	/* Print information relevant to grouping pages by mobility */
 	ret += snprintf(kbuf + ret, count - ret,
-			"PFN %lu Block %lu type %s Flags %#lx(%pGp)\n",
+			"PFN 0x%lx Block %lu count %d mapcount %d mapping %pS Flags %#lx(%pGp)\n",
 			record->pfn,
 			record->pfn >> pageblock_order,
-			migratetype_names[record->page_mt],
-			record->page_flags, &record->page_flags);
+			record->count, record->mapcount,
+			record->mapping,
+			record->flags, &record->flags);
 
 	if (ret >= count)
 		goto err;