[RFC][PATCH 3/4] filemap: implement filemap allocate post callback for page_owner

[Jeff Xie]

Implement the callback function filemap_alloc_post_page_owner for the page_owner
to make the owner of the file page clearer

For the pid 98:
[root@JeffXie ]# cat /proc/98/maps 
00400000-00401000 r--p 00000000 fd:00 1954	/test/mm/a.out
00401000-00499000 r-xp 00001000 fd:00 1954      /test/mm/a.out
00499000-004c2000 r--p 00099000 fd:00 1954      /test/mm/a.out
004c2000-004c6000 r--p 000c1000 fd:00 1954      /test/mm/a.out
004c6000-004c9000 rw-p 000c5000 fd:00 1954      /test/mm/a.out
004c9000-004ce000 rw-p 00000000 00:00 0 
01d97000-01db9000 rw-p 00000000 00:00 0                 [heap]
7f1588fc8000-7f1588fc9000 rw-p 00000000 fd:00 1945      /a.txt
7ffda207a000-7ffda209b000 rw-p 00000000 00:00 0         [stack]
7ffda2152000-7ffda2156000 r--p 00000000 00:00 0         [vvar]
7ffda2156000-7ffda2158000 r-xp 00000000 00:00 0         [vdso]
ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall]

added: "FILE_PAGE dev 253:0 ino:1954 index:0xc1 mapcount:1 refcount:2 0x4c2000 - 0x4c3000"

Page allocated via order 0, mask 0x152c4a(GFP_NOFS|__GFP_HIGHMEM|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE),\
 pid 98, tgid 98 (a.out), ts 28441476044 ns
FILE_PAGE dev 253:0 ino:1954 index:0xc1 mapcount:1 refcount:2 0x4c2000 - 0x4c3000
PFN 0x5be8e type Movable Block 735 type Movable Flags 0x1fffc0000020028(uptodate|lru|mappedtodisk|node=0|zone=1|lastcpupid=0x3fff)
 post_alloc_hook+0x77/0xf0
 get_page_from_freelist+0x58d/0x14e0
 __alloc_pages+0x1b2/0x380
 alloc_pages_mpol+0x97/0x1f0
 folio_alloc+0x18/0x50
 page_cache_ra_unbounded+0x9b/0x1a0
 filemap_fault+0x5f7/0xc20
 __do_fault+0x31/0xc0
 __handle_mm_fault+0x1333/0x1760
 handle_mm_fault+0xbc/0x2f0
 do_user_addr_fault+0x1f8/0x5e0
 exc_page_fault+0x73/0x170
 asm_exc_page_fault+0x26/0x30
Charged to memcg / 

Signed-off-by: Jeff Xie <jeff.xie@xxxxxxxxx>
---
 include/linux/pagemap.h |  7 +++++++
 mm/filemap.c            | 44 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index bcc1ea44b4e8..900aa136c71f 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -1514,4 +1514,11 @@ unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
 {
 	return i_blocks_per_folio(inode, page_folio(page));
 }
+#ifndef CONFIG_PAGE_OWNER
+static inline int filemap_alloc_post_page_owner(struct folio *folio, struct task_struct *tsk,
+		void *data, char *kbuf, size_t count)
+{
+	return 0;
+}
+#endif
 #endif /* _LINUX_PAGEMAP_H */
diff --git a/mm/filemap.c b/mm/filemap.c
index 9710f43a89ac..0a346443309a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -45,6 +45,7 @@
 #include <linux/migrate.h>
 #include <linux/pipe_fs_i.h>
 #include <linux/splice.h>
+#include <linux/page_owner.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include "internal.h"
@@ -838,6 +839,48 @@ void replace_page_cache_folio(struct folio *old, struct folio *new)
 }
 EXPORT_SYMBOL_GPL(replace_page_cache_folio);
 
+#ifdef CONFIG_PAGE_OWNER
+static int filemap_alloc_post_page_owner(struct folio *folio, struct task_struct *tsk,
+			void *data, char *kbuf, size_t count)
+{
+	int ret;
+	int mapcount;
+	dev_t s_dev;
+	struct inode *inode;
+	struct vm_area_struct *vma;
+	struct mm_struct *mm;
+	unsigned long virtual_start = 0x0;
+	unsigned long virtual_end = 0x0;
+	struct address_space *mapping = data;
+
+	mapcount = folio_mapcount(folio);
+	if (mapcount && tsk && tsk->mm) {
+		mm = tsk->mm;
+		VMA_ITERATOR(vmi, mm, 0);
+		mmap_read_lock(mm);
+		for_each_vma(vmi, vma) {
+			if (page_mapped_in_vma(&folio->page, vma)) {
+				virtual_start = vma_address(&folio->page, vma);
+				virtual_end = virtual_start + folio_nr_pages(folio) * PAGE_SIZE;
+				break;
+			}
+		}
+		mmap_read_unlock(mm);
+	}
+
+	inode = mapping->host;
+	if (mapping->host->i_sb)
+		s_dev = mapping->host->i_sb->s_dev;
+	else
+		s_dev = mapping->host->i_rdev;
+	ret = scnprintf(kbuf, count, "FILE_PAGE dev %d:%d ino:%lu index:0x%lx mapcount:%d refcount:%d 0x%lx - 0x%lx\n",
+		MAJOR(s_dev), MINOR(s_dev), inode->i_ino, folio->index, mapcount, folio_ref_count(folio),
+		virtual_start, virtual_end);
+
+	return ret;
+}
+#endif
+
 noinline int __filemap_add_folio(struct address_space *mapping,
 		struct folio *folio, pgoff_t index, gfp_t gfp, void **shadowp)
 {
@@ -915,6 +958,7 @@ noinline int __filemap_add_folio(struct address_space *mapping,
 	if (xas_error(&xas))
 		goto error;
 
+	set_folio_alloc_post_page_owner(folio, filemap_alloc_post_page_owner, mapping);
 	trace_mm_filemap_add_to_page_cache(folio);
 	return 0;
 error:
-- 
2.34.1