Tool 'page-types' could list pages mapped by process or file cache pages,
but it shows only limited amount of state exported via procfs.
Let's employ existing helper dump_page() to reach remaining information:
writing pfn into /sys/kernel/debug/dump_page dumps state into kernel log.
# echo 0x37c43c > /sys/kernel/debug/dump_page
# dmesg | tail -6
page:ffffcb0b0df10f00 refcount:1 mapcount:0 mapping:000000007755d3d9 index:0x30
0xffffffffae4239e0 name:"libGeoIP.so.1.6.9"
flags: 0x200000000020014(uptodate|lru|mappedtodisk)
raw: 0200000000020014 ffffcb0b187fd288 ffffcb0b189e6248 ffff9528a04afe10
raw: 0000000000000030 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: debugfs request
With CONFIG_PAGE_OWNER=y shows also stacks for last page alloc and free:
page:ffffea0018fff480 refcount:1 mapcount:1 mapping:0000000000000000 index:0x7f9f28f62
anon flags: 0x100000000080034(uptodate|lru|active|swapbacked)
raw: 0100000000080034 ffffea00184140c8 ffffea0018517d88 ffff8886076ba161
raw: 00000007f9f28f62 0000000000000000 0000000100000000 ffff888bfc79f000
page dumped because: debugfs request
page->mem_cgroup:ffff888bfc79f000
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO)
prep_new_page+0x139/0x1a0
get_page_from_freelist+0xde9/0x14e0
__alloc_pages_nodemask+0x18b/0x360
alloc_pages_vma+0x7c/0x270
__handle_mm_fault+0xd40/0x12b0
handle_mm_fault+0xe7/0x1e0
do_page_fault+0x2d5/0x610
page_fault+0x2f/0x40
page last free stack trace:
free_pcp_prepare+0x11e/0x1c0
free_unref_page_list+0x71/0x180
release_pages+0x31e/0x480
tlb_flush_mmu+0x44/0x150
tlb_finish_mmu+0x3d/0x70
exit_mmap+0xdd/0x1a0
mmput+0x70/0x140
do_exit+0x33f/0xc40
do_group_exit+0x3a/0xa0
__x64_sys_exit_group+0x14/0x20
do_syscall_64+0x48/0x130
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
---
Documentation/admin-guide/mm/pagemap.rst | 3 +++
Documentation/vm/page_owner.rst | 10 ++++++++++
mm/debug.c | 27 +++++++++++++++++++++++++++
3 files changed, 40 insertions(+)
diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
index 340a5aee9b80..663ad5490d72 100644
--- a/Documentation/admin-guide/mm/pagemap.rst
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -205,3 +205,6 @@ Before Linux 3.11 pagemap bits 55-60 were used for "page-shift" (which is
always 12 at most architectures). Since Linux 3.11 their meaning changes
after first clear of soft-dirty bits. Since Linux 4.2 they are used for
flags unconditionally.
+
+Page state could be dumped into kernel log by writing pfn in text form
+into /sys/kernel/debug/dump_page.
diff --git a/Documentation/vm/page_owner.rst b/Documentation/vm/page_owner.rst
index 0ed5ab8c7ab4..d4d4dc64c19d 100644
--- a/Documentation/vm/page_owner.rst
+++ b/Documentation/vm/page_owner.rst
@@ -88,3 +88,13 @@ Usage
See the result about who allocated each page
in the ``sorted_page_owner.txt``.
+
+Notes
+=====
+
+To lookup pages in file cache or mapped in process you could use interface
+pagemap documented in Documentation/admin-guide/mm/pagemap.rst or tool
+page-types in the tools/vm directory.
+
+Page state could be dumped into kernel log by writing pfn in text form
+into /sys/kernel/debug/dump_page.
diff --git a/mm/debug.c b/mm/debug.c
index 2189357f0987..5803f2b63d95 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -14,6 +14,7 @@
#include <linux/migrate.h>
#include <linux/page_owner.h>
#include <linux/ctype.h>
+#include <linux/debugfs.h>
#include "internal.h"
@@ -147,6 +148,32 @@ void dump_page(struct page *page, const char *reason)
}
EXPORT_SYMBOL(dump_page);
+#ifdef CONFIG_DEBUG_FS
+static int dump_page_set(void *data, u64 pfn)
+{
+ struct page *page;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ page = pfn_to_online_page(pfn);
+ if (!page)
+ return -ENXIO;
+
+ dump_page(page, "debugfs request");
+ return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(dump_page_fops, NULL, dump_page_set, "%llx\n");
+
+static int __init dump_page_debugfs(void)
+{
+ debugfs_create_file_unsafe("dump_page", 0200, NULL, NULL,
+ &dump_page_fops);
+ return 0;
+}
+late_initcall(dump_page_debugfs);
+#endif /* CONFIG_DEBUG_FS */
+
#ifdef CONFIG_DEBUG_VM
void dump_vma(const struct vm_area_struct *vma)
