There is usage to dump a given cma region page_owner
instead of all page's.
This change allows to specify a ppos as start_pfn
by fseek.
Any invalid ppos will be skipped, so it did not
broken the origin dump feature.
Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Kassey Li <quic_yingangl@xxxxxxxxxxx>
---
Documentation/vm/page_owner.rst | 6 ++++++
mm/page_owner.c | 10 +++++++---
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/Documentation/vm/page_owner.rst b/Documentation/vm/page_owner.rst
index f5c954afe97c..8d33d976da8a 100644
--- a/Documentation/vm/page_owner.rst
+++ b/Documentation/vm/page_owner.rst
@@ -95,6 +95,12 @@ Usage
PFN XXX ...
// Detailed stack
+ By default, it will do full pfn dump, to start with a given pfn,
+ page_owner supports fseek.
+
+ FILE *fp = fopen("/sys/kernel/debug/page_owner", "r");
+ fseek(fp, pfn_start, SEEK_SET);
+
The ``page_owner_sort`` tool ignores ``PFN`` rows, puts the remaining rows
in buf, uses regexp to extract the page order value, counts the times
and pages of buf, and finally sorts them according to the parameter(s).
diff --git a/mm/page_owner.c b/mm/page_owner.c
index e4c6f3f1695b..33832b5908e6 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -13,6 +13,7 @@
#include <linux/memcontrol.h>
#include <linux/sched/clock.h>
+#include "../fs/proc/internal.h"
#include "internal.h"
/*
@@ -497,8 +498,10 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
return -EINVAL;
page = NULL;
- pfn = min_low_pfn + *ppos;
-
+ if (*ppos == 0)
+ pfn = min_low_pfn;
+ else
+ pfn = *ppos;
/* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
pfn++;
@@ -561,7 +564,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
continue;
/* Record the next PFN to read in the file offset */
- *ppos = (pfn - min_low_pfn) + 1;
+ *ppos = pfn + 1;
return print_page_owner(buf, count, pfn, page,
page_owner, handle);
@@ -660,6 +663,7 @@ static void init_early_allocated_pages(void)
static const struct file_operations proc_page_owner_operations = {
.read = read_page_owner,
+ .llseek = mem_lseek,
};
static int __init pageowner_init(void)
--
2.17.1
