It is too slow to dump all the pages, in some usage we just want dump
a given start pfn, for example: CMA range or a single page.
To speed up and save time, this change allows specify start pfn
by add llseek for page_onwer.
Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Kassey Li <quic_yingangl@xxxxxxxxxxx>
---
Documentation/mm/page_owner.rst | 5 +++++
mm/page_owner.c | 24 +++++++++++++++++++++---
2 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/Documentation/mm/page_owner.rst b/Documentation/mm/page_owner.rst
index f5c954afe97c..f18fd8907049 100644
--- a/Documentation/mm/page_owner.rst
+++ b/Documentation/mm/page_owner.rst
@@ -94,6 +94,11 @@ Usage
Page allocated via order XXX, ...
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
diff --git a/mm/page_owner.c b/mm/page_owner.c
index e4c6f3f1695b..25720d81bc26 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -497,8 +497,10 @@ 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 +563,7 @@ 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);
@@ -570,6 +572,21 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
return 0;
}
+static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig)
+{
+ switch (orig) {
+ case SEEK_SET:
+ file->f_pos = offset;
+ break;
+ case SEEK_CUR:
+ file->f_pos += offset;
+ break;
+ default:
+ return -EINVAL;
+ }
+ return file->f_pos;
+}
+
static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
{
unsigned long pfn = zone->zone_start_pfn;
@@ -660,6 +677,7 @@ static void init_early_allocated_pages(void)
static const struct file_operations proc_page_owner_operations = {
.read = read_page_owner,
+ .llseek = lseek_page_owner,
};
static int __init pageowner_init(void)
--
2.17.1
