The patch titled
Subject: mm/page_owner.c: add llseek for page_owner
has been added to the -mm mm-unstable branch. Its filename is
mm-page_ownerc-add-llseek-for-page_owner.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_ownerc-add-llseek-for-page_owner.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kassey Li <quic_yingangl@xxxxxxxxxxx>
Subject: mm/page_owner.c: add llseek for page_owner
Date: Thu, 18 Aug 2022 10:24:25 +0800
It is too slow to dump all the pages, in some usage we just want to dump a
given start pfn, for example: a CMA range or a single page.
To speed up and save time, this change allows specifying of a start pfn by
adding llseek for page_owner.
Link: https://lkml.kernel.org/r/20220818022425.31056-1-quic_yingangl@xxxxxxxxxxx
Signed-off-by: Kassey Li <quic_yingangl@xxxxxxxxxxx>
Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/mm/page_owner.rst | 5 +++++
mm/page_owner.c | 24 +++++++++++++++++++++---
2 files changed, 26 insertions(+), 3 deletions(-)
--- a/Documentation/mm/page_owner.rst~mm-page_ownerc-add-llseek-for-page_owner
+++ a/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
--- a/mm/page_owner.c~mm-page_ownerc-add-llseek-for-page_owner
+++ a/mm/page_owner.c
@@ -516,8 +516,10 @@ read_page_owner(struct file *file, char
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++;
@@ -588,7 +590,7 @@ read_page_owner(struct file *file, char
goto loop;
/* Record the next PFN to read in the file offset */
- *ppos = (pfn - min_low_pfn) + 1;
+ *ppos = pfn + 1;
page_owner_tmp = *page_owner;
page_ext_put(page_ext);
@@ -601,6 +603,21 @@ loop:
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;
@@ -693,6 +710,7 @@ static void init_early_allocated_pages(v
static const struct file_operations proc_page_owner_operations = {
.read = read_page_owner,
+ .llseek = lseek_page_owner,
};
static int __init pageowner_init(void)
_
Patches currently in -mm which might be from quic_yingangl@xxxxxxxxxxx are
mm-page_ownerc-add-llseek-for-page_owner.patch
