On 6/25/21 3:53 PM, Michael S. Tsirkin wrote:
On Fri, Jun 25, 2021 at 09:47:08AM +0800, Gavin Shan wrote:
The macro PAGE_REPORTING_MIN_ORDER is defined as the page reporting
threshold. It can't be adjusted at runtime.
This introduces a variable (@page_reporting_order) to replace the
marcro (PAGE_REPORTING_MIN_ORDER). MAX_ORDER is assigned to it initially,
meaning the page reporting is disabled. It will be specified by driver
if valid one is provided. Otherwise, it will fall back to @pageblock_order.
It's also exported so that the page reporting order can be adjusted at
runtime.
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
Reviewed-by: Alexander Duyck <alexanderduyck@xxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
mm/page_reporting.c | 9 +++++++--
mm/page_reporting.h | 5 ++---
3 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index cb89dbdedc46..566c4b9af3cd 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3566,6 +3566,12 @@
off: turn off poisoning (default)
on: turn on poisoning
+ page_reporting.page_reporting_order=
+ [KNL] Minimal page reporting order
+ Format: <integer>
+ Adjust the minimal page reporting order. The page
+ reporting is disabled when it exceeds (MAX_ORDER-1).
Which the admin knows how? Run grep in the kernel source?
Well, I guess it's fine as it's used for debugging purpose. I guess
it's mostly used by developers. Also, the value can be changed by
the module parameter in "/sys/module/page_reporting" either.
+
panic= [KNL] Kernel behaviour on panic: delay <timeout>
timeout > 0: seconds before rebooting
timeout = 0: wait forever
diff --git a/mm/page_reporting.c b/mm/page_reporting.c
index df9c5054e1b4..34bf4d26c2c4 100644
--- a/mm/page_reporting.c
+++ b/mm/page_reporting.c
@@ -4,12 +4,17 @@
#include <linux/page_reporting.h>
#include <linux/gfp.h>
#include <linux/export.h>
+#include <linux/module.h>
#include <linux/delay.h>
#include <linux/scatterlist.h>
#include "page_reporting.h"
#include "internal.h"
+unsigned int page_reporting_order = MAX_ORDER;
+module_param(page_reporting_order, uint, 0644);
+MODULE_PARM_DESC(page_reporting_order, "Set page reporting order");
+
#define PAGE_REPORTING_DELAY (2 * HZ)
static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly;
@@ -229,7 +234,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev,
/* Generate minimum watermark to be able to guarantee progress */
watermark = low_wmark_pages(zone) +
- (PAGE_REPORTING_CAPACITY << PAGE_REPORTING_MIN_ORDER);
+ (PAGE_REPORTING_CAPACITY << page_reporting_order);
Looks like this makes it easy to trigger undefined behaviour. Just use
any value > 31.
This function won't be run if page_reporting_order is more than (MAX_ORDER-1).
/*
* Cancel request if insufficient free memory or if we failed
@@ -239,7 +244,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev,
return err;
/* Process each free list starting from lowest order/mt */
- for (order = PAGE_REPORTING_MIN_ORDER; order < MAX_ORDER; order++) {
+ for (order = page_reporting_order; order < MAX_ORDER; order++) {
for (mt = 0; mt < MIGRATE_TYPES; mt++) {
/* We do not pull pages from the isolate free list */
if (is_migrate_isolate(mt))
diff --git a/mm/page_reporting.h b/mm/page_reporting.h
index 2c385dd4ddbd..c51dbc228b94 100644
--- a/mm/page_reporting.h
+++ b/mm/page_reporting.h
@@ -10,10 +10,9 @@
#include <linux/pgtable.h>
#include <linux/scatterlist.h>
-#define PAGE_REPORTING_MIN_ORDER pageblock_order
-
#ifdef CONFIG_PAGE_REPORTING
DECLARE_STATIC_KEY_FALSE(page_reporting_enabled);
+extern unsigned int page_reporting_order;
void __page_reporting_notify(void);
static inline bool page_reported(struct page *page)
@@ -38,7 +37,7 @@ static inline void page_reporting_notify_free(unsigned int order)
return;
/* Determine if we have crossed reporting threshold */
- if (order < PAGE_REPORTING_MIN_ORDER)
+ if (order < page_reporting_order)
return;
/* This will add a few cycles, but should be called infrequently */
--
2.23.0
Thanks,
Gavin
