mm/page_reporting: export reporting order as module parameter

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.

Link: https://lkml.kernel.org/r/20210625014710.42954-3-gshan@redhat.com
Signed-off-by: Gavin Shan <gshan@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index cb89dbd..566c4b9 100644 (file)
--- 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).
+
        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 df9c505..34bf4d2 100644 (file)
--- 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);
 
        /*
         * 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 2c385dd..c51dbc2 100644 (file)
--- 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 */