Xen devel - May 2013 - [PATCH v6, part3 13/16] mm: correctly update zone->mamaged_pages

Enhance adjust_managed_page_count() to adjust totalhigh_pages for
highmem pages. And change code which directly adjusts totalram_pages
to use adjust_managed_page_count() because it adjusts totalram_pages,
totalhigh_pages and zone->managed_pages altogether in a safe way.

Remove inc_totalhigh_pages() and dec_totalhigh_pages() from xen/balloon
driver bacause adjust_managed_page_count() has already adjusted
totalhigh_pages.

This patch also fixes two bugs:
1) enhances virtio_balloon driver to adjust totalhigh_pages when
   reserve/unreserve pages.
2) enhance memory_hotplug.c to adjust totalhigh_pages when hot-removing
   memory.

We still need to deal with modifications of totalram_pages in file
arch/powerpc/platforms/pseries/cmm.c, but need help from PPC experts.

Signed-off-by: Jiang Liu <jiang.liu at huawei.com>
Cc: Chris Metcalf <cmetcalf at tilera.com>
Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst at redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Cc: Jeremy Fitzhardinge <jeremy at goop.org>
Cc: Wen Congyang <wency at cn.fujitsu.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Tang Chen <tangchen at cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki at jp.fujitsu.com>
Cc: Mel Gorman <mgorman at suse.de>
Cc: Minchan Kim <minchan at kernel.org>
Cc: linux-kernel at vger.kernel.org
Cc: virtualization at lists.linux-foundation.org
Cc: xen-devel at lists.xensource.com
Cc: linux-mm at kvack.org
---
 drivers/virtio/virtio_balloon.c |  8 +++++---
 drivers/xen/balloon.c           | 23 +++++------------------
 mm/hugetlb.c                    |  2 +-
 mm/memory_hotplug.c             | 15 +++------------
 mm/page_alloc.c                 | 10 +++++-----
 5 files changed, 19 insertions(+), 39 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index bd3ae32..6649968 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -148,7 +148,7 @@ static void fill_balloon(struct virtio_balloon *vb, size_t
num)
 		}
 		set_page_pfns(vb->pfns + vb->num_pfns, page);
 		vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
-		totalram_pages--;
+		adjust_managed_page_count(page, -1);
 	}
 
 	/* Did we get any? */
@@ -160,11 +160,13 @@ static void fill_balloon(struct virtio_balloon *vb, size_t
num)
 static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
 {
 	unsigned int i;
+	struct page *page;
 
 	/* Find pfns pointing at start of each page, get pages and free them. */
 	for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
-		balloon_page_free(balloon_pfn_to_page(pfns[i]));
-		totalram_pages++;
+		page = balloon_pfn_to_page(pfns[i]);
+		balloon_page_free(page);
+		adjust_managed_page_count(page, 1);
 	}
 }
 
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index d42da3b..a453c05 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -89,14 +89,6 @@ EXPORT_SYMBOL_GPL(balloon_stats);
 /* We increase/decrease in batches which fit in a page */
 static xen_pfn_t frame_list[PAGE_SIZE / sizeof(unsigned long)];
 
-#ifdef CONFIG_HIGHMEM
-#define inc_totalhigh_pages() (totalhigh_pages++)
-#define dec_totalhigh_pages() (totalhigh_pages--)
-#else
-#define inc_totalhigh_pages() do {} while (0)
-#define dec_totalhigh_pages() do {} while (0)
-#endif
-
 /* List of ballooned pages, threaded through the mem_map array. */
 static LIST_HEAD(ballooned_pages);
 
@@ -132,9 +124,7 @@ static void __balloon_append(struct page *page)
 static void balloon_append(struct page *page)
 {
 	__balloon_append(page);
-	if (PageHighMem(page))
-		dec_totalhigh_pages();
-	totalram_pages--;
+	adjust_managed_page_count(page, -1);
 }
 
 /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
@@ -151,13 +141,12 @@ static struct page *balloon_retrieve(bool prefer_highmem)
 		page = list_entry(ballooned_pages.next, struct page, lru);
 	list_del(&page->lru);
 
-	if (PageHighMem(page)) {
+	if (PageHighMem(page))
 		balloon_stats.balloon_high--;
-		inc_totalhigh_pages();
-	} else
+	else
 		balloon_stats.balloon_low--;
 
-	totalram_pages++;
+	adjust_managed_page_count(page, 1);
 
 	return page;
 }
@@ -374,9 +363,7 @@ static enum bp_state increase_reservation(unsigned long
nr_pages)
 #endif
 
 		/* Relinquish the page back to the allocator. */
-		ClearPageReserved(page);
-		init_page_count(page);
-		__free_page(page);
+		__free_reserved_page(page);
 	}
 
 	balloon_stats.current_pages += rc;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index f8feeec..95c5a6b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1246,7 +1246,7 @@ static void __init gather_bootmem_prealloc(void)
 		 * side-effects, like CommitLimit going negative.
 		 */
 		if (h->order > (MAX_ORDER - 1))
-			totalram_pages += 1 << h->order;
+			adjust_managed_page_count(page, 1 << h->order);
 	}
 }
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c291295..304ada7 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -769,20 +769,13 @@ EXPORT_SYMBOL_GPL(__online_page_set_limits);
 
 void __online_page_increment_counters(struct page *page)
 {
-	totalram_pages++;
-
-#ifdef CONFIG_HIGHMEM
-	if (PageHighMem(page))
-		totalhigh_pages++;
-#endif
+	adjust_managed_page_count(page, 1);
 }
 EXPORT_SYMBOL_GPL(__online_page_increment_counters);
 
 void __online_page_free(struct page *page)
 {
-	ClearPageReserved(page);
-	init_page_count(page);
-	__free_page(page);
+	__free_reserved_page(page);
 }
 EXPORT_SYMBOL_GPL(__online_page_free);
 
@@ -979,7 +972,6 @@ int __ref online_pages(unsigned long pfn, unsigned long
nr_pages, int online_typ
 		return ret;
 	}
 
-	zone->managed_pages += onlined_pages;
 	zone->present_pages += onlined_pages;
 	zone->zone_pgdat->node_present_pages += onlined_pages;
 	if (onlined_pages) {
@@ -1563,10 +1555,9 @@ repeat:
 	/* reset pagetype flags and makes migrate type to be MOVABLE */
 	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 	/* removal success */
-	zone->managed_pages -= offlined_pages;
+	adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);
 	zone->present_pages -= offlined_pages;
 	zone->zone_pgdat->node_present_pages -= offlined_pages;
-	totalram_pages -= offlined_pages;
 
 	init_per_zone_wmark_min();
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a07e70a..56b0097 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -780,11 +780,7 @@ void __init init_cma_reserved_pageblock(struct page *page)
 	set_page_refcounted(page);
 	set_pageblock_migratetype(page, MIGRATE_CMA);
 	__free_pages(page, pageblock_order);
-	totalram_pages += pageblock_nr_pages;
-#ifdef CONFIG_HIGHMEM
-	if (PageHighMem(page))
-		totalhigh_pages += pageblock_nr_pages;
-#endif
+	adjust_managed_page_count(page, pageblock_nr_pages);
 }
 #endif
 
@@ -5189,6 +5185,10 @@ void adjust_managed_page_count(struct page *page, long
count)
 	spin_lock(&managed_page_count_lock);
 	page_zone(page)->managed_pages += count;
 	totalram_pages += count;
+#ifdef	CONFIG_HIGHMEM
+	if (PageHighMem(page))
+		totalhigh_pages += count;
+#endif
 	spin_unlock(&managed_page_count_lock);
 }
 EXPORT_SYMBOL(adjust_managed_page_count);
-- 
1.8.1.2