Re: [PATCH v8, part3 12/14] mm: correctly update zone->mamaged_pages

[Wanpeng Li <liwanp@linux.vnet.ibm.com>]

On Sun, May 26, 2013 at 09:38:40PM +0800, Jiang Liu wrote:
>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@huawei.com>
>Cc: Chris Metcalf <cmetcalf@tilera.com>
>Cc: Rusty Russell <rusty@rustcorp.com.au>
>Cc: "Michael S. Tsirkin" <mst@redhat.com>
>Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>Cc: Jeremy Fitzhardinge <jeremy@goop.org>
>Cc: Wen Congyang <wency@cn.fujitsu.com>
>Cc: Andrew Morton <akpm@linux-foundation.org>
>Cc: Tang Chen <tangchen@cn.fujitsu.com>
>Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>Cc: Mel Gorman <mgorman@suse.de>
>Cc: Minchan Kim <minchan@kernel.org>
>Cc: linux-kernel@vger.kernel.org
>Cc: virtualization@lists.linux-foundation.org
>Cc: xen-devel@lists.xensource.com
>Cc: linux-mm@kvack.org
>---
> drivers/virtio/virtio_balloon.c |  8 +++++---
> drivers/xen/balloon.c           | 23 +++++------------------
> mm/hugetlb.c                    |  2 +-
> mm/memory_hotplug.c             | 16 +++-------------
> mm/page_alloc.c                 | 10 +++++-----
> 5 files changed, 19 insertions(+), 40 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 930fb68..c8aab4e 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;
> }
>@@ -372,9 +361,7 @@ 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 1a16ea0..7244e67 100644
>--- a/mm/memory_hotplug.c
>+++ b/mm/memory_hotplug.c
>@@ -772,20 +772,13 @@ 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);
>
>@@ -983,7 +976,6 @@ 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;
>
> 	pgdat_resize_lock(zone->zone_pgdat, &flags);
>@@ -1572,15 +1564,13 @@ 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;
>
> 	pgdat_resize_lock(zone->zone_pgdat, &flags);
> 	zone->zone_pgdat->node_present_pages -= offlined_pages;
> 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
>
>-	totalram_pages -= offlined_pages;
>-
> 	init_per_zone_wmark_min();
>
> 	if (!populated_zone(zone)) {
>diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>index 403afa6..5b27db4 100644
>--- a/mm/page_alloc.c
>+++ b/mm/page_alloc.c
>@@ -783,11 +783,7 @@ 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
>
>@@ -5232,6 +5228,10 @@ 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

Don't need CONFIG_HIGHMEM here.

Regards,
Wanpeng Li 

>+	if (PageHighMem(page))
>+		totalhigh_pages += count;
>+#endif
> 	spin_unlock(&managed_page_count_lock);
> }
> EXPORT_SYMBOL(adjust_managed_page_count);
>-- 
>1.8.1.2
>
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