[Xen-devel] [PATCH v4, part3 13/15] mm: correctly update zone->mamaged_pages

[Jiang Liu <liuj97@xxxxxxxxx>]

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@xxxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
---
 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 bacdf38..28757b7 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 6a600f1..f3b12d70 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -760,20 +760,13 @@ 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);
 
@@ -970,7 +963,6 @@ 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) {
@@ -1554,10 +1546,9 @@ 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 b87596f..4257a63 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
 
@@ -5192,6 +5188,10 @@ void adjust_managed_page_count(struct page *page, long 
count)
 
        page_zone(page)->managed_pages += count;
        totalram_pages += count;
+#ifdef CONFIG_HIGHMEM
+       if (PageHighMem(page))
+               totalhigh_pages += count;
+#endif
 
        if (lock)
                spin_unlock(&managed_page_count_lock);
-- 
1.7.9.5


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