[Xen-devel] [RFC PATCH v1 32/33] 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 enhances virtio_balloon driver to
adjust totalhigh_pages when reserve/unreserve pages.

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
---
 arch/tile/mm/init.c             |    4 ++--
 drivers/virtio/virtio_balloon.c |    8 +++++---
 drivers/xen/balloon.c           |   19 ++++---------------
 mm/hugetlb.c                    |    2 +-
 mm/memory_hotplug.c             |   15 +++------------
 mm/page_alloc.c                 |    6 ++++++
 6 files changed, 21 insertions(+), 33 deletions(-)

diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c
index 2749515..5886aef 100644
--- a/arch/tile/mm/init.c
+++ b/arch/tile/mm/init.c
@@ -720,7 +720,7 @@ static void __init init_free_pfn_range(unsigned long start, 
unsigned long end)
                }
                init_page_count(page);
                __free_pages(page, order);
-               totalram_pages += count;
+               adjust_managed_page_count(page, count);
 
                page += count;
                pfn += count;
@@ -1033,7 +1033,7 @@ static void free_init_pages(char *what, unsigned long 
begin, unsigned long end)
                                   pfn_pte(pfn, PAGE_KERNEL));
                memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
                free_page(addr);
-               totalram_pages++;
+               adjust_managed_page_count(page, 1);
        }
        pr_info("Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
 }
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 8dab163..4c6ec53 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 a56776d..a5fdbcc 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;
 }
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0a0be33..a381818 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 af9e87f..f9ce564 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 d252443..041eb92 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -780,7 +780,9 @@ void __init init_cma_reserved_pageblock(struct page *page)
 #ifdef CONFIG_HIGHMEM
        if (PageHighMem(page))
                totalhigh_pages += pageblock_nr_pages;
+       else
 #endif
+               page_zone(page)->managed_pages += pageblock_nr_pages;
 }
 #endif
 
@@ -5119,6 +5121,10 @@ 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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