On Thu, Sep 12, 2013 at 11:11:44AM -0400, Naoya Horiguchi wrote:
>Chen Gong pointed out that set/unset_migratetype_isolate() was done in
>different functions in mm/memory-failure.c, which makes the code less
>readable/maintenable. So this patch makes it done in soft_offline_page().
>
>With this patch, we get to hold lock_memory_hotplug() longer but it's not
>a problem because races between memory hotplug and soft offline are very rare.
>
>This patch is against next-20130910.
>
Reviewed-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
>Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
>Reviewed-by: Chen, Gong <gong.chen@xxxxxxxxxxxxxxx>
>---
> mm/memory-failure.c | 36 +++++++++++++++++-------------------
> 1 file changed, 17 insertions(+), 19 deletions(-)
>
>diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>index 947ed54..702e1e1 100644
>--- a/mm/memory-failure.c
>+++ b/mm/memory-failure.c
>@@ -1421,19 +1421,6 @@ static int __get_any_page(struct page *p, unsigned long pfn, int flags)
> return 1;
>
> /*
>- * The lock_memory_hotplug prevents a race with memory hotplug.
>- * This is a big hammer, a better would be nicer.
>- */
>- lock_memory_hotplug();
>-
>- /*
>- * Isolate the page, so that it doesn't get reallocated if it
>- * was free. This flag should be kept set until the source page
>- * is freed and PG_hwpoison on it is set.
>- */
>- if (get_pageblock_migratetype(p) != MIGRATE_ISOLATE)
>- set_migratetype_isolate(p, true);
>- /*
> * When the target page is a free hugepage, just remove it
> * from free hugepage list.
> */
>@@ -1453,7 +1440,6 @@ static int __get_any_page(struct page *p, unsigned long pfn, int flags)
> /* Not a free page */
> ret = 1;
> }
>- unlock_memory_hotplug();
> return ret;
> }
>
>@@ -1652,15 +1638,28 @@ int soft_offline_page(struct page *page, int flags)
> }
> }
>
>+ /*
>+ * The lock_memory_hotplug prevents a race with memory hotplug.
>+ * This is a big hammer, a better would be nicer.
>+ */
>+ lock_memory_hotplug();
>+
>+ /*
>+ * Isolate the page, so that it doesn't get reallocated if it
>+ * was free. This flag should be kept set until the source page
>+ * is freed and PG_hwpoison on it is set.
>+ */
>+ if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
>+ set_migratetype_isolate(page, true);
>+
> ret = get_any_page(page, pfn, flags);
>- if (ret < 0)
>- goto unset;
>- if (ret) { /* for in-use pages */
>+ unlock_memory_hotplug();
>+ if (ret > 0) { /* for in-use pages */
> if (PageHuge(page))
> ret = soft_offline_huge_page(page, flags);
> else
> ret = __soft_offline_page(page, flags);
>- } else { /* for free pages */
>+ } else if (ret == 0) { /* for free pages */
> if (PageHuge(page)) {
> set_page_hwpoison_huge_page(hpage);
> dequeue_hwpoisoned_huge_page(hpage);
>@@ -1671,7 +1670,6 @@ int soft_offline_page(struct page *page, int flags)
> atomic_long_inc(&num_poisoned_pages);
> }
> }
>-unset:
> unset_migratetype_isolate(page, MIGRATE_MOVABLE);
> return ret;
> }
>--
>1.8.3.1
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