mm/hugetlb: fix incorrect hugepages count during mem hotplug

When memory hotplug operates, free hugepages will be freed if the
movable node is offline.  Therefore, /proc/sys/vm/nr_hugepages will be
incorrect.

Fix it by reducing max_huge_pages when the node is offlined.

[email protected] said:

: dissolve_free_huge_page intends to break a hugepage into buddy, and the
: destination hugepage is supposed to be allocated from the pool of the
: destination node, so the system-wide pool size is reduced.  So adding
: h->max_huge_pages-- makes sense to me.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: zhong jiang <[email protected]>
Cc: Mike Kravetz <[email protected]>
Acked-by: Naoya Horiguchi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index b9aa1b0b38b0ecdb769cd33a8d77c0ffda2621bf..87e11d8ad536b8c360740ca9ce96461b0daeaaee 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1448,6 +1448,7 @@ static void dissolve_free_huge_page(struct page *page)
                list_del(&page->lru);
                h->free_huge_pages--;
                h->free_huge_pages_node[nid]--;
+               h->max_huge_pages--;
                update_and_free_page(h, page);
        }
        spin_unlock(&hugetlb_lock);