+ mm-hugetlb-support-gigantic-surplus-pages.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: mm: hugetlb: support gigantic surplus pages
has been added to the -mm tree.  Its filename is
     mm-hugetlb-support-gigantic-surplus-pages.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-support-gigantic-surplus-pages.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-support-gigantic-surplus-pages.patch

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------------------------------------------------------
From: Huang Shijie <shijie.huang@arm.com>
Subject: mm: hugetlb: support gigantic surplus pages

When testing the gigantic page whose order is too large for the buddy
allocator, the libhugetlbfs test case "counter.sh" will fail.

The failure is caused by:
 1) kernel fails to allocate a gigantic page for the surplus case.
    And the gather_surplus_pages() will return NULL in the end.

 2) The condition checks for "over-commit" is wrong.

This patch uses __hugetlb_alloc_gigantic_page() to allocate the
gigantic page in the __alloc_huge_page(). After this patch,
 gather_surplus_pages() can return a gigantic page for the surplus case.

This patch also changes the condition checks for:

     return_unused_surplus_pages()
     nr_overcommit_hugepages_store()
     hugetlb_overcommit_handler()

After this patch, the counter.sh test can pass for the gigantic page.

Link: http://lkml.kernel.org/r/1479107259-2011-7-git-send-email-shijie.huang@arm.com
Signed-off-by: Huang Shijie <shijie.huang@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kirill A . Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Kaly Xin <kaly.xin@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff -puN mm/hugetlb.c~mm-hugetlb-support-gigantic-surplus-pages mm/hugetlb.c
--- a/mm/hugetlb.c~mm-hugetlb-support-gigantic-surplus-pages
+++ a/mm/hugetlb.c
@@ -1647,7 +1647,7 @@ static struct page *__alloc_huge_page(st
 	struct page *page;
 	unsigned int r_nid;
 
-	if (hstate_is_gigantic(h))
+	if (hstate_is_gigantic(h) && !gigantic_page_supported())
 		return NULL;
 
 	/*
@@ -1692,7 +1692,10 @@ static struct page *__alloc_huge_page(st
 	}
 	spin_unlock(&hugetlb_lock);
 
-	page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
+	if (hstate_is_gigantic(h))
+		page = __hugetlb_alloc_gigantic_page(h, vma, addr, nid);
+	else
+		page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
 
 	spin_lock(&hugetlb_lock);
 	if (page) {
@@ -1859,8 +1862,7 @@ static void return_unused_surplus_pages(
 	/* Uncommit the reservation */
 	h->resv_huge_pages -= unused_resv_pages;
 
-	/* Cannot return gigantic pages currently */
-	if (hstate_is_gigantic(h))
+	if (hstate_is_gigantic(h) && !gigantic_page_supported())
 		return;
 
 	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
@@ -2577,7 +2579,7 @@ static ssize_t nr_overcommit_hugepages_s
 	unsigned long input;
 	struct hstate *h = kobj_to_hstate(kobj, NULL);
 
-	if (hstate_is_gigantic(h))
+	if (hstate_is_gigantic(h) && !gigantic_page_supported())
 		return -EINVAL;
 
 	err = kstrtoul(buf, 10, &input);
@@ -3018,7 +3020,7 @@ int hugetlb_overcommit_handler(struct ct
 
 	tmp = h->nr_overcommit_huge_pages;
 
-	if (write && hstate_is_gigantic(h))
+	if (write && hstate_is_gigantic(h) && !gigantic_page_supported())
 		return -EINVAL;
 
 	table->data = &tmp;
_

Patches currently in -mm which might be from shijie.huang@arm.com are

mm-hugetlb-rename-some-allocation-functions.patch
mm-hugetlb-add-a-new-parameter-for-some-functions.patch
mm-hugetlb-change-the-return-type-for-alloc_fresh_gigantic_page.patch
mm-mempolicy-intruduce-a-helper-huge_nodemask.patch
mm-hugetlb-add-a-new-function-to-allocate-a-new-gigantic-page.patch
mm-hugetlb-support-gigantic-surplus-pages.patch