The patch titled
Subject: mm/hugetlb: improve locking in dissolve_free_huge_pages()
has been added to the -mm tree. Its filename is
mm-hugetlb-improve-locking-in-dissolve_free_huge_pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-improve-locking-in-dissolve_free_huge_pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-improve-locking-in-dissolve_free_huge_pages.patch
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------------------------------------------------------
From: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Subject: mm/hugetlb: improve locking in dissolve_free_huge_pages()
For every pfn aligned to minimum_order, dissolve_free_huge_pages() will
call dissolve_free_huge_page() which takes the hugetlb spinlock, even if
the page is not huge at all or a hugepage that is in-use.
Improve this by doing the PageHuge() and page_count() checks already in
dissolve_free_huge_pages() before calling dissolve_free_huge_page(). In
dissolve_free_huge_page(), when holding the spinlock, those checks need to
be revalidated.
Link: http://lkml.kernel.org/r/20160926172811.94033-4-gerald.schaefer@xxxxxxxxxx
Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Rui Teng <rui.teng@xxxxxxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff -puN mm/hugetlb.c~mm-hugetlb-improve-locking-in-dissolve_free_huge_pages mm/hugetlb.c
--- a/mm/hugetlb.c~mm-hugetlb-improve-locking-in-dissolve_free_huge_pages
+++ a/mm/hugetlb.c
@@ -1476,14 +1476,20 @@ out:
int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
+ struct page *page;
int rc = 0;
if (!hugepages_supported())
return rc;
- for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order)
- if (rc = dissolve_free_huge_page(pfn_to_page(pfn)))
- break;
+ for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
+ page = pfn_to_page(pfn);
+ if (PageHuge(page) && !page_count(page)) {
+ rc = dissolve_free_huge_page(page);
+ if (rc)
+ break;
+ }
+ }
return rc;
}
_
Patches currently in -mm which might be from gerald.schaefer@xxxxxxxxxx are
mm-hugetlb-fix-memory-offline-with-hugepage-size-memory-block-size.patch
mm-hugetlb-check-for-reserved-hugepages-during-memory-offline.patch
mm-hugetlb-improve-locking-in-dissolve_free_huge_pages.patch
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