4.8-stable review patch. If anyone has any objections, please let me know.
------------------ From: Gerald Schaefer <gerald.schae...@de.ibm.com> commit eb03aa008561004257900983193d024e57abdd96 upstream. 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.schae...@de.ibm.com Signed-off-by: Gerald Schaefer <gerald.schae...@de.ibm.com> Acked-by: Michal Hocko <mho...@suse.com> Acked-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com> Cc: "Kirill A . Shutemov" <kirill.shute...@linux.intel.com> Cc: Vlastimil Babka <vba...@suse.cz> Cc: Mike Kravetz <mike.krav...@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.ku...@linux.vnet.ibm.com> Cc: Martin Schwidefsky <schwidef...@de.ibm.com> Cc: Heiko Carstens <heiko.carst...@de.ibm.com> Cc: Rui Teng <rui.t...@linux.vnet.ibm.com> Cc: Dave Hansen <dave.han...@linux.intel.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- mm/hugetlb.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/mm/hugetlb.c +++ b/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; }
