From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.kundenserver.de ([212.227.126.187]:61369 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755521AbdEETsU (ORCPT ); Fri, 5 May 2017 15:48:20 -0400 From: Arnd Bergmann To: Ben Hutchings Cc: stable@vger.kernel.org, Gerald Schaefer , "Kirill A . Shutemov" , Vlastimil Babka , Mike Kravetz , "Aneesh Kumar K . V" , Martin Schwidefsky , Heiko Carstens , Rui Teng , Dave Hansen , Andrew Morton , Linus Torvalds , Arnd Bergmann Subject: [PATCH 3.16-stable 07/87] mm/hugetlb: improve locking in dissolve_free_huge_pages() Date: Fri, 5 May 2017 21:46:25 +0200 Message-Id: <20170505194745.3627137-8-arnd@arndb.de> In-Reply-To: <20170505194745.3627137-1-arnd@arndb.de> References: <20170505194745.3627137-1-arnd@arndb.de> Sender: stable-owner@vger.kernel.org List-ID: From: Gerald Schaefer Commit 7b21d5b87b550c5cdaca73bd37c976cc1ab85398 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.schaefer@de.ibm.com Signed-off-by: Gerald Schaefer Acked-by: Michal Hocko Acked-by: Naoya Horiguchi Cc: "Kirill A . Shutemov" Cc: Vlastimil Babka Cc: Mike Kravetz Cc: "Aneesh Kumar K . V" Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Rui Teng Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Arnd Bergmann --- mm/hugetlb.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 467d04b62948..c892a6b51e8e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1105,14 +1105,20 @@ 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; } -- 2.9.0