From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f48.google.com (mail-oi0-f48.google.com [209.85.218.48]) by kanga.kvack.org (Postfix) with ESMTP id 0C08A6B0073 for ; Wed, 27 May 2015 13:59:20 -0400 (EDT) Received: by oifu123 with SMTP id u123so13686067oif.1 for ; Wed, 27 May 2015 10:59:19 -0700 (PDT) Received: from userp1040.oracle.com (userp1040.oracle.com. [156.151.31.81]) by mx.google.com with ESMTPS id z9si13136oey.5.2015.05.27.10.59.18 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 May 2015 10:59:18 -0700 (PDT) From: Mike Kravetz Subject: [PATCH v3 3/3] mm/hugetlb: handle races in alloc_huge_page and hugetlb_reserve_pages Date: Wed, 27 May 2015 10:56:11 -0700 Message-Id: <1432749371-32220-4-git-send-email-mike.kravetz@oracle.com> In-Reply-To: <1432749371-32220-1-git-send-email-mike.kravetz@oracle.com> References: <1432749371-32220-1-git-send-email-mike.kravetz@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Naoya Horiguchi , Davidlohr Bueso , David Rientjes , Luiz Capitulino , Andrew Morton , Mike Kravetz alloc_huge_page and hugetlb_reserve_pages use region_chg to calculate the number of pages which will be added to the reserve map. Subpool and global reserve counts are adjusted based on the output of region_chg. Before the pages are actually added to the reserve map, these routines could race and add fewer pages than expected. If this happens, the subpool and global reserve counts are not correct. Compare the number of pages actually added (region_add) to those expected to added (region_chg). If fewer pages are actually added, this indicates a race and adjust counters accordingly. Signed-off-by: Mike Kravetz --- mm/hugetlb.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index b3d3d59..038c84e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1544,7 +1544,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, struct hugepage_subpool *spool = subpool_vma(vma); struct hstate *h = hstate_vma(vma); struct page *page; - long chg; + long chg, commit; int ret, idx; struct hugetlb_cgroup *h_cg; @@ -1585,7 +1585,20 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, set_page_private(page, (unsigned long)spool); - vma_commit_reservation(h, vma, addr); + commit = vma_commit_reservation(h, vma, addr); + if (unlikely(chg > commit)) { + /* + * The page was added to the reservation map between + * vma_needs_reservation and vma_commit_reservation. + * This indicates a race with hugetlb_reserve_pages. + * Adjust for the subpool count incremented above AND + * in hugetlb_reserve_pages for the same page. Also, + * the reservation count added in hugetlb_reserve_pages + * no longer applies. + */ + hugepage_subpool_put_pages(spool, 1); + hugetlb_acct_memory(h, -1); + } return page; out_uncharge_cgroup: @@ -3699,8 +3712,21 @@ int hugetlb_reserve_pages(struct inode *inode, * consumed reservations are stored in the map. Hence, nothing * else has to be done for private mappings here */ - if (!vma || vma->vm_flags & VM_MAYSHARE) - region_add(resv_map, from, to); + if (!vma || vma->vm_flags & VM_MAYSHARE) { + long add = region_add(resv_map, from, to); + + if (unlikely(chg > add)) { + /* + * pages in this range were added to the reserve + * map between region_chg and region_add. This + * indicates a race with alloc_huge_page. Adjust + * the subpool and reserve counts modified above + * based on the difference. + */ + hugepage_subpool_put_pages(spool, chg - add); + hugetlb_acct_memory(h, -(chg - ret)); + } + } return 0; out_err: if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) -- 2.1.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org