From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28A0CC432C0 for ; Sun, 1 Dec 2019 01:56:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E014F2082E for ; Sun, 1 Dec 2019 01:56:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="mXybSIMf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E014F2082E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 902B26B0349; Sat, 30 Nov 2019 20:56:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 88D326B034B; Sat, 30 Nov 2019 20:56:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6E22A6B034C; Sat, 30 Nov 2019 20:56:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0137.hostedemail.com [216.40.44.137]) by kanga.kvack.org (Postfix) with ESMTP id 548246B0349 for ; Sat, 30 Nov 2019 20:56:17 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 08A63180AD817 for ; Sun, 1 Dec 2019 01:56:17 +0000 (UTC) X-FDA: 76214907594.25.wing73_36d1b283d713a X-HE-Tag: wing73_36d1b283d713a X-Filterd-Recvd-Size: 4892 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Sun, 1 Dec 2019 01:56:16 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 852FE2084D; Sun, 1 Dec 2019 01:56:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575165375; bh=SaBTKBsd7mt6lHS/YOr773gnLBMgslZzLgdw1dfwTAY=; h=Date:From:To:Subject:From; b=mXybSIMfyXpr7KCPZHv3i9P7+vlKliXmzAKL57KTQqgx0WToYK7q/FvgWIBeOyrBI xTs3/MOSv4bQf5W6lQcVUwQJlAV4I6R4OE/evBwBOY+/6CCArOxCa0h6zQo6iXPAms UgxUNLu8VszY1bA6PqrR0JBTmOnMYzx/6It3gVG0= Date: Sat, 30 Nov 2019 17:56:15 -0800 From: akpm@linux-foundation.org To: akpm@linux-foundation.org, hughd@google.com, linux-man@vger.kernel.org, linux-mm@kvack.org, lixinhai.lxh@gmail.com, mhocko@suse.com, mm-commits@vger.kernel.org, n-horiguchi@ah.jp.nec.com, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 118/158] mm/mempolicy.c: check range first in queue_pages_test_walk Message-ID: <20191201015615.KPQyOXwfq%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Li Xinhai Subject: mm/mempolicy.c: check range first in queue_pages_test_walk Patch series "mm: Fix checking unmapped holes for mbind", v4. This patchset fix checking unmapped holes for mbind(). First patch makes sure the vma been correctly tracked in .test_walk(), so each time when .test_walk() is called, the neighborhood of two vma is correct. Current problem is that the !vma_migratable() check could cause return immediately without update tracking to vma. Second patch fix the inconsistent report of EFAULT when mbind() is called for MPOL_DEFAULT and non MPOL_DEFAULT cases, so application do not need to have workaround code to handle this special behavior. Currently there are two problems, one is that the .test_walk() can not know there is hole at tail side of range, because .test_walk() only call for vma not for hole. The other one is that mbind_range() checks for hole at head side of range but do not consider the MPOL_MF_DISCONTIG_OK flag as done in .test_walk(). This patch (of 2): Checking unmapped hole and updating the previous vma must be handled first, otherwise the unmapped hole could be calculated from a wrong previous vma. Several commits were relevant to this error: commit 6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()"), This commit was correct, the VM_PFNMAP check was after updating previous vma commit 48684a65b4e3 (mm: pagewalk: fix misbehavior of walk_page_range for vma(VM_PFNMAP)), This commit added VM_PFNMAP check before updating previous vma. Then, there were two VM_PFNMAP check did same thing twice. commit acda0c334028 (mm/mempolicy.c: get rid of duplicated check for vma(VM_PFNMAP) in queue_page s_range()), This commit tried to fix the duplicated VM_PFNMAP check, but it wrongly removed the one which was after updating vma. Link: http://lkml.kernel.org/r/1573218104-11021-2-git-send-email-lixinhai.lxh@gmail.com Fixes: acda0c334028 (mm/mempolicy.c: get rid of duplicated check for vma(VM_PFNMAP) in queue_pages_range()) Signed-off-by: Li Xinhai Reviewed-by: Naoya Horiguchi Cc: Michal Hocko Cc: Vlastimil Babka Cc: Hugh Dickins Cc: linux-man Signed-off-by: Andrew Morton --- mm/mempolicy.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) --- a/mm/mempolicy.c~mm-check-range-first-in-queue_pages_test_walk +++ a/mm/mempolicy.c @@ -618,6 +618,16 @@ static int queue_pages_test_walk(unsigne unsigned long endvma = vma->vm_end; unsigned long flags = qp->flags; + /* range check first */ + if (!(flags & MPOL_MF_DISCONTIG_OK)) { + if (!vma->vm_next && vma->vm_end < end) + return -EFAULT; + if (qp->prev && qp->prev->vm_end < vma->vm_start) + return -EFAULT; + } + + qp->prev = vma; + /* * Need check MPOL_MF_STRICT to return -EIO if possible * regardless of vma_migratable @@ -631,15 +641,6 @@ static int queue_pages_test_walk(unsigne if (vma->vm_start > start) start = vma->vm_start; - if (!(flags & MPOL_MF_DISCONTIG_OK)) { - if (!vma->vm_next && vma->vm_end < end) - return -EFAULT; - if (qp->prev && qp->prev->vm_end < vma->vm_start) - return -EFAULT; - } - - qp->prev = vma; - if (flags & MPOL_MF_LAZY) { /* Similar to task_numa_work, skip inaccessible VMAs */ if (!is_vm_hugetlb_page(vma) && _