From patchwork Tue Dec 15 03:08:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11973777 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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 C5005C4361B for ; Tue, 15 Dec 2020 03:08:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6500522CB1 for ; Tue, 15 Dec 2020 03:08:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6500522CB1 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 03E596B00CB; Mon, 14 Dec 2020 22:08:25 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id F09248D0014; Mon, 14 Dec 2020 22:08:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E1FC88D0013; Mon, 14 Dec 2020 22:08:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0162.hostedemail.com [216.40.44.162]) by kanga.kvack.org (Postfix) with ESMTP id C77E86B00CB for ; Mon, 14 Dec 2020 22:08:24 -0500 (EST) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 980463631 for ; Tue, 15 Dec 2020 03:08:24 +0000 (UTC) X-FDA: 77594033328.12.seat54_1410c2f27420 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id 7B03518015104 for ; Tue, 15 Dec 2020 03:08:24 +0000 (UTC) X-HE-Tag: seat54_1410c2f27420 X-Filterd-Recvd-Size: 3992 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Tue, 15 Dec 2020 03:08:23 +0000 (UTC) Date: Mon, 14 Dec 2020 19:08:21 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1608001703; bh=6yeI54W6MW4NXm5Qm1URDF4jYYjXuDrkBSRoDB90qCo=; h=From:To:Subject:In-Reply-To:From; b=HWXi/1iz412fWsr9aZW5wLy1rYN6nlGUuSQnd7yWUCnEhTAYSoznIWL3iRvLqEeIm NukYqrTN3enieXMvx7RlVbKYU2eqqdBbnNAYIxzIpN9iOykLsXf+uIE7XME9C+imFk m7IWWcMlokI8+uU1lhCATynzwpPkv6o2DtendmCE= From: Andrew Morton To: akpm@linux-foundation.org, bgeffon@google.com, catalin.marinas@arm.com, dan.carpenter@oracle.com, dan.j.williams@intel.com, dave.jiang@intel.com, dima@arista.com, hughd@google.com, jgg@ziepe.ca, jhubbard@nvidia.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, linux@armlinux.org.uk, luto@kernel.org, mike.kravetz@oracle.com, minchan@kernel.org, mingo@redhat.com, mm-commits@vger.kernel.org, rcampbell@nvidia.com, tglx@linutronix.de, torvalds@linux-foundation.org, tsbogend@alpha.franken.de, vbabka@suse.cz, viro@zeniv.linux.org.uk, vishal.l.verma@intel.com, will@kernel.org Subject: [patch 088/200] mremap: check if it's possible to split original vma Message-ID: <20201215030821.oEVfuwJC4%akpm@linux-foundation.org> In-Reply-To: <20201214190237.a17b70ae14f129e2dca3d204@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: Dmitry Safonov Subject: mremap: check if it's possible to split original vma If original VMA can't be split at the desired address, do_munmap() will fail and leave both new-copied VMA and old VMA. De-facto it's MREMAP_DONTUNMAP behaviour, which is unexpected. Currently, it may fail such way for hugetlbfs and dax device mappings. Minimize such unpleasant situations to OOM by checking .may_split() before attempting to create a VMA copy. Link: https://lkml.kernel.org/r/20201013013416.390574-6-dima@arista.com Signed-off-by: Dmitry Safonov Cc: Alexander Viro Cc: Andy Lutomirski Cc: Brian Geffon Cc: Catalin Marinas Cc: Dan Carpenter Cc: Dan Williams Cc: Dave Jiang Cc: Hugh Dickins Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: John Hubbard Cc: "Kirill A. Shutemov" Cc: Mike Kravetz Cc: Minchan Kim Cc: Ralph Campbell Cc: Russell King Cc: Thomas Bogendoerfer Cc: Thomas Gleixner Cc: Vishal Verma Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton --- mm/mremap.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/mm/mremap.c~mremap-check-if-its-possible-to-split-original-vma +++ a/mm/mremap.c @@ -493,7 +493,7 @@ static unsigned long move_vma(struct vm_ unsigned long excess = 0; unsigned long hiwater_vm; int split = 0; - int err; + int err = 0; bool need_rmap_locks; /* @@ -503,6 +503,15 @@ static unsigned long move_vma(struct vm_ if (mm->map_count >= sysctl_max_map_count - 3) return -ENOMEM; + if (vma->vm_ops && vma->vm_ops->may_split) { + if (vma->vm_start != old_addr) + err = vma->vm_ops->may_split(vma, old_addr); + if (!err && vma->vm_end != old_addr + old_len) + err = vma->vm_ops->may_split(vma, old_addr + old_len); + if (err) + return err; + } + /* * Advise KSM to break any KSM pages in the area to be moved: * it would be confusing if they were to turn up at the new