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=-7.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 60429C04EB8 for ; Thu, 6 Dec 2018 15:01:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24D7120850 for ; Thu, 6 Dec 2018 15:01:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544108464; bh=qrP4hft2aD+aiGucNN+SfC6hLUdlGoM4zPwCL2XMh7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2e86eBTX7nYswY1ObL5TSZn105M/1gMcGQlKULdGhbJGpELnpXZwjb+eOrQmpUug1 KGQB3UW/IRxbkA59n4f5QAGNh6pxZ0wgd0iANQYha+a2KE33YbwcfY/kICUbuGeSnf Y1kCi6wxj9i0bVWuzQgHbb1ZgDoOarpGjveyc/7c= DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 24D7120850 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726170AbeLFPBD (ORCPT ); Thu, 6 Dec 2018 10:01:03 -0500 Received: from mail.kernel.org ([198.145.29.99]:44484 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729935AbeLFOkY (ORCPT ); Thu, 6 Dec 2018 09:40:24 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (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 7E98C208E7; Thu, 6 Dec 2018 14:40:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544107224; bh=qrP4hft2aD+aiGucNN+SfC6hLUdlGoM4zPwCL2XMh7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VMqzyKC3OqUtTalf6LdBx4whgs+DwTZnUAn2DmhM9Brmus31/LslwdJT1CC0WBe2r otdmSnuMc+iEePkWBZ2TML1XZKfhqkGyU1igZ1J1E5yKQqzZXW/VaOOTnEzuzobw+P tHDZj+f21ZiyNtwb2ojeROh14aZz93PJG/oFF7lM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrea Arcangeli , Mike Rapoport , Hugh Dickins , Mike Kravetz , Jann Horn , Peter Xu , "Dr. David Alan Gilbert" , Andrew Morton , Linus Torvalds Subject: [PATCH 4.19 21/41] userfaultfd: use ENOENT instead of EFAULT if the atomic copy user fails Date: Thu, 6 Dec 2018 15:39:01 +0100 Message-Id: <20181206142951.554944815@linuxfoundation.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181206142949.757402551@linuxfoundation.org> References: <20181206142949.757402551@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrea Arcangeli commit 9e368259ad988356c4c95150fafd1a06af095d98 upstream. Patch series "userfaultfd shmem updates". Jann found two bugs in the userfaultfd shmem MAP_SHARED backend: the lack of the VM_MAYWRITE check and the lack of i_size checks. Then looking into the above we also fixed the MAP_PRIVATE case. Hugh by source review also found a data loss source if UFFDIO_COPY is used on shmem MAP_SHARED PROT_READ mappings (the production usages incidentally run with PROT_READ|PROT_WRITE, so the data loss couldn't happen in those production usages like with QEMU). The whole patchset is marked for stable. We verified QEMU postcopy live migration with guest running on shmem MAP_PRIVATE run as well as before after the fix of shmem MAP_PRIVATE. Regardless if it's shmem or hugetlbfs or MAP_PRIVATE or MAP_SHARED, QEMU unconditionally invokes a punch hole if the guest mapping is filebacked and a MADV_DONTNEED too (needed to get rid of the MAP_PRIVATE COWs and for the anon backend). This patch (of 5): We internally used EFAULT to communicate with the caller, switch to ENOENT, so EFAULT can be used as a non internal retval. Link: http://lkml.kernel.org/r/20181126173452.26955-2-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli Reviewed-by: Mike Rapoport Reviewed-by: Hugh Dickins Cc: Mike Kravetz Cc: Jann Horn Cc: Peter Xu Cc: "Dr. David Alan Gilbert" Cc: Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/hugetlb.c | 2 +- mm/shmem.c | 2 +- mm/userfaultfd.c | 6 +++--- 3 files changed, 5 insertions(+), 5 deletions(-) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4080,7 +4080,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_s /* fallback to copy_from_user outside mmap_sem */ if (unlikely(ret)) { - ret = -EFAULT; + ret = -ENOENT; *pagep = page; /* don't free the page */ goto out; --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2286,7 +2286,7 @@ static int shmem_mfill_atomic_pte(struct *pagep = page; shmem_inode_unacct_blocks(inode, 1); /* don't free the page */ - return -EFAULT; + return -ENOENT; } } else { /* mfill_zeropage_atomic */ clear_highpage(page); --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -48,7 +48,7 @@ static int mcopy_atomic_pte(struct mm_st /* fallback to copy_from_user outside mmap_sem */ if (unlikely(ret)) { - ret = -EFAULT; + ret = -ENOENT; *pagep = page; /* don't free the page */ goto out; @@ -275,7 +275,7 @@ retry: cond_resched(); - if (unlikely(err == -EFAULT)) { + if (unlikely(err == -ENOENT)) { up_read(&dst_mm->mmap_sem); BUG_ON(!page); @@ -527,7 +527,7 @@ retry: src_addr, &page, zeropage); cond_resched(); - if (unlikely(err == -EFAULT)) { + if (unlikely(err == -ENOENT)) { void *page_kaddr; up_read(&dst_mm->mmap_sem);