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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AA0ADC433EF for ; Sun, 3 Jul 2022 22:43:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229484AbiGCWns (ORCPT ); Sun, 3 Jul 2022 18:43:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229447AbiGCWns (ORCPT ); Sun, 3 Jul 2022 18:43:48 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 081DED0; Sun, 3 Jul 2022 15:43:47 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id AB2F1B80CE6; Sun, 3 Jul 2022 22:43:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A582C341C6; Sun, 3 Jul 2022 22:43:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1656888224; bh=Hqm29/Kx3OmOFJ2j4cLrOBL1mTG//Hw0qPLVpXPmuzo=; h=Date:To:From:Subject:From; b=jT+URwEFWZqTrY79Vk7puv1Rdhn6ipyXZsSG+vmcX6BlVOKOOVgT/moX1UkHbzMI/ wnnLZggwqOSuOnG5SyJVup36TNSkWhJuL+46xg3AVRPPm+dqXmmPO986GkCkP48zG1 DOIzU+95fU7krcFOV8aeuge5CUvoudC8xL3K8fgg= Date: Sun, 03 Jul 2022 15:43:43 -0700 To: mm-commits@vger.kernel.org, stable@vger.kernel.org, peterx@redhat.com, hughd@google.com, axelrasmussen@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-userfaultfd-fix-uffdio_continue-on-fallocated-shmem-pages.patch removed from -mm tree Message-Id: <20220703224344.5A582C341C6@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm: userfaultfd: fix UFFDIO_CONTINUE on fallocated shmem pages has been removed from the -mm tree. Its filename was mm-userfaultfd-fix-uffdio_continue-on-fallocated-shmem-pages.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Axel Rasmussen Subject: mm: userfaultfd: fix UFFDIO_CONTINUE on fallocated shmem pages Date: Fri, 10 Jun 2022 10:38:12 -0700 When fallocate() is used on a shmem file, the pages we allocate can end up with !PageUptodate. Since UFFDIO_CONTINUE tries to find the existing page the user wants to map with SGP_READ, we would fail to find such a page, since shmem_getpage_gfp returns with a "NULL" pagep for SGP_READ if it discovers !PageUptodate. As a result, UFFDIO_CONTINUE returns -EFAULT, as it would do if the page wasn't found in the page cache at all. This isn't the intended behavior. UFFDIO_CONTINUE is just trying to find if a page exists, and doesn't care whether it still needs to be cleared or not. So, instead of SGP_READ, pass in SGP_NOALLOC. This is the same, except for one critical difference: in the !PageUptodate case, SGP_NOALLOC will clear the page and then return it. With this change, UFFDIO_CONTINUE works properly (succeeds) on a shmem file which has been fallocated, but otherwise not modified. Link: https://lkml.kernel.org/r/20220610173812.1768919-1-axelrasmussen@google.com Fixes: 153132571f02 ("userfaultfd/shmem: support UFFDIO_CONTINUE for shmem") Signed-off-by: Axel Rasmussen Acked-by: Peter Xu Cc: Hugh Dickins Cc: Signed-off-by: Andrew Morton --- mm/userfaultfd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/userfaultfd.c~mm-userfaultfd-fix-uffdio_continue-on-fallocated-shmem-pages +++ a/mm/userfaultfd.c @@ -246,7 +246,10 @@ static int mcontinue_atomic_pte(struct m struct page *page; int ret; - ret = shmem_getpage(inode, pgoff, &page, SGP_READ); + ret = shmem_getpage(inode, pgoff, &page, SGP_NOALLOC); + /* Our caller expects us to return -EFAULT if we failed to find page. */ + if (ret == -ENOENT) + ret = -EFAULT; if (ret) goto out; if (!page) { _ Patches currently in -mm which might be from axelrasmussen@google.com are selftests-vm-add-hugetlb_shared-userfaultfd-test-to-run_vmtestssh.patch userfaultfd-add-dev-userfaultfd-for-fine-grained-access-control.patch userfaultfd-selftests-modify-selftest-to-use-dev-userfaultfd.patch userfaultfd-update-documentation-to-describe-dev-userfaultfd.patch userfaultfd-selftests-make-dev-userfaultfd-testing-configurable.patch selftests-vm-add-dev-userfaultfd-test-cases-to-run_vmtestssh.patch