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 3C98EC433EF for ; Mon, 9 May 2022 16:41:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239246AbiEIQps (ORCPT ); Mon, 9 May 2022 12:45:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239245AbiEIQpo (ORCPT ); Mon, 9 May 2022 12:45:44 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E8BA71C197A for ; Mon, 9 May 2022 09:41:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652114505; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=46wpjVCZhJPBmgWeRQ9uBt+Od81o8qIGqdyqzSCTbIU=; b=JeETDsMEypPXoCbhMDCa+O3IBoSCrTKGO0VF+qyxMrTnCd+PRERsIAnsnFww2ERFkTskcE jOX/3TfEjfJgImkU0e7Je6ySx8psTtD68Q+v1sW3ahycrUrerv1+H7xdinh7T8hGnEcuaI RYVZdm0CK6tq2y4UTmGRzdmIauP7d8c= Received: from mail-io1-f69.google.com (mail-io1-f69.google.com [209.85.166.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-287-SNh7zupKPQytjE0ouUrrVQ-1; Mon, 09 May 2022 12:41:43 -0400 X-MC-Unique: SNh7zupKPQytjE0ouUrrVQ-1 Received: by mail-io1-f69.google.com with SMTP id d7-20020a0566022d4700b0065aa0c91f27so10299646iow.14 for ; Mon, 09 May 2022 09:41:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=46wpjVCZhJPBmgWeRQ9uBt+Od81o8qIGqdyqzSCTbIU=; b=dDzx3uI2hAF/RZ44YQq+u9D1I4Lde5gnPXsWZP157ZT3QlFYPFs90+nf2nlBnPVC3j VtFdz3LUOeKEVDJY34ky9r/T56/KK+8SZxGhiTqLT7++7+hXIVvX5I3y8szk177r3Lfh aC6p4DlE5ZmU99PhNlcgUmEP/Ew0HPCnWLGeFyk+FHqY/uxjyIdiv8sW2HMvJVdfRMyI E874zVo3G/ZAVh9uAMTTtxWfwQTjdwitm++daUCDTwOfHQ0Py1V4e4q8e2zcOJp6gVG+ GQfs/8AojtoNgaxt0D2OI72MJFWrCPAcR78Ric1woN9uMdPUVKfdcE5e8Jx9WxwQwh4y fHeQ== X-Gm-Message-State: AOAM533qJOXCbtQUrXycjvxjAWGSXltcdPnI35mgEPI+Jz/miqXlVUnm jzy3hSMCsvjmfjEul8TWPHfjLaY86h5FHglUY9HZX+vAyXAKS+vM7RAMHhg9zispPl1+xZPqOzK fFkyQNpDTBzDkCuoubkXgUCGA X-Received: by 2002:a05:6e02:164e:b0:2cf:82bc:6c76 with SMTP id v14-20020a056e02164e00b002cf82bc6c76mr6451762ilu.95.1652114503274; Mon, 09 May 2022 09:41:43 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxE3U4JsTh97DMqQwaSKR+J9MOnj5nTpGNATaHacf1CibJGqYaNUSWSiHqNy5VvKai+5PTu/Q== X-Received: by 2002:a05:6e02:164e:b0:2cf:82bc:6c76 with SMTP id v14-20020a056e02164e00b002cf82bc6c76mr6451741ilu.95.1652114503011; Mon, 09 May 2022 09:41:43 -0700 (PDT) Received: from xz-m1.local (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id x26-20020a6bfe1a000000b0065a48a57f6dsm3633311ioh.40.2022.05.09.09.41.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 May 2022 09:41:42 -0700 (PDT) Date: Mon, 9 May 2022 12:41:38 -0400 From: Peter Xu To: Mike Kravetz Cc: Gerald Schaefer , Baolin Wang , akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org, tsbogend@alpha.franken.de, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping Message-ID: References: <20220429220214.4cfc5539@thinkpad> <20220502160232.589a6111@thinkpad> <48a05075-a323-e7f1-9e99-6c0d106eb2cb@linux.alibaba.com> <20220503120343.6264e126@thinkpad> <927dfbf4-c899-b88a-4d58-36a637d611f9@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <927dfbf4-c899-b88a-4d58-36a637d611f9@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 06, 2022 at 12:07:13PM -0700, Mike Kravetz wrote: > On 5/3/22 03:03, Gerald Schaefer wrote: > > On Tue, 3 May 2022 10:19:46 +0800 > > Baolin Wang wrote: > >> On 5/2/2022 10:02 PM, Gerald Schaefer wrote: [...] > >> Please see previous code, we'll use the original pte value to check if > >> it is uffd-wp armed, and if need to mark it dirty though the hugetlbfs > >> is set noop_dirty_folio(). > >> > >> pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval); > > > > Uh, ok, that wouldn't work on s390, but we also don't have > > CONFIG_PTE_MARKER_UFFD_WP / HAVE_ARCH_USERFAULTFD_WP set, so > > I guess we will be fine (for now). > > > > Still, I find it a bit unsettling that pte_install_uffd_wp_if_needed() > > would work on a potential hugetlb *pte, directly de-referencing it > > instead of using huge_ptep_get(). > > > > The !pte_none(*pte) check at the beginning would be broken in the > > hugetlb case for s390 (not sure about other archs, but I think s390 > > might be the only exception strictly requiring huge_ptep_get() > > for de-referencing hugetlb *pte pointers). We could have used is_vm_hugetlb_page(vma) within the helper so as to properly use either generic pte or hugetlb version of pte fetching. We may want to conditionally do set_[huge_]pte_at() too at the end. I could prepare a patch for that even if it's not really anything urgently needed. I assume that won't need to block this patchset since we need the pteval for pte_dirty() check anyway and uffd-wp definitely needs it too. Thanks, -- Peter Xu