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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCD51C25B08 for ; Fri, 5 Aug 2022 18:57:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2D91A8E0001; Fri, 5 Aug 2022 14:57:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 261226B0072; Fri, 5 Aug 2022 14:57:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0B58C8E0001; Fri, 5 Aug 2022 14:57:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id EB9C06B0071 for ; Fri, 5 Aug 2022 14:57:07 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id B126BC17AC for ; Fri, 5 Aug 2022 18:57:07 +0000 (UTC) X-FDA: 79766446494.13.8989817 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf05.hostedemail.com (Postfix) with ESMTP id 1AA3110013A for ; Fri, 5 Aug 2022 18:57:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659725826; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=38HMOlpiHz3hAI7+jcYvoHMIUhKTjvFP/aWFO5JyZUs=; b=QWkAk6THJ71Sj76AnovuN3Q+vjwWrIsgM+UEqKe/olUvBZP4ESjzOMpfDHv14OpFArCSxS NAm2RArC2tFM8IP69lw7TH8CQWH4+wawT+jrlSgQ0fvqBzeXd1jfizHfNQ8OgRyEj/6/pl d1Cm7illPXXy4X1bhaxkpuTmggMn+Xo= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-14-srVT1X3RNyyI_siWBdimGA-1; Fri, 05 Aug 2022 14:57:03 -0400 X-MC-Unique: srVT1X3RNyyI_siWBdimGA-1 Received: by mail-wr1-f72.google.com with SMTP id i15-20020adfa50f000000b002207a6887b3so648266wrb.15 for ; Fri, 05 Aug 2022 11:57:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:subject:organization:from :references:cc:to:content-language:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc; bh=38HMOlpiHz3hAI7+jcYvoHMIUhKTjvFP/aWFO5JyZUs=; b=B8IDDshj3SP+HeKl5IqhTFEaDXtc4046GH3n8qeV6zSEcFvVUKVCy0cgOZoT8wQMjE pPX6KSaXRBkgb+DswW1bPFptQ0KXL6wvYgrGr11fdqL1/O0lL4+ae4Po3V9EOvhKVZLG OGVXGWJUJ1w6yV3aBHgR8LQYVYh5/hbY6/nu26FkktstxBlUYXoEuqShemxb4G6jiHpp lNJdaUQcd3WjtQ2qXxwJRXD44KX4Wtg32cbqkcCWDXISG6bHS6eM+p8hPkCaHYluecWN XhRQLSsrDnPvJX8wo8yA2VeiGCSUsRO/2FEK20OdaO4wqIcfUEuyWh8o93xFrXt0b9a6 Ta2g== X-Gm-Message-State: ACgBeo2TFfUYhtyuWUu5xRppkVvrvO67lAVqn26wmPKLWsLkZzlwPK5V L7noc6w6ryrayloT+pxKE/5nVjoJ/1TgvSLFR0HLcdatRjsDfSZbz4G1tUCK7GAHxgqVjQ2/6lx qO1QpzfPUJiE= X-Received: by 2002:a5d:5081:0:b0:220:6262:be0b with SMTP id a1-20020a5d5081000000b002206262be0bmr4863602wrt.228.1659725822067; Fri, 05 Aug 2022 11:57:02 -0700 (PDT) X-Google-Smtp-Source: AA6agR4KFDPpXTnLc9xcWmV5EbrjJoKCLSsWZAX9+Qv0fALjuvgGAb/bq9BvB7bwLwfeM2udXcmh0A== X-Received: by 2002:a5d:5081:0:b0:220:6262:be0b with SMTP id a1-20020a5d5081000000b002206262be0bmr4863590wrt.228.1659725821805; Fri, 05 Aug 2022 11:57:01 -0700 (PDT) Received: from ?IPV6:2003:cb:c706:fb00:f5c3:24b2:3d03:9d52? (p200300cbc706fb00f5c324b23d039d52.dip0.t-ipconnect.de. [2003:cb:c706:fb00:f5c3:24b2:3d03:9d52]) by smtp.gmail.com with ESMTPSA id b4-20020adff904000000b0021e9fafa601sm4458360wrr.22.2022.08.05.11.57.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Aug 2022 11:57:01 -0700 (PDT) Message-ID: <73050e64-e40f-0c94-be96-316d1e8d5f3b@redhat.com> Date: Fri, 5 Aug 2022 20:57:00 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 To: Mike Kravetz Cc: Peter Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Muchun Song , Peter Feiner , "Kirill A . Shutemov" , stable@vger.kernel.org References: <20220805110329.80540-1-david@redhat.com> <20220805110329.80540-2-david@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v1 1/2] mm/hugetlb: fix hugetlb not supporting write-notify In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659725827; a=rsa-sha256; cv=none; b=oojawdd1WTqtMW00UaBE7nkL6m8wHLfjVkuY4PaoxkQIv0btALRean7+ps5YGxZ8Xi0IIi 1G3867W5NXWQqReNG7sHR8YjRhGN06A9JFOAYnpsx/efu4w5hGMOvUPL6B6/ARkWkW3wRH nkpDs+SML2jVjdu/xMLDuFdpwcglVPE= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=QWkAk6TH; spf=pass (imf05.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659725827; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=38HMOlpiHz3hAI7+jcYvoHMIUhKTjvFP/aWFO5JyZUs=; b=1eF3nWjCAH0cZT08MyHxjBD4T6FrdoE+R8hoAAR6iGncZeqL/b0Qa1amFAiTTDn7zUyklx mhDKXuYTssD1m7WcimL4602kocX7eV6hzT3warX54FZPaldTZw4dkmoT9lBjxKvvs6u1O8 PHGgZT0MOAjTEO1fm8oxmZTN7m9wL6k= X-Stat-Signature: 4ncgs8ey6gjue5p58jqeof5gdkxtpjhg X-Rspamd-Queue-Id: 1AA3110013A Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=QWkAk6TH; spf=pass (imf05.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1659725825-820336 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: On 05.08.22 20:33, Mike Kravetz wrote: > On 08/05/22 20:25, David Hildenbrand wrote: >> On 05.08.22 20:23, Mike Kravetz wrote: >>> On 08/05/22 14:14, Peter Xu wrote: >>>> On Fri, Aug 05, 2022 at 01:03:28PM +0200, David Hildenbrand wrote: >>>>> diff --git a/mm/mmap.c b/mm/mmap.c >>>>> index 61e6135c54ef..462a6b0344ac 100644 >>>>> --- a/mm/mmap.c >>>>> +++ b/mm/mmap.c >>>>> @@ -1683,6 +1683,13 @@ int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) >>>>> if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) >>>>> return 0; >>>>> >>>>> + /* >>>>> + * Hugetlb does not require/support writenotify; especially, it does not >>>>> + * support softdirty tracking. >>>>> + */ >>>>> + if (is_vm_hugetlb_page(vma)) >>>>> + return 0; >>>> >>>> I'm kind of confused here.. you seems to be fixing up soft-dirty for >>>> hugetlb but here it's explicitly forbidden. >>>> >>>> Could you explain a bit more on why this patch is needed if (assume >>>> there'll be a working) patch 2 being provided? >>>> >>> >>> No comments on the patch, but ... >>> >>> Since it required little thought, I ran the test program on next-20220802 and >>> was surprised that the issue did not recreate. Even added a simple printk >>> to make sure we were getting into vma_wants_writenotify with a hugetlb vma. >>> We were. >> >> >> ... does your config have CONFIG_MEM_SOFT_DIRTY enabled? >> > > No, Duh! > > FYI - Some time back, I started looking at adding soft dirty support for > hugetlb mappings. I did not finish that work. But, I seem to recall > places where code was operating on hugetlb mappings when perhaps it should > not. > > Perhaps, it would also be good to just disable soft dirty for hugetlb at > the source? I thought about that as well. But I came to the conclusion that without patch #2, hugetlb VMAs cannot possibly support write-notify, so there is no need to bother in vma_wants_writenotify() at all. The "root" would be places where we clear VM_SOFTDIRTY. That should only be fs/proc/task_mmu.c:clear_refs_write() IIRC. So I don't particularly care, I consider this patch a bit cleaner and more generic, but I can adjust clear_refs_write() instead of there is a preference. -- Thanks, David / dhildenb