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 C6BD2EB64D7 for ; Mon, 26 Jun 2023 08:06:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 21D988D0002; Mon, 26 Jun 2023 04:06:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1CCE58D0001; Mon, 26 Jun 2023 04:06:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 06E8D8D0002; Mon, 26 Jun 2023 04:06:36 -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 E836F8D0001 for ; Mon, 26 Jun 2023 04:06:35 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 62E6D160619 for ; Mon, 26 Jun 2023 08:06:35 +0000 (UTC) X-FDA: 80944167150.04.ABB1081 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf06.hostedemail.com (Postfix) with ESMTP id 33B87180016 for ; Mon, 26 Jun 2023 08:06:31 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=fseRFZ2Y; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf06.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1687766792; 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=bdy6ilB9MCEHjnSXB3UxFLYarjo26SKIUeQi/Jp98Ng=; b=aeAs+WXa8X/qSCN8C33pciHRr17s36zrs5IMLGf3PPr6JlliXxofYNXghS81nSuC65DHyD 2cFMjaNbwsadi9r9rpAzmbCR0GpTbLcqnfLQKSZXBouEeerT8F81T4TWp+1qsSgpoodGYI RQbJmiUwME70EFROBEPdOBeHyig2vMs= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=fseRFZ2Y; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf06.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1687766792; a=rsa-sha256; cv=none; b=LVRXxqT68QFuWPkHCRUL+vZJ40o4QiMna/B4ix321hcp1hfusXmNj1eXj/U4dqs+UtRbkf ebrTQ1EIvuObdAaVBy0Y0SU+GxqZzFT7SyoMktLGCpQnkQfVHrcue30oYheIb8aJ4NGt0N urG1BoaoN6AdcU8lgwt/9fjXWnsv0HU= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1687766791; 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=bdy6ilB9MCEHjnSXB3UxFLYarjo26SKIUeQi/Jp98Ng=; b=fseRFZ2Y1C86eQ4Ycewy0oPh723ulsVvm8pgKTZWC5KH08TabAuhac1yZJB/BUeBuVJZZE S4PHbwBXCD1PiR2pbGOYvngX9sJxsEK76m3A18b3SoHZWITy6poSkI+frJpx0KKPv7cIjA K0591gMt08R7+Uh7r/dGVMCV2FX8VuQ= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-590-Vx_T-foINXGPaod82i2sHA-1; Mon, 26 Jun 2023 04:06:27 -0400 X-MC-Unique: Vx_T-foINXGPaod82i2sHA-1 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-313e6020882so542080f8f.1 for ; Mon, 26 Jun 2023 01:06:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687766786; x=1690358786; 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:subject:date:message-id :reply-to; bh=bdy6ilB9MCEHjnSXB3UxFLYarjo26SKIUeQi/Jp98Ng=; b=Tv1HMalLXI+dcpm1O52grBz2EQwclBvbAhBqKu7w9LfnlRpUGk//TB0D1oTlmSkhrg joB+bBI1R7q6cK2S4cDNmN43AYR20pFULO6X70y8WFQAEIQy1fsZaRhcfV4eALttvEwJ nezg+xfVFFphTNrg/RwMj8EFALTKuB1qoM6EZZMVc9C8A+Uk1t5HCmzBZ12vh8GruxtR ZYNs6QDCz7ve/5crHtnaKiJJ8TMrzPC0dbawy81zIO9l5CUM6fKCUCNa4N7FiwAfTkUI nbCjKJJulWkEjooR+zIH7K7lgjkPsOdmptp93tbrHSw4BotmQKhuyo7EPdsQiEIOGuUn b1QQ== X-Gm-Message-State: AC+VfDxAu5ftyNenJTzeJKNZBXmpmeCHRsKR9gPEamYCSdhriIq4hJMG 8AxxyzCXky49B6kuwz//EV6oCZWrm6g3QV4gutrx/1xadj3uF6Q92uj5UdCZoDGEC6CGM2RMqb3 1Enrg+EfGRW4= X-Received: by 2002:a5d:5507:0:b0:313:e5ca:7517 with SMTP id b7-20020a5d5507000000b00313e5ca7517mr4774734wrv.9.1687766786193; Mon, 26 Jun 2023 01:06:26 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ76umJhgn/Hm6w0c6df0Vzwzqxxov5wQMyiuFZk9tAwcFYpmaRyYFJYCRhnVdFCT+eZjeiL5Q== X-Received: by 2002:a5d:5507:0:b0:313:e5ca:7517 with SMTP id b7-20020a5d5507000000b00313e5ca7517mr4774703wrv.9.1687766785754; Mon, 26 Jun 2023 01:06:25 -0700 (PDT) Received: from ?IPV6:2003:cb:c74b:7300:2ef6:6cd6:703c:e498? (p200300cbc74b73002ef66cd6703ce498.dip0.t-ipconnect.de. [2003:cb:c74b:7300:2ef6:6cd6:703c:e498]) by smtp.gmail.com with ESMTPSA id l6-20020a5d4106000000b0030c2e3c7fb3sm6559048wrp.101.2023.06.26.01.06.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Jun 2023 01:06:25 -0700 (PDT) Message-ID: <89fee4bf-29a1-db19-e0ae-dd827d277504@redhat.com> Date: Mon, 26 Jun 2023 10:06:24 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 To: Peter Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Lorenzo Stoakes , John Hubbard , Andrew Morton , Mike Rapoport , Yang Shi , Andrea Arcangeli , Vlastimil Babka , "Kirill A . Shutemov" , James Houghton , Matthew Wilcox , Mike Kravetz , Hugh Dickins , Jason Gunthorpe References: <20230623142936.268456-1-peterx@redhat.com> <20230623142936.268456-3-peterx@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v3 2/8] mm/hugetlb: Prepare hugetlb_follow_page_mask() for FOLL_PIN In-Reply-To: <20230623142936.268456-3-peterx@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 33B87180016 X-Stat-Signature: g457k6hy9n3pognzp8zajuiifdhmx548 X-Rspam-User: X-HE-Tag: 1687766791-429722 X-HE-Meta: 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 37nSgfGF VoMCykrbjBACpZTgn4SFVWNZjOYkWYJksrPOPZBi/U95Pwl1NvOIR7yN3LAi+ZFnQ5b0HDwq8iUCCJ68in5zJIBQjJFHePVYCyCrTbDSmwhq9F1b6bxjMKfNOhL5Nm+bq8szxfoLKAgJS0GFC760+frF2s9wmX3bTBsmldDPgyDbYj7RkLt5aaBc9+GeXXrpUsUsPDcu4s4PbniSRNbSU2N5nyj3j+xRfOq65P7PNKIBogjtbgUXGtMpaoP3raDxyORprwNoMqz85+PHnywRPUGuVbtP731uLuqSdfGlfvA0ZiH5+eOTaKgewjWdrpEItJ/penGxPJ9scNpf+RCK2sxmvHBu+XWt/VVscrMBcBZryuocacl4o5MGIKvC7w43d+/fjvitQjNYB81ngj9BAfHdSDAZtGFArC8UjJCb9AxzIgJlB8t7/pCHIgzEMk3Bmw4afpX1OL8avqT6c+lX5aOIW70/hCSs/SZ0m 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 23.06.23 16:29, Peter Xu wrote: > follow_page() doesn't use FOLL_PIN, meanwhile hugetlb seems to not be the > target of FOLL_WRITE either. However add the checks. > > Namely, either the need to CoW due to missing write bit, or proper > unsharing on !AnonExclusive pages over R/O pins to reject the follow page. > That brings this function closer to follow_hugetlb_page(). > > So we don't care before, and also for now. But we'll care if we switch > over slow-gup to use hugetlb_follow_page_mask(). We'll also care when to > return -EMLINK properly, as that's the gup internal api to mean "we should > unshare". Not really needed for follow page path, though. > > When at it, switching the try_grab_page() to use WARN_ON_ONCE(), to be > clear that it just should never fail. When error happens, instead of > setting page==NULL, capture the errno instead. > > Reviewed-by: Mike Kravetz > Signed-off-by: Peter Xu > --- > mm/hugetlb.c | 31 ++++++++++++++++++++----------- > 1 file changed, 20 insertions(+), 11 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index f75f5e78ff0b..27367edf5c72 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -6462,13 +6462,7 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, > struct page *page = NULL; > spinlock_t *ptl; > pte_t *pte, entry; > - > - /* > - * FOLL_PIN is not supported for follow_page(). Ordinary GUP goes via > - * follow_hugetlb_page(). > - */ > - if (WARN_ON_ONCE(flags & FOLL_PIN)) > - return NULL; > + int ret; > > hugetlb_vma_lock_read(vma); > pte = hugetlb_walk(vma, haddr, huge_page_size(h)); > @@ -6478,8 +6472,21 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, > ptl = huge_pte_lock(h, mm, pte); > entry = huge_ptep_get(pte); > if (pte_present(entry)) { > - page = pte_page(entry) + > - ((address & ~huge_page_mask(h)) >> PAGE_SHIFT); > + page = pte_page(entry); > + > + if ((flags & FOLL_WRITE) && !huge_pte_write(entry)) { > + page = NULL; > + goto out; > + } > + > + if (gup_must_unshare(vma, flags, page)) { > + /* Tell the caller to do unsharing */ > + page = ERR_PTR(-EMLINK); > + goto out; > + } No need to check if the page is writable (like all other callers and as gup_must_unshare() documents -- "for which pages that are write-protected in the page table") if (!huge_pte_write(entry) && gup_must_unshare(vma, flags, page)) { With that Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb