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 8CE21C5AD4C for ; Thu, 23 Nov 2023 19:37:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D6E136B0706; Thu, 23 Nov 2023 14:37:26 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D1F426B0708; Thu, 23 Nov 2023 14:37:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BBF026B070D; Thu, 23 Nov 2023 14:37:26 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id AA4B16B0706 for ; Thu, 23 Nov 2023 14:37:26 -0500 (EST) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 7EBBEB6E9D for ; Thu, 23 Nov 2023 19:37:26 +0000 (UTC) X-FDA: 81490228092.07.4F1A747 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf02.hostedemail.com (Postfix) with ESMTP id 78B928000C for ; Thu, 23 Nov 2023 19:37:24 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Tm9POf0V; spf=pass (imf02.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@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=1700768244; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=xmOn5+FX7gFongPnnuombqlFZm27jJX8g7knRz4U4Fc=; b=uHNGkKX4awbCxk+ed+oC555yxqtBJNG2Xe63pnPnbtH6E8bftIvI6Z7ZqcRYoIEE/ppFNR TPcKNcN8AfYiCMHDEK70R5DWD+vJ7btO59vC6T8LdcldHy8Ru8gbzHvnFDzt5/fgdKC2bR t29t2r171lL+B4KU19lVFlEQ1gKQNJc= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1700768244; a=rsa-sha256; cv=none; b=jb8IY+hUmQortHHU+N+rGFpRdKy3FBV4d2wWmFLY6cRjIw2yOck3lFh2S35uJBEbemfpcG Zo0DRmlJ1s3nk6vg638qN6l2KMxoxM8gHYWzNrhvoltAQXc3MYgdVF05NrVImv29ZcPajb lhfOlKa9jqR8XKQoLAIhciPsTdP6QLI= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Tm9POf0V; spf=pass (imf02.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700768243; 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=xmOn5+FX7gFongPnnuombqlFZm27jJX8g7knRz4U4Fc=; b=Tm9POf0VUvJ6IlPmwpWos+8bxsDPJVfUTvl4x3TYcJ4jwG28IFLi592SLP+yUPhgJgSnM3 2C1WRWXALzzPN2Ki0j5R/huaKYitO5MklpLHwjBNAPv64hBRko5tZa3JpwqqA6gxbJSXbl C86aQcBa718MeP6kHWYQ5EMfoonEIww= Received: from mail-oa1-f69.google.com (mail-oa1-f69.google.com [209.85.160.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-53-Xhbb0YLSOGCLjQniU1UM-g-1; Thu, 23 Nov 2023 14:37:22 -0500 X-MC-Unique: Xhbb0YLSOGCLjQniU1UM-g-1 Received: by mail-oa1-f69.google.com with SMTP id 586e51a60fabf-1f9efc41382so451fac.0 for ; Thu, 23 Nov 2023 11:37:22 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700768241; x=1701373041; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=xmOn5+FX7gFongPnnuombqlFZm27jJX8g7knRz4U4Fc=; b=c0nxxjTmuwpO2me91MdiQ6B1fm71YbTmWmikG5o6MNvlxnPNCesT+6wOukuKrk0o2+ +ya2fOaCe0S9dv9gppOkPc2T+L15jegZRNqNHXkyvpFJdpQi+9UblkENGxo1QQyTfSNG j9OyZOEUtvyvegrpvavNtFuAZMyKmgimBPB6CAfKX4vjWh7hSIxgzi2jPvaG8nudNIT9 ow/aJ778/1Lfm5SrdFdOuqfUkuR3IFnSXzayIfj+XzZt0XXzChtJCtVD/7OY/2X20xqw ykezfgozUvGrT0wQFZMDKami7EyO6aH2Hxt80KaDLzVLMGCYGxyfaxsSBNk4eN+sq4OC /4vg== X-Gm-Message-State: AOJu0Yy5ICHXYq4izAAT3FAQMj7KN3zcEsKOdk8yZ9HsCoWClNqutb2A 59iICg9LuyztrClzmYjwFTX2apF1va5ZZYwit9UZ2T85+Bvu+NNeB8UKjYFoV/M5i3mFt2et8Qm s9k6IrVu+O7c= X-Received: by 2002:a05:6870:d0a:b0:1f9:5346:2121 with SMTP id mk10-20020a0568700d0a00b001f953462121mr357559oab.4.1700768241736; Thu, 23 Nov 2023 11:37:21 -0800 (PST) X-Google-Smtp-Source: AGHT+IGkKmRMwIRaB3Ih9vdlTMJmgge2PoiF567J/ze233V1+FMKyortqkbCHa/MQ2E7l3VCDMjKhQ== X-Received: by 2002:a05:6870:d0a:b0:1f9:5346:2121 with SMTP id mk10-20020a0568700d0a00b001f953462121mr357535oab.4.1700768241485; Thu, 23 Nov 2023 11:37:21 -0800 (PST) Received: from x1n (cpe688f2e2cb7c3-cm688f2e2cb7c0.cpe.net.cable.rogers.com. [99.254.121.117]) by smtp.gmail.com with ESMTPSA id kd26-20020a05622a269a00b00421b14f7e7csm690038qtb.48.2023.11.23.11.37.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Nov 2023 11:37:21 -0800 (PST) Date: Thu, 23 Nov 2023 14:37:18 -0500 From: Peter Xu To: Christophe Leroy Cc: Christoph Hellwig , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Andrea Arcangeli , James Houghton , Lorenzo Stoakes , David Hildenbrand , Vlastimil Babka , John Hubbard , Yang Shi , Rik van Riel , Hugh Dickins , Matthew Wilcox , Jason Gunthorpe , Axel Rasmussen , "Kirill A . Shutemov" , Andrew Morton , "linuxppc-dev@lists.ozlabs.org" , Mike Rapoport , Mike Kravetz Subject: Re: [PATCH RFC 06/12] mm/gup: Drop folio_fast_pin_allowed() in hugepd processing Message-ID: References: <20231116012908.392077-1-peterx@redhat.com> <20231116012908.392077-7-peterx@redhat.com> <57be0ed0-f1d7-4583-9a5f-3ed7deb0ea97@csgroup.eu> MIME-Version: 1.0 In-Reply-To: <57be0ed0-f1d7-4583-9a5f-3ed7deb0ea97@csgroup.eu> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Queue-Id: 78B928000C X-Rspam-User: X-Stat-Signature: uoijczyzpbwthr45a1rmz8c7kitacj8q X-Rspamd-Server: rspam03 X-HE-Tag: 1700768244-815402 X-HE-Meta: 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 OKn8eL9x WA00GxK4Ki4BVec+JN4CRl+rvttmv/W1V0JR3flgsZY6tA0GB8YmYwgjls5d5wiCQIzhp4qfUGwkGxw5JRvLEY0seQvg2kIOZl6FCV79FUCxE7Ej0bsvlF01No7ribbILYOMuLRwFO96QrKtfzt2qzauVHn6U0bvTyWXFnVAMsJc0qQ4bK/rGCVrFJ/4AdLUpJW79RdcuQ2apoQqcOdLMGZ0zzRjd1g6W3/gzMBTFAZNYvE4jvI+aDV8wYjEqEWdtoTi7bQ0JambX5nSH+0jhrBBQh0RC2yL64FLEcC5Br7cWc3AuKVdat64WdIopg72svXj1Pz2/5v+VH6Fa85741PWjXtQTGzg55R/ewM96LSogjItz2C+oXltDftZNZQZ2wWcwrimRCsBpS0kZ4pi3Lm63MlXXauuTqFw71gEDgfyGNdst/n+Ng4+WiPjKqAkSaxbJB4lHZGlOJBM= 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: List-Subscribe: List-Unsubscribe: On Thu, Nov 23, 2023 at 06:22:33PM +0000, Christophe Leroy wrote: > > For fast-gup I think the hugepd code is in use, however for walk_page_* > > apis hugepd code shouldn't be reached iiuc as we have the hugetlb specific > > handling (walk_hugetlb_range()), so anything within walk_pgd_range() to hit > > a hugepd can be dead code to me (but note that this "dead code" is good > > stuff to me, if one would like to merge hugetlb instead into generic mm). > > Not sure what you mean here. What do you mean by "dead code" ? > A hugepage directory can be plugged at any page level, from PGD to PMD. > So the following bit in walk_pgd_range() is valid and not dead: > > if (is_hugepd(__hugepd(pgd_val(*pgd)))) > err = walk_hugepd_range((hugepd_t *)pgd, addr, next, walk, PGDIR_SHIFT); IMHO it boils down to the question on whether hugepd is only used in hugetlbfs. I think I already mentioned that above, but I can be more explicit; what I see is that from higher stack in __walk_page_range(): if (is_vm_hugetlb_page(vma)) { if (ops->hugetlb_entry) err = walk_hugetlb_range(start, end, walk); } else err = walk_pgd_range(start, end, walk); It means to me as long as the vma is hugetlb, it'll not trigger any code in walk_pgd_range(), but only walk_hugetlb_range(). Do you perhaps mean hugepd is used outside hugetlbfs? Thanks, -- Peter Xu