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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 730A6CA0EFA for ; Thu, 21 Aug 2025 20:07:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A1E2A8E002E; Thu, 21 Aug 2025 16:07:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9CF318E0027; Thu, 21 Aug 2025 16:07:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8982F8E002E; Thu, 21 Aug 2025 16:07:38 -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 6ADF38E0027 for ; Thu, 21 Aug 2025 16:07:38 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 3594F140542 for ; Thu, 21 Aug 2025 20:07:38 +0000 (UTC) X-FDA: 83801849796.13.63803A6 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf09.hostedemail.com (Postfix) with ESMTP id EBFF4140003 for ; Thu, 21 Aug 2025 20:07:35 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=E5sl1wE1; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf09.hostedemail.com: domain of dhildenb@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=dhildenb@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1755806856; a=rsa-sha256; cv=none; b=chsst94vEr3qfD49ED0iCb2gRAPd9thxL155/m5GX1XXRvS4UoE6NxAgn8k3ked+isWX4S v2YcSwyLzcAlYvpI91oIL9LhaCXveTTH1N6bEVEcI1G2Hg11djAAreqZ9wvm5EwVUbcH7b OSL+K9KK/4dhcSmZhUm0e5LsCZrv4RI= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=E5sl1wE1; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf09.hostedemail.com: domain of dhildenb@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=dhildenb@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1755806856; 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=r/kmddABpvZJu5K+QD662cz6jOGE1r8xokeQdlRgepQ=; b=uLvcg7YbGmtOdJHMKhtoEE+d+o7Deinw1ZArEdG2Te2PozVqXQyjeGeEnKupF7Q7tYU7jd ZEHmHFl8cA5rZMly5D7a59kZCVh5L/SpPnHQWCPkn/vecUJiQD0XKfSs1fifxe+0+jdEIy MHjCkVCozgBkixEdkTWhk0d1DbOxYKQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1755806855; 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=r/kmddABpvZJu5K+QD662cz6jOGE1r8xokeQdlRgepQ=; b=E5sl1wE1CIsFxUa+wftRZxms6HR2vxmvN9JdZjJYNl0uTyOJx5CZ0nCloW0VrKdexTfYgZ N3+MiM0LTD0pGSt+G0DAUw0xS5VRBIWbGUtIJRjsSdrsQzmH7qeH3FwG7wtuUKGm6qW68O nSiCz60weTDbWZ1Z4QK1GAoMaZsCJY0= 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-126-HLYDp20kNV6Q4OLvxH1p9w-1; Thu, 21 Aug 2025 16:07:33 -0400 X-MC-Unique: HLYDp20kNV6Q4OLvxH1p9w-1 X-Mimecast-MFC-AGG-ID: HLYDp20kNV6Q4OLvxH1p9w_1755806853 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3b9dc566cb4so996111f8f.1 for ; Thu, 21 Aug 2025 13:07:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755806853; x=1756411653; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=r/kmddABpvZJu5K+QD662cz6jOGE1r8xokeQdlRgepQ=; b=asVrKj63I9NVjytluSWJebBTCauQhCvhklKTm/Jnt668c8gYPm0XXZfJqIySCq37FU ea5MQHuxCMpKzaRxPWfk3U0b1wK+qiHI5y+MwEKpUY9gAcrsxBVrkqzvPQ7z9sNQHPA9 1cZgmqS4AFbac0ilHazhvd9o1w9ZDuC6XN+XbjTzzQnaBWR3nW4MjmJff40XplAItjHk QAiRNZrM1RMs0oeX2brpEFJeSJXdRkg/ku9kha4ABOmtp2qNGMN9NKSGQGgILhUN/5Kd lTqr0iTjJS0BLZiNpHDF92e9aaW3HFPX5Ph/wy69GnpEQNN49ObviJzYE6bwOnF7Kz4x pUuA== X-Forwarded-Encrypted: i=1; AJvYcCXg29k7MeZBDiaBOCgMdTXkS/IY8aVKwR+JXAVWQkZVSIFl0VtSpp/dp+UaL4fIxTrhxmrgq9Ol5w==@kvack.org X-Gm-Message-State: AOJu0YzaxCXeLzFABEwhy4+NAPgsonmyktA2bp+OTj4bA+eqP015qW0I Ai6wcgaRmm8GXlQTvh5qqoT4Wewllm2UYRHMbmFE32bCWLT+TWaYTBzyH2hE9S+bjtMZgISwmEW Jwbqctv8ksNnjQWDHUDsgukfesSEHXSGtkDXlcXZDJw6RUt/ACWVz X-Gm-Gg: ASbGnctxscKYQhNkIvo+XgnPliMA0Ea+QVuwmH093VDBSI8vLmMgIRdNZR/9FksQ0dI PhtZ0WSB9EOhK/TiPuOaWvkzo8iiX7NqSld53zcPCIXbJ5DKXey1ZqDHO09zg83KOAbKmACTY2A cBjvEL+5USuOTRhd35NReVxRXBuB+pM0fYGeqNOzBfML5WQsqH4IImCMhKlIvlqdMrjWsste8uv 79TP7m7fVw6rFvpmGW+po13fO9GmrSGcL+cY+VbQZIGnnEJHLUSdqsTDGzcRMgNxcBnW583R/aZ blH+PXAVJKeqZtwhMVo3cB1z5sYPZm0btjhwwRSP2unjJfm+vyImnYCHK/ZNLMLHLwys6bJ7ejN rvtES9dwxl/tT5xedvIbHdA== X-Received: by 2002:a05:6000:2dc7:b0:3b9:15eb:6464 with SMTP id ffacd0b85a97d-3c5daefa9e0mr244704f8f.15.1755806852614; Thu, 21 Aug 2025 13:07:32 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHbqF8V2lF/CygktHxSJZNB7+pmyneW6nxhnLwTxWefpTwvecQ9FG1LkYH8lxi0WUYYPrMQFQ== X-Received: by 2002:a05:6000:2dc7:b0:3b9:15eb:6464 with SMTP id ffacd0b85a97d-3c5daefa9e0mr244660f8f.15.1755806852102; Thu, 21 Aug 2025 13:07:32 -0700 (PDT) Received: from localhost (p200300d82f26ba0008036ec5991806fd.dip0.t-ipconnect.de. [2003:d8:2f26:ba00:803:6ec5:9918:6fd]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-3c077789c92sm12629958f8f.52.2025.08.21.13.07.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Aug 2025 13:07:31 -0700 (PDT) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: David Hildenbrand , Alexander Potapenko , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , Dmitry Vyukov , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, iommu@lists.linux.dev, io-uring@vger.kernel.org, Jason Gunthorpe , Jens Axboe , Johannes Weiner , John Hubbard , kasan-dev@googlegroups.com, kvm@vger.kernel.org, "Liam R. Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marco Elver , Marek Szyprowski , Michal Hocko , Mike Rapoport , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan Subject: [PATCH RFC 09/35] mm/mm_init: make memmap_init_compound() look more like prep_compound_page() Date: Thu, 21 Aug 2025 22:06:35 +0200 Message-ID: <20250821200701.1329277-10-david@redhat.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250821200701.1329277-1-david@redhat.com> References: <20250821200701.1329277-1-david@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: UpEegFs2zkX8VTUpEZg2uhQfiWiFV47_VWW9pBxDpQs_1755806853 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: EBFF4140003 X-Stat-Signature: r1cox18hmm1xebugy41q6ngcbofyk475 X-HE-Tag: 1755806855-749303 X-HE-Meta: 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 GJTvAYtb 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 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: Grepping for "prep_compound_page" leaves on clueless how devdax gets its compound pages initialized. Let's add a comment that might help finding this open-coded prep_compound_page() initialization more easily. Further, let's be less smart about the ordering of initialization and just perform the prep_compound_head() call after all tail pages were initialized: just like prep_compound_page() does. No need for a lengthy comment then: again, just like prep_compound_page(). Note that prep_compound_head() already does initialize stuff in page[2] through prep_compound_head() that successive tail page initialization will overwrite: _deferred_list, and on 32bit _entire_mapcount and _pincount. Very likely 32bit does not apply, and likely nobody ever ends up testing whether the _deferred_list is empty. So it shouldn't be a fix at this point, but certainly something to clean up. Signed-off-by: David Hildenbrand --- mm/mm_init.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index 5c21b3af216b2..708466c5b2cc9 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1091,6 +1091,10 @@ static void __ref memmap_init_compound(struct page *head, unsigned long pfn, end_pfn = head_pfn + nr_pages; unsigned int order = pgmap->vmemmap_shift; + /* + * This is an open-coded prep_compound_page() whereby we avoid + * walking pages twice by initializing them in the same go. + */ __SetPageHead(head); for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) { struct page *page = pfn_to_page(pfn); @@ -1098,15 +1102,8 @@ static void __ref memmap_init_compound(struct page *head, __init_zone_device_page(page, pfn, zone_idx, nid, pgmap); prep_compound_tail(head, pfn - head_pfn); set_page_count(page, 0); - - /* - * The first tail page stores important compound page info. - * Call prep_compound_head() after the first tail page has - * been initialized, to not have the data overwritten. - */ - if (pfn == head_pfn + 1) - prep_compound_head(head, order); } + prep_compound_head(head, order); } void __ref memmap_init_zone_device(struct zone *zone, -- 2.50.1