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 3E676C44536 for ; Thu, 22 Jan 2026 11:22:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9ED6D6B0149; Thu, 22 Jan 2026 06:22:20 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 995E36B014B; Thu, 22 Jan 2026 06:22:20 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 87BED6B014C; Thu, 22 Jan 2026 06:22:20 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 72C8B6B0149 for ; Thu, 22 Jan 2026 06:22:20 -0500 (EST) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 15C3DD269D for ; Thu, 22 Jan 2026 11:22:20 +0000 (UTC) X-FDA: 84359361240.19.6BFECE7 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf23.hostedemail.com (Postfix) with ESMTP id 2A7AC140007 for ; Thu, 22 Jan 2026 11:22:18 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MtXcReft; spf=pass (imf23.hostedemail.com: domain of kas@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=kas@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1769080938; 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=Om/rZOQIDleSoDIbcI6IoE+evj8lKFQsByV4u3Cnfyo=; b=nvXHDgTkYtbo8LveT14zqXH5TV/0Is4gnY3a6C+HyrS0K8gt5y8+DE2PAOwVBAewgUa7xe x1TnQ3oEgLpnmBKoht3KsYgHVAzjC6RQEgjdMmS7Ii/gjrPgnD50a2RoXnT6/BR5vsJrnq efca+FX61hmbKmKMlXOPdveey3oqNt8= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MtXcReft; spf=pass (imf23.hostedemail.com: domain of kas@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=kas@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1769080938; a=rsa-sha256; cv=none; b=EMKnJZtaXQlAY+S+Sd4KtXdgUHVrggK1fSPayoGjubEusPyeLZY57332E30p5qhIXnlnzX eQqvFV0gKjajgYNaiJGuJNzBBlc3foBLg7PeLEJcBHj17Swn6ldfQL+K9n5qXp3KNS1ola XInm42uPD3Z8GcErCzkh+FBVtS+wgAs= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 37E85600C4; Thu, 22 Jan 2026 11:22:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8CA0DC116D0; Thu, 22 Jan 2026 11:22:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769080936; bh=jY+6Ux20wmAFYj3ZDCilg3Fqqbo+VmiY4n3Np5FgRm4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MtXcReftCdP2oFGE4OG0RTQX7Q5IiOPR0vhdBuwluNE3DUBS7ON9s+dbR7i3vzj4K 2oubCIx2+Epn4BMnF+OkT+UFOGySFI0cpWmqaiIbfvH5rppwjD6T8RKVfVcxceDOIn znjINksqDZ04a/gR6K4KcQjXwTm2StzZEk01WJVUmg1kvn1Y8UDGoBqNL4oH/GNIwR nq3EVklGNFPF1RmqRVUU+FlO+hVTGrVSynU5exqtt27aTc/PqemXl3PYRdo+f3/hN9 ibX2WrvEOi6VhsAhHyPv/olj5TTttldMggtLUJQCKnBcluUnqd3MQEaITxlZfzDOuy pI3wDL2CyptuQ== Received: from phl-compute-10.internal (phl-compute-10.internal [10.202.2.50]) by mailfauth.phl.internal (Postfix) with ESMTP id ACECAF40068; Thu, 22 Jan 2026 06:22:15 -0500 (EST) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-10.internal (MEProxy); Thu, 22 Jan 2026 06:22:15 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgddugeeitdefucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepmfhirhihlhcu ufhhuhhtshgvmhgruhcuoehkrghssehkvghrnhgvlhdrohhrgheqnecuggftrfgrthhtvg hrnhepueeijeeiffekheeffffftdekleefleehhfefhfduheejhedvffeluedvudefgfek necuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepkhhirh hilhhlodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdduieduudeivdeiheeh qddvkeeggeegjedvkedqkhgrsheppehkvghrnhgvlhdrohhrghesshhhuhhtvghmohhvrd hnrghmvgdpnhgspghrtghpthhtohepfeekpdhmohguvgepshhmthhpohhuthdprhgtphht thhopeiiihihsehnvhhiughirgdrtghomhdprhgtphhtthhopegrkhhpmheslhhinhhugi dqfhhouhhnuggrthhiohhnrdhorhhgpdhrtghpthhtohepmhhutghhuhhnrdhsohhnghes lhhinhhugidruggvvhdprhgtphhtthhopegurghvihgusehkvghrnhgvlhdrohhrghdprh gtphhtthhopeifihhllhihsehinhhfrhgruggvrggurdhorhhgpdhrtghpthhtohepuhhs rghmrggrrhhifheigedvsehgmhgrihhlrdgtohhmpdhrtghpthhtohepfhhvughlsehgoh hoghhlvgdrtghomhdprhgtphhtthhopehoshgrlhhvrgguohhrsehsuhhsvgdruggvpdhr tghpthhtoheprhhpphhtsehkvghrnhgvlhdrohhrgh X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 22 Jan 2026 06:22:13 -0500 (EST) Date: Thu, 22 Jan 2026 11:22:08 +0000 From: Kiryl Shutsemau To: Zi Yan Cc: Andrew Morton , Muchun Song , David Hildenbrand , Matthew Wilcox , Usama Arif , Frank van der Linden , Oscar Salvador , Mike Rapoport , Vlastimil Babka , Lorenzo Stoakes , Baoquan He , Michal Hocko , Johannes Weiner , Jonathan Corbet , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCHv4 07/14] mm/sparse: Check memmap alignment for compound_info_has_mask() Message-ID: References: <20260121162253.2216580-1-kas@kernel.org> <20260121162253.2216580-8-kas@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 86ageyn9scohbcdjahffjb6in1771toy X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 2A7AC140007 X-HE-Tag: 1769080938-772023 X-HE-Meta: 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 7bMHq4w9 0TzNsI6UeGP/omLVM6dMI1ROhtoseS3sDLPmrMsXvwovOvhsaxClJskW43Fyzeo0bOaMsFkreEUfu1vrc6VL6G+46dSYyD/p5/rEkg2EXHJe0zPgBPrQEd4lPvXPby5LVkFFKgYwg6/d0r0MUfvLBYCPru/f/eGo17NgiOJPzalBiGnQm408GaUFiXpaem5eYzUweisSDbh0qi3nPDGGtN6lk7thabyCrMVx5K/uSOgpKFp8sANufuWSza9H9qrHEdUZhm7fUWYLy+uhE8Y/v8zP8QCuRMePqJ2H4GNpOM8O4WEHRFjoiwKefIcvbxM1wr9/siGyn9w2QXkoCiFxMFX3q8NSAKqDq8K9o 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 Wed, Jan 21, 2026 at 12:58:36PM -0500, Zi Yan wrote: > On 21 Jan 2026, at 11:22, Kiryl Shutsemau wrote: > > > If page->compound_info encodes a mask, it is expected that memmap to be > > naturally aligned to the maximum folio size. > > > > Add a warning if it is not. > > > > A warning is sufficient as MAX_FOLIO_ORDER is very rarely used, so the > > kernel is still likely to be functional if this strict check fails. > > > > Signed-off-by: Kiryl Shutsemau > > --- > > include/linux/mmzone.h | 1 + > > mm/sparse.c | 5 +++++ > > 2 files changed, 6 insertions(+) > > > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > > index 390ce11b3765..7e4f69b9d760 100644 > > --- a/include/linux/mmzone.h > > +++ b/include/linux/mmzone.h > > @@ -91,6 +91,7 @@ > > #endif > > > > #define MAX_FOLIO_NR_PAGES (1UL << MAX_FOLIO_ORDER) > > +#define MAX_FOLIO_SIZE (PAGE_SIZE << MAX_FOLIO_ORDER) > > > > enum migratetype { > > MIGRATE_UNMOVABLE, > > diff --git a/mm/sparse.c b/mm/sparse.c > > index 17c50a6415c2..5f41a3edcc24 100644 > > --- a/mm/sparse.c > > +++ b/mm/sparse.c > > @@ -600,6 +600,11 @@ void __init sparse_init(void) > > BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section))); > > memblocks_present(); > > > > + if (compound_info_has_mask()) { > > + WARN_ON(!IS_ALIGNED((unsigned long)pfn_to_page(0), > > + MAX_FOLIO_SIZE / sizeof(struct page))); > > + } > > + > > 16GB is only possible in arm64 with 64KB base page. Would it be overkill > to align vmemmap to it unconditionally? Or how likely will this cause > false positive warning? CMA can give you 16GiB page on x86. -- Kiryl Shutsemau / Kirill A. Shutemov