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 02865CD5BAC for ; Thu, 21 May 2026 11:33:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5C2656B0088; Thu, 21 May 2026 07:33:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 573446B008A; Thu, 21 May 2026 07:33:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4890B6B008C; Thu, 21 May 2026 07:33:14 -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 3A2FE6B0088 for ; Thu, 21 May 2026 07:33:14 -0400 (EDT) Received: from smtpin15.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id DDE2E140621 for ; Thu, 21 May 2026 11:33:13 +0000 (UTC) X-FDA: 84791215866.15.D553D73 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf09.hostedemail.com (Postfix) with ESMTP id 580A114000F for ; Thu, 21 May 2026 11:33:12 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Y2i+qr0I; spf=pass (imf09.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@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=1779363192; 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=l+EoXkJOHHaMKKCSNNSB1HDpDEcGyHnosLWxzIMLQDk=; b=k2wVGi4A6EDvtG15j3FXebTBccMrCHeZd6omwI8NXF93KJIgZnYdaSeDF+HmkkPjV3CDpi G44hhF20dEsSjPGPahdLSqIA2GQjbswVgZqLMKOERBpBl+tJdskUkod5jugINQsZ0VFNLo tKy6tnqkisl4zjhlFxAFIT6Ikd5KO/c= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779363192; a=rsa-sha256; cv=none; b=pSnWvSQWCOMMPP6tDIwIs1PiB4Ah1NBnkSJu3x0CczrQuJFKT2MUUU/PnFkFJfr/XawGz9 S6O1p2rFiPUNSH/BtE+nISdCKFPoobXsZ4TSrgz+UaOG+K2XgsHqb/R9nHYBGR4SU0dCZW MEcGV+I203qzD/i52tAa9qSztQDnm68= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Y2i+qr0I; spf=pass (imf09.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id CB28860220; Thu, 21 May 2026 11:33:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 706261F000E9; Thu, 21 May 2026 11:33:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779363191; bh=l+EoXkJOHHaMKKCSNNSB1HDpDEcGyHnosLWxzIMLQDk=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Y2i+qr0IFNR9/uegvvo7AbfD9Oarz3B9H8p6zfxJGzUAAqZzObOfSM2BZnf57qqBX HoOjNKOtqiWqoX67EKvVQaSB0Ia3hipJvcxR0DxASYaKbjxetBC/9lv+UEGWGm0u0J QuPOkmXLjqQ504QovaC7JfqQBQ1GrbFuWl+Aenf7srOqM4tTYesj1FHPo41OuU0LVD ffbdDP52nLULIySYUXjHw4Y9lTO7my4eUepC6Zl4dAZjZ5ecAk8ChKC7YtQfC0MOyI CeGeYnoBZQ7ldi4QCvqphJMs9lz6m33rCDXLcl4ONUgZ5CMYdj7AKmF86I9YRaVvgk 7w0G3OY0Yinsg== Date: Thu, 21 May 2026 12:33:05 +0100 From: Lorenzo Stoakes To: Thorsten Blum Cc: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Andy Lutomirski , Thomas Gleixner , Vincenzo Frascino , Kees Cook , Andy Shevchenko , Yury Norov , David Laight , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/2] mm/vdso: make offset_in_page() usable without linux/mm.h Message-ID: References: <20260521090655.160282-4-thorsten.blum@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260521090655.160282-4-thorsten.blum@linux.dev> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 580A114000F X-Rspam-User: X-Stat-Signature: 4w95opommj9rn31coqsgw4rgq76sstnh X-HE-Tag: 1779363192-929792 X-HE-Meta: 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 VqlpXROr BLQSWrs+a47IhRP9f+qhK36wVtfiJ+ixGOVUhmgHgfUqmY4eZuNt3ok5g+cwkgBAiIvNJ/OLbUJq+HdG1cdIeOA8dymtKLslrHZZArpNKg8wy6XzrhKlI1Bfb1jbUXZ55ds0dtOPRrRNN+Q12ji5yFtX4Ov6/MA1wLNcOHR4GqVaI4t7VKt6aN66fm2dkLJ0cJvm5QF6RH1IQz2hCS8seE4aVqVfr/BIVD1/kYGFMJW7sQnhNITf1puTTHdPM6kpJZydtQHNAsNCNlauCEKbCRqhOXGZk6Z0JnDAdaXSBBQVCQwBmDa/IB/twYwIEggJ0IQ+qy5fGuMeBvA8WqnP6a4BCzkaAlOKkK07FK7usnwVhrPqGvNX8LL73jqy5OxNh39KbFktC3dzsy4QTUA2LrckZ6RmdmvRdmKs1 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, May 21, 2026 at 11:06:56AM +0200, Thorsten Blum wrote: > offset_in_page() is a small page-arithmetic helper that has been around > for 20+ years. However, page-offset calculations are still open-coded in > many places and in different ways: > > (unsigned long)p & ~PAGE_MASK > (unsigned long)p & (PAGE_SIZE - 1) > (long)p & (PAGE_SIZE - 1) > ... > > Some of these open-coded instances may be due to offset_in_page() being > buried 3000+ lines into linux/mm.h; others may have avoided including > linux/mm.h, which is a large header that pulls in many others. This is good but I think you're still missing the 'why' here (as to why files don't import mm.h, and thus what this series addreses), which presumably, is compile time. > > Patch 1 moves offset_in_page() from linux/mm.h to vdso/page.h, which > keeps the helper with other low-level page definitions and allows users > that only need offset_in_page() to avoid including linux/mm.h. > > Patch 2 shows a concrete example where including vdso/page.h is > sufficient and including the large linux/mm.h would be unnecessary. > > Existing users of offset_in_page() do not need to change because patch 1 > also includes vdso/page.h from linux/mm.h. > > This series is based on akpm/mm.git mm-nonmm-unstable commit > d067a83c8063 ("string: use min in sized_strscpy"), which is also in > linux-next. > > Changes in v2: > - Add a cover letter and drop the bytes_to_page_end() helper > - Move offset_in_page() to vdso/page.h as suggested by David and Lorenzo > - Use offset_in_page() in lib/string.c as an example since > bitmap_print_to_pagebuf() in lib/bitmap-str.c is being removed [1] > - v1: https://lore.kernel.org/lkml/20260517123428.1181981-4-thorsten.blum@linux.dev/ > > [1] https://lore.kernel.org/lkml/20260519163058.953690-3-ynorov@nvidia.com/ > --- > Thorsten Blum (2): > vdso: move offset_in_page() from linux/mm.h to vdso/page.h > string: use offset_in_page() in sized_strscpy() > > include/linux/mm.h | 2 +- > include/vdso/page.h | 2 ++ > lib/string.c | 3 ++- > 3 files changed, 5 insertions(+), 2 deletions(-) > > > base-commit: d067a83c8063d1bdcbd9af8e1326d846f85138b8