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 A406FC61DC6 for ; Thu, 27 Aug 2026 11:18:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AD57D6B0096; Thu, 27 Aug 2026 07:18:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A867C6B0098; Thu, 27 Aug 2026 07:18:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 97AF36B0099; Thu, 27 Aug 2026 07:18:27 -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 7BBB76B0096 for ; Thu, 27 Aug 2026 07:18:27 -0400 (EDT) Received: from smtpin07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 0ABE91403CD for ; Thu, 27 Aug 2026 11:18:27 +0000 (UTC) X-FDA: 85146801054.07.A53E55D Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf17.hostedemail.com (Postfix) with ESMTP id 77E0C40005 for ; Thu, 27 Aug 2026 11:18:25 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=DC6qIxE0; spf=pass (imf17.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-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787829505; b=MC51qvwb+ucLyN5ZTfN/k+woBGB7ybJotNEbJg2NrVmPEfKsPBcu349NJy1bv9qBaSOEcw FeYgtZwy/z6su/213wDfShUCBNZ86NNllTDF2++5D36FFPbYS7JzzGe/8PDny1QFrN7XaY jQW7NZv3jBhb+pPpkGMmkIKToyIMaiU= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=DC6qIxE0; spf=pass (imf17.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=1787829505; 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=UXfBo8v3K8VIzDSO2VHXgtuPrAb/8lRFr7BXsf++oYA=; b=JRmKV3+Fa3a26lc18GYVlp44pSZUhs1Mb0l4xSpl5g4Ohb8H+fK/RfuWQMlf0/em5tkd9p zp6roPjiKfwCCkx/Xvwo15zcyPgFnUe4HpDwPU4ETg+IjRxVqawIN0fH7D1NMjwI+vkq5t mA4nX8qSKFeQFiXwaUJDHg0IL7JGYjo= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id DE061600D4; Thu, 27 Aug 2026 11:18:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 30FF01F000E9; Thu, 27 Aug 2026 11:18:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787829504; bh=UXfBo8v3K8VIzDSO2VHXgtuPrAb/8lRFr7BXsf++oYA=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=DC6qIxE0KrdRhnwTpQj+mqOREb/P52l2gDOdyFApoE8VA1gv3wcCC3cG1+ykL3FjI gLV3FcWtR1+Q8HXEsmNwdHlWMLmr6Ox5CZzzOTla/i+4zIByVE+n7H9QeLbqUQogTP HINaxGjyQ2EfkOvrIiHXrZQ/YuvaW1nAJ04hK9lO596nhxDAP9PBO+TTzqNAXyYD8y jFe48V+dIKFBme7rHsNveL4VaiDtgdVQ6BFNh0GS6CIQwxW+R8p1M0PGA1lY/0j4F/ kjvulu43FN0rQAskUM5hgMh93Jh6XhGXLIM5ckhruJrXivG8JmUlG0gU47N82N0yaF KlpeMGvJUSCAQ== Date: Thu, 27 Aug 2026 12:18:14 +0100 From: "Lorenzo Stoakes (ARM)" To: Mike Rapoport Cc: Andrew Morton , David Hildenbrand , Baolin Wang , Barry Song , Dev Jain , Hugh Dickins , Jann Horn , Jason Gunthorpe , John Hubbard , Jonathan Corbet , Lance Yang , "Liam R. Howlett" , Masami Hiramatsu , Mathieu Desnoyers , Michal Hocko , Muchun Song , Nico Pache , Oscar Salvador , Pedro Falcato , Peter Xu , Ryan Roberts , Shakeel Butt , Shuah Khan , Steven Rostedt , Suren Baghdasaryan , Usama Arif , Vlastimil Babka , Zi Yan , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH 6/6] userfaultfd: collapse VM_UFFD_{MISSING,WP,MINOR,RWP} into single VM_UFFD Message-ID: References: <20260823-uffd-vm-flags-v1-v1-0-3086981b33cf@kernel.org> <20260823-uffd-vm-flags-v1-v1-6-3086981b33cf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 77E0C40005 X-Stat-Signature: 168duf3arrxzgsfwrmgu1gqyuf8spgsa X-HE-Tag: 1787829505-862014 X-HE-Meta: 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 b6WsMaze Z8QycQOenvXDxUgJugHyaYifn869JONbP03rde/vJVAB0dbvp4J1WImY6qYJLS0nlg9BjXmg9Wzph+ViztOTkYXL2H5zkQD/1twDCmvlMDnn+9Dd+C9xbcVYAk0hqr5yJspHavKbMlUSHhDvSnn2uupw99g+7hedw431r5d24XYb5lwmi7McYRU5bbJu6BJrcJ39R24+LKS//PHgWVmVnKTnPLWKCD1a8rTJIgWejZFDIzdpHTfVzDkIex8R5/HlOtf+rewzhSz/Aa3Txh6awsjRIZNo+vyK1q8pGemYjlh2+bww= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Aug 27, 2026 at 12:16:32PM +0100, Lorenzo Stoakes (ARM) wrote: > So actually you're increasing by a cacheline and increasing the VMA size by > 64 bytes, i.e. 1/3, which is unacceptable obviously. > > Maybe there's something that can be done with: > > /* forced alignments: 1 */ > > Perhaps? But that looks potentially ugly. > I say elsewhere (or think I do) but to highlight - I think probably we could fix this by putting the flags in the low bits of vm_uffd_state.ctx? -- Cheers, Lorenzo