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 46505CCF9EE for ; Wed, 29 Oct 2025 19:50:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A2AF68E00E4; Wed, 29 Oct 2025 15:50:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A029D8E00B2; Wed, 29 Oct 2025 15:50:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 93FB78E00E4; Wed, 29 Oct 2025 15:50:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 833AA8E00B2 for ; Wed, 29 Oct 2025 15:50:29 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 1C4DA12B41C for ; Wed, 29 Oct 2025 19:50:29 +0000 (UTC) X-FDA: 84052193778.14.A4E92FC Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf21.hostedemail.com (Postfix) with ESMTP id 7D1431C0014 for ; Wed, 29 Oct 2025 19:50:26 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=IaH0WiB+; spf=none (imf21.hostedemail.com: domain of rdunlap@infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=rdunlap@infradead.org; dmarc=pass (policy=none) header.from=infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1761767427; 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=ywMRa9td/qLYvz0QLFt/dHlJeUkQz4iWrYlNlCayuSE=; b=nDZXHCW4b2/y3VagzT7eyv5tjZXf086lSPQNBxnZsrLHKBEEyOLuefAykqGJbiPLIgRF2L 3jBE3TvHfsiEs8D6z2zKzH1/qu/GCvmuzivltd68Xoc/sJyEIbjtYWA+3uPxlqYN4/JM1c QZne8pvW3lBlzEW+Kh9KONsf/ivQU1w= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=IaH0WiB+; spf=none (imf21.hostedemail.com: domain of rdunlap@infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=rdunlap@infradead.org; dmarc=pass (policy=none) header.from=infradead.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1761767427; a=rsa-sha256; cv=none; b=UJQ+JerzHORVf9j3En65TgV8dfLbQqJNrOsPhGmpyh9AXJFQADG9x+c9pYRMitBwwm9YBC 5IdIZ2hSpY9f+J8TL6yDqsnE94Fm/xwWBLy2nVIE+fcjMpE0H59UrAE332CjPgScQjG3Ln l5j+GXmyCyY0/L7Gci/BFGiwM0KLBuQ= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Sender:Reply-To:Content-ID:Content-Description; bh=ywMRa9td/qLYvz0QLFt/dHlJeUkQz4iWrYlNlCayuSE=; b=IaH0WiB+Bb8bae/n25tIQisGQE EwhH0nUvAY0WF68tV+bqAjeM5vt1+TFM+p9SWhDN7SSKHd71InQaX+spzoIsKsfRnYzLiPymBfv8b G0YUSVRmmHR72tbVjz7S1JCp1h94cR+krcxjkfnjWvoj0qzTCwutfhbayHRtPzVCrp4DBQP6QMP7E /5l7sL8Z4TbLmfGLBzrYSVUcbZopibwGw10l95Xv2hyvw2OljCjZDfVaA7JzI0kxcTG+eF758lStl ZwIQstpTPU88RRMUCb5P0e0hsxC1roRLf9JTHYYZ9gSRvYXs7n8ZIZ62F6HWHDjILexzwXgNL7cbg SLWmox1g==; Received: from [50.53.43.113] (helo=[192.168.254.34]) by bombadil.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vECBX-00000002fGY-0vOJ; Wed, 29 Oct 2025 19:50:19 +0000 Message-ID: <6c273611-e815-4a4a-822d-f6e55cec3810@infradead.org> Date: Wed, 29 Oct 2025 12:50:18 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] mm: introduce VM_MAYBE_GUARD and make visible for guard regions To: Lorenzo Stoakes , Andrew Morton Cc: Jonathan Corbet , David Hildenbrand , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jann Horn , Pedro Falcato , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrei Vagin References: <7de40603015dee82970f5d37332a6d5af7532063.1761756437.git.lorenzo.stoakes@oracle.com> Content-Language: en-US From: Randy Dunlap In-Reply-To: <7de40603015dee82970f5d37332a6d5af7532063.1761756437.git.lorenzo.stoakes@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: wdk95qdonft8wq7zf7xm6ph9jqq6831g X-Rspamd-Queue-Id: 7D1431C0014 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1761767426-785192 X-HE-Meta: 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 VXOx1uoA Yv0mjTdnasiJsdjAxiQ1d14ecdqneVNG8f9Bgr9huHQMqdv+Mi5Kw/22hYYpTN30PE4yvdpV9liQvV6pVNaTogsM/g00lu56uoL2o+zAFGCzR/qDn45eD+Wdh7C87TkYXD+GMgJU/TfHP4Z8nhDfSa7+tCvUWKH1nW5YV4dCUD1Rrf7BFi/JMIfTf3SDVdI+AvL8K3hKpQGNwyrPqf7FbcmLrY1r489NBgwr+Q5qT4lHQVqguoAW7g6joiVvsERIjylBhu1wELGJdCF9XmoPVakxYKxdrQfMTCuA7jKsz+r6X4lur9neYFtPWWJZW6y5hlLzmSQFyliZbnW7hbjbE3lQJjp80rBcf60ZU1bErKw3evQnW5D+Rjk8DC95OJve1dhL/ 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 10/29/25 9:50 AM, Lorenzo Stoakes wrote: > diff --git a/mm/memory.c b/mm/memory.c > index 4c3a7e09a159..a2c79ee43d68 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1478,6 +1478,10 @@ vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) > if (src_vma->anon_vma) > return true; > > + /* Guard regions have momdified page tables that require copying. */ modified > + if (src_vma->vm_flags & VM_MAYBE_GUARD) > + return true; > + > /* > * Don't copy ptes where a page fault will fill them correctly. Fork > * becomes much lighter when there are big shared or private readonly -- ~Randy