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 6B36BCFA747 for ; Fri, 21 Nov 2025 08:13:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A89696B0062; Fri, 21 Nov 2025 03:13:26 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A3B096B0096; Fri, 21 Nov 2025 03:13:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 977336B0099; Fri, 21 Nov 2025 03:13:26 -0500 (EST) 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 83CBC6B0062 for ; Fri, 21 Nov 2025 03:13:26 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id AAAFD4ECF9 for ; Fri, 21 Nov 2025 08:13:23 +0000 (UTC) X-FDA: 84133899486.12.BE6732C Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf03.hostedemail.com (Postfix) with ESMTP id 15BC620007 for ; Fri, 21 Nov 2025 08:13:21 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=uuy6ZZsm; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf03.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1763712802; a=rsa-sha256; cv=none; b=g+4eUCpKj2cANiAIZZc6LL/ImDx3Webq6mRRi5Ff24mAfUQ2azYNc1UVXh9kE7FNIfRhWf TQtQKQrU8XQns3SYJ7hzNq52sq6J9VzOurjFU5naHOGJiQekmptWCNYa5MxcBmnp0W0Y9w 9yPFFCjOVI41SEjH/VhidFUz8t+xXQ8= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=uuy6ZZsm; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf03.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1763712802; 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=wHkBL3sxG1p8CtoCQHRZbNA0MrGszKgzlq2ISKJ9yP0=; b=U0AktbdNXVDOJt++lI/aoTkloDUUEPdVflcVF8hZ5ckNKO13FnHu6ImuCtXYyvssKvYgIk EFlITaRNJQtfc7oDNVrGQiBzyEmOTwO9UC3o7Xh5J/rFqa1XDclqTCoaG9scghjnBpGjnt 9/E4WwLaSbb5pHJTm7xLmoLrwmeB5Jo= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id C319D40B1C; Fri, 21 Nov 2025 08:13:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9FDBDC4CEF1; Fri, 21 Nov 2025 08:13:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763712800; bh=r0SQs2L4kV96eXA5ek224oIHHwc4SCwPNdL4FqIG5OY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=uuy6ZZsm3vRhy+kugYgjzAQlddWYfxNhX4+quSyuFFSXDIE35/y8Xfa7pkuAm3W3P Hs+rhGykqMEBVZrYIQeM8/kAy7vJ9DAxCeADQx8twhMd4RiIm+4Tf95tMCKMd/NFk8 kxmakSAkknQHLWWvdpLlLh/EwLqYNg9H8OrACYUtQKCwxP4HpiJNSHAQt+uWLica13 bNlQmTvj9X589zKfVFdbMAbAHtxE+N+rdJLJRZ5Qo0Lc8lXFCmy3CeheVUnqO+o55w KgpjgUZjdUUDklxi8nNEZETSBc5ycZn5OGFJfeDyAM8nse4v4jFhX74KqH7OpNV08E Lkfiii9DKQ+EA== Message-ID: Date: Fri, 21 Nov 2025 09:13:15 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/mremap: allow VMAs with VM_DONTEXPAND|VM_PFNMAP when creating new mapping To: Lorenzo Stoakes , "Kasireddy, Vivek" Cc: "linux-mm@kvack.org" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Akihiko Odaki References: <20251120053546.2885836-1-vivek.kasireddy@intel.com> <976e9916-c949-4fa0-b92e-87f6841b5cbe@lucifer.local> <070dcd0f-ef77-4924-baf1-6c380bca192d@lucifer.local> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <070dcd0f-ef77-4924-baf1-6c380bca192d@lucifer.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 15BC620007 X-Stat-Signature: pz459wr5zcnoetprckafy31he6k7jewx X-HE-Tag: 1763712801-753842 X-HE-Meta: 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 6flRjudA 9bjuXLRwkuGS11G+kAfDx6GwJkE7/xpniroBg1dgRon2HHRY= 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: > > Another way round here might be to try to use userland to figure out the file > that a mapping belongs to via e.g. /proc/$pid/map_files, determine the > attributes from /proc/$pid/maps and then generate a new mmap() call with the > same properties. Right, if we could find some way to just obtain the file/fd we could just avoid mremap altogether. I recall that CRIU used something similar to obtain the fd of a MAP_SHARED|MAP_ANON mapping (anon shmem) VMA, but my memory is a bit vague on that one. -- Cheers David