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 DB1F8C9830C for ; Wed, 23 Sep 2026 13:06:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E0FC36B009B; Wed, 23 Sep 2026 09:06:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC0BE6B009D; Wed, 23 Sep 2026 09:06:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CD6486B009E; Wed, 23 Sep 2026 09:06:17 -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 AE74B6B009B for ; Wed, 23 Sep 2026 09:06:17 -0400 (EDT) Received: from smtpin03.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 26D6180410 for ; Wed, 23 Sep 2026 13:06:17 +0000 (UTC) X-FDA: 85245050394.03.C16D57A Received: from mail-dl2-f43.google.com (mail-dl2-f43.google.com [74.125.229.171]) by imf15.hostedemail.com (Postfix) with ESMTP id 467D4A0004 for ; Wed, 23 Sep 2026 13:06:15 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=Fw5Td87p; spf=pass (imf15.hostedemail.com: domain of jgg@ziepe.ca designates 74.125.229.171 as permitted sender) smtp.mailfrom=jgg@ziepe.ca; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790168775; 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=ih23spaVgrDHOFSey9aqnpQ7LFap1dWio/xJjG+h0zE=; b=0XEaQAhBPVI2cA6U7uc1BO5/lrQuU0g94HGGqfW8vxa4rXnCStS+YAVRUvT7vzMtX/VzN1 mUeB8dbK4SvL7LvD4l5UKr16qyt3r21PingrtLIXZ7wo7q4Osbq7epMtIwBeRoCuBL2y5d 1buUi3vMJhbduAsch5xgagxBFLY6JhE= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790168775; b=rR2Odilgrs1Ck7JkoPHeohUUAGvFyWueoV/ahQ+NDZSrZ1shoL/D8i0yYZInshXdJJ3H0h /G6iJAqO0jXWUgDzuibzm1orR7n1viykZQN1aq6XSKZMdFcn74P75Cwf4TPyuvpClZDxPe U/yLHQHejCPmx1C2p0QvVOaAkTz6Dyk= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=Fw5Td87p; spf=pass (imf15.hostedemail.com: domain of jgg@ziepe.ca designates 74.125.229.171 as permitted sender) smtp.mailfrom=jgg@ziepe.ca; dmarc=none Received: by mail-dl2-f43.google.com with SMTP id a92af1059eb24-142dce6e235so660270c88.1 for ; Wed, 23 Sep 2026 06:06:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1790168774; x=1790773574; darn=kvack.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=ih23spaVgrDHOFSey9aqnpQ7LFap1dWio/xJjG+h0zE=; b=Fw5Td87ptxI6/v7J1iKLANimJus8k0jgUldz5cFfBC5+JxQ3Giu1aMZfkPVc/1gN/R kbChTP01w3nRgX3bof0kb64Vib3fJ/WZGzsTOf9GuI6nek9D6GbKNPiwRbkgHkD4Buin XTIHDDMlRZ1tc9nysWXXEZVpzCsK9g7NtO0Rvldt6llkSwFi2KQhOaoWyLKM8BZPdSpD 8MMqa2vJqkzlggiOXmzIZvN+Lno7DIF0jdjMHeD+Vp77mLNlfkxbgykJ+EZH7c/BKHrb lGahpsJnol8Cj1yudRRO69EZmr9pcL2RTpdsIDDg97IHYvc9l5dAo1kkBi0qhT/zcEES YQ5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790168774; x=1790773574; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=ih23spaVgrDHOFSey9aqnpQ7LFap1dWio/xJjG+h0zE=; b=Dve6wm5gqImwQ9YIFvmSwFAXLY2eb2vDeGhaJT0OZxV6+W5bR7ssPeskH3uRvOmwhA xtA81dGTnhX4Y4yPSzNZndwVb24DbjN43RUD8j81YglfS0myWHHCty0rneTKAm0xaKMi c+lbtCSCdMXRAcfk7PZ+II3oiUNh38UumO7eZVPE3Vx8zcralzTID0DaYdUgJwPq4/61 dIOymx2qcI7l0F73oQJu+rf6FnTZIfkAWvrITPOjC1psWf1AuRKe2fu5rWpbFw+hqrpM +Q3+zayqV4UnAVxRqKN13XEA9S652hWP4R/xARTSrWAg7btawzo2xVBaAGzrQ7/tRNqy hiAQ== X-Forwarded-Encrypted: i=1; AKwUvBwH3ZrMqDRn3Y7WEx7WuJsC6tf0MmExkUdGfiuutMzrEUt5zQpCACjK/DrV3ko5r8AEhWRl7nn6jA==@kvack.org X-Gm-Message-State: AFuF++k2jiPs8f8xuczUfLMjaXCCYxaVBTUIme3agVHEaJraoRsajDwa jDnUzt/k2kfoJOjSWLHrfI44sd07kgGBPY/SKXsBD8bHA3UGLagz0hkWowkmH9qznSM= X-Gm-Gg: AYBFou0ZxqZMq6+g9VehpD8UHJYNdvGdz4pMX4eTKeenBu6PBc0pNhR9x0KcWLBT7bx tJ9NQKoO20utdll35txuH1HG2RCWzHQfK8geJ/ghLF7MLHFG+IjMK4mLWBlQeeouDe7SqY7U1iY 8i7CPmUGavQzz6Vdg+7VL+BtxPtiFEvp+uCUqPWQEAX+7ct3BLgtAEKVXbH0KvWeZ5EoQP6caCO +CO7s0UvJsfofOHIhEf8cJkZ55fOx4T+nUXX+u5+jgtymvjFGAsLEgDwfN+Vj56PutSyC3IQjhM 9sMyD1PnK6sVFLfS0JqdTWlUiBE6cy5vrC8mlgN3LHCoKGyhaBMLwEkId3sdukPP+1ZOiBpmJUX OW7czoz6hCT8D6oodrRkZv6iCvqAyPD195LPTTy6mtq6JUrckYW7mkBYBAJFfET7Kdlak9qwMJn DEcxKarlk6qlrY0y+MO39fYhOm+lQ3/KFu1+xSOMYc5Koo X-Received: by 2002:a05:7022:1402:b0:143:2719:566c with SMTP id a92af1059eb24-144f9198b49mr2872815c88.40.1790168773123; Wed, 23 Sep 2026 06:06:13 -0700 (PDT) Received: from ziepe.ca ([130.41.10.202]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-144f98a288esm10833873c88.13.2026.09.23.06.06.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 06:06:12 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1x9Mfr-0000000DZ6d-2NEP; Wed, 23 Sep 2026 10:06:11 -0300 Date: Wed, 23 Sep 2026 10:06:11 -0300 From: Jason Gunthorpe To: Catalin Marinas Cc: "Aneesh Kumar K.V" , linux-coco@lists.linux.dev, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, Andrew Morton , christian.koenig@amd.com, Joerg Roedel , Marc Zyngier , Marek Szyprowski , Robin Murphy , Steven Price , Sumit Semwal , Suzuki K Poulose , Thomas Gleixner , Will Deacon , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH v7 02/13] mm: Add an allocator for CoCo shared memory Message-ID: <20260923130611.GF1540250@ziepe.ca> References: <20260921144847.501151-1-aneesh.kumar@kernel.org> <20260921144847.501151-3-aneesh.kumar@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 467D4A0004 X-Stat-Signature: mnsnbm9431wz9p8awk7yedjy4wrhxj9o X-Rspam-User: X-HE-Tag: 1790168775-426937 X-HE-Meta: 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 zDuxNoGp DXgzikFFGVlcFKpeJewxZ1rjixBl9mT3ScMwzP6N3ohQahvelEDQJ9UC75qgpNKCGIlO5jhvPFMdL7WO0ZBKziJqZg2eQ0YWbxPhB1TS7Hi8rOUYy9iwsolRhFsOhQuVnH16sohqbWZvf36jQRCOxhnLTierEPh0YNh7sCR8EV0CxM0T+VaVrUkmVDXhL1UBclnSLpBqAwosuCeTKjn4X0QK0yJrm8QYe4SK+t9ITp1Ia8zrUJsrNYVCrF7ui/ylcugVS5C8I8TDk4TI5PJKui7HEm/0dDZSKs/Eu Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Sep 23, 2026 at 11:40:36AM +0100, Catalin Marinas wrote: > The simplest is probably to always zero in the backend and ignore > __GFP_ZERO to the allocator. But it's probably only marginally smaller > than passing a CC_SHARED_ZERO flag down. Get codex to try this as well > and compare the diffstat. For patch ordering I would convert to use the allocator first The semantics of the new API should be clear If you pass GFP_ZERO then the resulting allocated memory is zero Otherwise the allocator does Whatever The Arch Needs to not leak private data out. Once places are converted to the allocator lets go see what is left and ask why it is left and what API it actually needs. I think HCH was right that nobody should be calling this in driver code, lets aim to unexport set_memory_decrypted as an ideal goal Jason