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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72D3ECCA48A for ; Mon, 25 Jul 2022 18:49:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 288B58E0001; Mon, 25 Jul 2022 14:49:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1CFAA8E0002; Mon, 25 Jul 2022 14:49:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E44708E0001; Mon, 25 Jul 2022 14:49:56 -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 C8559900002 for ; Mon, 25 Jul 2022 14:49:56 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id A0222A0641 for ; Mon, 25 Jul 2022 18:49:56 +0000 (UTC) X-FDA: 79726511592.19.E07C1C7 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf18.hostedemail.com (Postfix) with ESMTP id 2FB401C00AF for ; Mon, 25 Jul 2022 18:49:56 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5385C60DDD; Mon, 25 Jul 2022 18:49:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 686B2C341C6; Mon, 25 Jul 2022 18:49:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1658774994; bh=yy7PhlLUKJkcq1UG9oO0Tr3lq0L1Ce6BUI/PYbQQgRo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=EpLK5ir3x2pygWPzrF3kLbN2nReaDv3uYYmQ6nsUBxFdeFzVQtgrYgiwoW6BsNdrf NeRFRqWIi66kG44kByH3ilf/PkuTAIBkFcQxsCIvzyPJYepGv/wdagaSkGgZ1iwpKm 5stAXvjSfBT/22EGMUvr/Ff/oer0qL3+Z+YEelng= Date: Mon, 25 Jul 2022 11:49:53 -0700 From: Andrew Morton To: Ralph Campbell Cc: , Felix Kuehling , Philip Yang , Alistair Popple , Jason Gunthorpe , Subject: Re: [PATCH] mm/hmm: fault non-owner device private entries Message-Id: <20220725114953.7e53ca4b296e0e753ca7bfda@linux-foundation.org> In-Reply-To: <20220722225632.4101276-1-rcampbell@nvidia.com> References: <20220722225632.4101276-1-rcampbell@nvidia.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=EpLK5ir3; spf=pass (imf18.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1658774996; 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=yy7PhlLUKJkcq1UG9oO0Tr3lq0L1Ce6BUI/PYbQQgRo=; b=bmobLnlixwEg46wFmyIHLWC/7o+iCQbkzGydzTI6TahINXCQQRNZ6/spfRQK7DlKnIv/Dd WnuKhf1ppfAoV0ABdwe44vngYdaAqurwQfdM/JLMlWlk2K4pVZ2emJYhvnmjtXDakH5Thw zU/KUB6OzitTLX2B0wohy2Xxx+qAfYE= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1658774996; a=rsa-sha256; cv=none; b=jmyvAAQfKx3+sJd5uzQVXAdEsi+vyDTqNjFIWwPW9i9bjyQvGH4ZJYef/bMDQd0ZwB7GLn DR17uqsPfCfShWNX78EPXU0T6YpB5atGYKs1BlHZWCY7pHBWIAyZYTXR2s+o6P9B+/Naxr Ja60qpcSgmT54MFUXlvWZNSQ08lnce8= Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=EpLK5ir3; spf=pass (imf18.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspam-User: X-Stat-Signature: 3h8bibasgrf77y46spgtqtqgw85yterw X-Rspamd-Queue-Id: 2FB401C00AF X-Rspamd-Server: rspam02 X-HE-Tag: 1658774996-367052 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: On Fri, 22 Jul 2022 15:56:32 -0700 Ralph Campbell wrote: > If hmm_range_fault() is called with the HMM_PFN_REQ_FAULT flag and a > device private PTE is found, the hmm_range::dev_private_owner page is > used to determine if the device private page should not be faulted in. > However, if the device private page is not owned by the caller, > hmm_range_fault() returns an error instead of calling migrate_to_ram() > to fault in the page. Could we please include here a description of the end-user visible effects of the bug? > Cc: stable@vger.kernel.org Especially when proposing a -stable backport.