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 4215ED2E9DC for ; Mon, 11 Nov 2024 11:31:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B95376B0085; Mon, 11 Nov 2024 06:31:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B45BE6B0088; Mon, 11 Nov 2024 06:31:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A347C6B0089; Mon, 11 Nov 2024 06:31:29 -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 855D46B0085 for ; Mon, 11 Nov 2024 06:31:29 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 27118AB22E for ; Mon, 11 Nov 2024 11:31:29 +0000 (UTC) X-FDA: 82773598320.29.CC6E0A9 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) by imf08.hostedemail.com (Postfix) with ESMTP id 99D3C16001A for ; Mon, 11 Nov 2024 11:30:59 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=none; spf=pass (imf08.hostedemail.com: domain of linyunsheng@huawei.com designates 45.249.212.191 as permitted sender) smtp.mailfrom=linyunsheng@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1731324633; 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; bh=byaw+dvdLr6SBDgp7KIpdiIjwN2Lizk3VNMf2RKfeb0=; b=TvtjtpuRnUNeqa4ox9eiwM+TRGYGRp6nHl0WD0h0jh1L1qZBp1t0gb4Syl884DL9iiF9O4 Ywr/lPLPwDGzoJGONPEEVd978BAQYVy3XS2ntb614c+36jIWb7QnF9v2dF8htTJOqPNswn UsHBHsuf4/8ChH+nPoQ1vbLzsjIAzZ8= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1731324633; a=rsa-sha256; cv=none; b=Y92vlEXpo+hCkO8PmpBLNndOnn/IVmFfrlzI58KyacXcCJ5MnYn1VefCVNsptiWgtcEezW pOlVw+0/cbm0XfzEHLbvaFqCsCnLeb+SJYH0974GFIegp66oRsVGTKIUiBQsB+xYxuziz9 Eio5wNytSKJ80zQSzRw/Y4/QlBEeoAQ= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=none; spf=pass (imf08.hostedemail.com: domain of linyunsheng@huawei.com designates 45.249.212.191 as permitted sender) smtp.mailfrom=linyunsheng@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.17]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4Xn6h05zhdz28fSh; Mon, 11 Nov 2024 19:26:40 +0800 (CST) Received: from dggpemf200006.china.huawei.com (unknown [7.185.36.61]) by mail.maildlp.com (Postfix) with ESMTPS id 6929B1A0188; Mon, 11 Nov 2024 19:31:22 +0800 (CST) Received: from [10.67.120.129] (10.67.120.129) by dggpemf200006.china.huawei.com (7.185.36.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Mon, 11 Nov 2024 19:31:22 +0800 Message-ID: <4564c77b-a54d-4307-b043-d08e314c4c5f@huawei.com> Date: Mon, 11 Nov 2024 19:31:21 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v3 3/3] page_pool: fix IOMMU crash when driver has already unbound From: Yunsheng Lin To: Jesper Dangaard Brouer , =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , , , CC: , , , Robin Murphy , Alexander Duyck , IOMMU , Andrew Morton , Eric Dumazet , Ilias Apalodimas , , , , kernel-team References: <20241022032214.3915232-1-linyunsheng@huawei.com> <20241022032214.3915232-4-linyunsheng@huawei.com> <113c9835-f170-46cf-92ba-df4ca5dfab3d@huawei.com> <878qudftsn.fsf@toke.dk> <87r084e8lc.fsf@toke.dk> <0c146fb8-4c95-4832-941f-dfc3a465cf91@kernel.org> <204272e7-82c3-4437-bb0d-2c3237275d1f@huawei.com> Content-Language: en-US In-Reply-To: <204272e7-82c3-4437-bb0d-2c3237275d1f@huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.120.129] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemf200006.china.huawei.com (7.185.36.61) X-Stat-Signature: ixteyiyan873ct1qtpopygytbqmdioe8 X-Rspam-User: X-Rspamd-Queue-Id: 99D3C16001A X-Rspamd-Server: rspam02 X-HE-Tag: 1731324659-547211 X-HE-Meta: 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 6pxpb7M8 U3R1eDhzlMJrhfbihm7pMb7LPbVpFscFuXsfR7nxJ2cDpsEMI9BRvWphlMwymPAKdh5OayWAAR4XGUKgZugt7cPF2c9Lbmyqll6TA8claCd/jg6fysdCPdGPgUHYXxgFhSUXA/XDlmBsg23PayIzmjk1/IARLJuhDIeOWZTcCAI4EcJbvtHkus8twhJ59anTt77JIWA/RU/mSJQaUloMEIrMFFhpGRlwsUkpQny3aDipVas1gXzw0WP4RgnDOndzUmICJ3zaGVXJBu/yLKZRiL57WbK52zv2p2ZbM 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 2024/10/26 15:33, Yunsheng Lin wrote: ... >>> >>> AFAIU Jakub's comment on his RFC patch for waiting, he was suggesting >>> exactly this: Add the wait, and see if the cases where it can stall turn >>> out to be problems in practice. >> >> +1 >> >> I like Jakub's approach. > > As mentioned in Toke's comment, I am still not convinced that there is some > easy way of waiting here, doing the kick in the kernel space is hard enough, > I am not even sure if kick need to be done or how it can be done in the user > space if some page_pool owned page is held from user space for the cases of zero > rx copy, io_uring and devmem tcp? killing the userspace app? > > If you and Toke still think the waiting is the way out for the problem here, maybe > we should wait for jakub's opinion and let him decide if he want to proceed with > his waiting patch. Is there any other suggestion/concern about how to fix the problem here? >From the previous discussion, it seems the main concern about tracking the inflight pages is about how many inflight pages it is needed. If there is no other suggestion/concern , it seems the above concern might be addressed by using pre-allocated memory to satisfy the mostly used case, and use the dynamically allocated memory if/when necessary.