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 smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 77D98CF3972 for ; Thu, 19 Sep 2024 21:05:00 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id D958161625; Thu, 19 Sep 2024 21:04:59 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id 809sFHQGYWNt; Thu, 19 Sep 2024 21:04:58 +0000 (UTC) X-Comment: SPF check N/A for local connections - client-ip=140.211.166.34; helo=ash.osuosl.org; envelope-from=intel-wired-lan-bounces@osuosl.org; receiver= DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 6482C60729 DKIM-Signature: v=1; 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Thu, 19 Sep 2024 21:04:56 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id kH92JLx17TcJ for ; Thu, 19 Sep 2024 21:04:55 +0000 (UTC) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=147.75.193.91; helo=nyc.source.kernel.org; envelope-from=hawk@kernel.org; receiver= DMARC-Filter: OpenDMARC Filter v1.4.2 smtp2.osuosl.org 999D2400E0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 999D2400E0 Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by smtp2.osuosl.org (Postfix) with ESMTPS id 999D2400E0 for ; Thu, 19 Sep 2024 21:04:55 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id C32F2A4402D; Thu, 19 Sep 2024 21:04:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A7DAEC4CEC4; Thu, 19 Sep 2024 21:04:45 +0000 (UTC) Message-ID: <0e8c7a7a-0e2a-42ec-adbc-b29f6a514517@kernel.org> Date: Thu, 19 Sep 2024 23:04:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Yunsheng Lin , Ilias Apalodimas References: <20240918111826.863596-1-linyunsheng@huawei.com> <20240918111826.863596-3-linyunsheng@huawei.com> <894a3c2c-22f9-45b9-a82b-de7320066b42@kernel.org> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726779893; bh=8rmdkhy7mle9GnzKV59Fez0ZiYJ5ItopN5knD5heul0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=tMIiZugOhjzqgyUpW7HkIMb94kB3G/IoEOWJvEfIibHaCL2W6lxj/6dAy50ww3Upd 5BuV7yd7+xf0LnJlLA6shnOsl4ybtmmnw4qRRAcxcVdTlQQO8CjzRoHuaAPl0cnLci KyO838TcaL8c8mfnqC3Fcz2LQ0BjvUfx2U9ux0XAeez0raNOeRSjsGu9186hqHSozD ekcF76hWo/vt3sl8iQ7tBHFkSTET2nmVrmZCljeeCkxJkkq5cSQY3mp+XWQ6e0oYMf Qo62AxytxEW4fp+yzCDxcmUUB+Wme/iNSXIqef4vFQ/XRD6jqsRg+/Yl4tOtEC8q6k c8Ol4+tfmgDUA== X-Mailman-Original-Authentication-Results: smtp2.osuosl.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org X-Mailman-Original-Authentication-Results: smtp2.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=tMIiZugO Subject: Re: [Intel-wired-lan] [PATCH net 2/2] page_pool: fix IOMMU crash when driver has already unbound X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: imx@lists.linux.dev, Alexei Starovoitov , Alexander Duyck , linux-mm@kvack.org, Eric Dumazet , Tony Nguyen , Shenwei Wang , Ryder Lee , Leon Romanovsky , linux-rdma@vger.kernel.org, Przemek Kitszel , John Fastabend , IOMMU , liuyonglong@huawei.com, Clark Wang , zhangkun09@huawei.com, fanghaiqing@huawei.com, pabeni@redhat.com, Lorenzo Bianconi , Kalle Valo , Sean Wang , Wei Fang , kuba@kernel.org, Matthias Brugger , intel-wired-lan@lists.osuosl.org, bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, AngeloGioacchino Del Regno , Daniel Borkmann , Robin Murphy , linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, Tariq Toukan , Alexander Lobakin , netdev@vger.kernel.org, linux-mediatek@lists.infradead.org, Andrew Morton , Shayne Chen , Saeed Mahameed , davem@davemloft.net, Felix Fietkau Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" On 19/09/2024 13.15, Yunsheng Lin wrote: > On 2024/9/19 17:42, Jesper Dangaard Brouer wrote: >> >> On 18/09/2024 19.06, Ilias Apalodimas wrote: >>>> In order not to do the dma unmmapping after driver has already >>>> unbound and stall the unloading of the networking driver, add >>>> the pool->items array to record all the pages including the ones >>>> which are handed over to network stack, so the page_pool can >>>> do the dma unmmapping for those pages when page_pool_destroy() >>>> is called. >>> >>> So, I was thinking of a very similar idea. But what do you mean by >>> "all"? The pages that are still in caches (slow or fast) of the pool >>> will be unmapped during page_pool_destroy(). >> >> I really dislike this idea of having to keep track of all outstanding pages. >> >> I liked Jakub's idea of keeping the netdev around for longer. >> >> This is all related to destroying the struct device that have points to >> the DMA engine, right? > > Yes, the problem seems to be that when device_del() is called, there is > no guarantee hw behind the 'struct device ' will be usable even if we > call get_device() on it. > >> >> Why don't we add an API that allow netdev to "give" struct device to >> page_pool.  And then the page_poll will take over when we can safely >> free the stuct device? > > By 'allow netdev to "give" struct device to page_pool', does it mean > page_pool become the driver for the device? > If yes, it seems that is similar to jakub's idea, as both seems to stall > the calling of device_del() by not returning when the driver unloading. Yes, this is what I mean. (That is why I mentioned Jakub's idea). > If no, it seems that the problem is still existed when the driver for > the device has unbound after device_del() is called.