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d=hostedemail.com; t=1730968835; a=rsa-sha256; cv=none; b=Owme8u6SmVagpCQM4slsFJraCpPjSrWiN+Ci8QO/eidAatUDo9rtiNRTb7q6BqO1P4yzPN UnIzXC4C4LSIit/gsyrG7Fnvga86pIlvVBMNkaEe4hikQjGlVF0ISUTMHkxG2kHKIlcYaj aNWpm4o5NP4N7DMniyZDYVKiEt2/dQc= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=none; spf=pass (imf04.hostedemail.com: domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de; dmarc=none Received: by verein.lst.de (Postfix, from userid 2407) id 898A968AA6; Thu, 7 Nov 2024 09:41:18 +0100 (CET) Date: Thu, 7 Nov 2024 09:41:17 +0100 From: Christoph Hellwig To: Yunsheng Lin Cc: Jesper Dangaard Brouer , Toke =?iso-8859-1?Q?H=F8iland-J=F8rgensen?= , davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, zhangkun09@huawei.com, fanghaiqing@huawei.com, liuyonglong@huawei.com, Robin Murphy , Alexander Duyck , IOMMU , Andrew Morton , Eric Dumazet , Ilias Apalodimas , linux-mm@kvack.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kernel-team , Christoph Hellwig , m.szyprowski@samsung.com Subject: Re: [PATCH net-next v3 3/3] page_pool: fix IOMMU crash when driver has already unbound Message-ID: <20241107084117.GA9712@lst.de> References: <87r084e8lc.fsf@toke.dk> <878qu7c8om.fsf@toke.dk> <1eac33ae-e8e1-4437-9403-57291ba4ced6@huawei.com> <87o731by64.fsf@toke.dk> <023fdee7-dbd4-4e78-b911-a7136ff81343@huawei.com> <874j4sb60w.fsf@toke.dk> <2f256bce-0c37-4940-9218-9545daa46169@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2f256bce-0c37-4940-9218-9545daa46169@huawei.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Stat-Signature: pzks7afwtgqu49d5mcyn1jrd68mcue6d X-Rspam-User: X-Rspamd-Queue-Id: D7BA140008 X-Rspamd-Server: rspam02 X-HE-Tag: 1730968840-598145 X-HE-Meta: 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 hqeXx0Dg 2DjjD0mSFmBR1ub9/CCNvdryE+KDiLoS8g7ui1GTgqFpKf6nMGP8WKvdgHTc+MurQxD+W0hqD/wMPYoQ0RfkVEH0oM/m/c+a8xZejkur+SpD3ERKfhMAkxVmq7xFT0yI6BS9dMYjTi+e9U8C+JvKAgK8NlCzy0zgsUjxDqZYFNDp1t8FVeO4A7fx50yc1f6OWU3ir 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 Wed, Nov 06, 2024 at 06:56:34PM +0800, Yunsheng Lin wrote: > > It is a very radical change that page_pool needs to keep track of *ALL* in-flight pages. > > I am agreed that it is a radical change, that is why it is targetting net-next > tree instead of net tree even when there is a Fixes tag for it. > > If there is a proper and non-radical way to fix that, I would prefer the > non-radical way too. As Robin already correctly pointed out DMA mappings fundamentally can't outlive the devices they were performed on. So I don't think there will be much hope for a non-radical fix for this design fault.