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[81.157.153.247]) by smtp.gmail.com with ESMTPSA id p7-20020a05600c1d8700b003cf4eac8e80sm1611260wms.23.2023.01.04.23.28.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Jan 2023 23:28:21 -0800 (PST) Date: Thu, 5 Jan 2023 07:26:10 +0000 From: Lorenzo Stoakes To: Alistair Popple Cc: "Yu, Fenghua" , Vinod Koul , "Jiang, Dave" , "dmaengine@vger.kernel.org" , "Zhu, Tony" , Andrew Morton , "linux-mm@kvack.org" , Christoph Hellwig , "Shankar, Ravi V" Subject: Re: [PATCH 09/17] mm: export access_remote_vm() symbol Message-ID: References: <20230103163505.1569356-1-fenghua.yu@intel.com> <20230103163505.1569356-10-fenghua.yu@intel.com> <87tu16rdea.fsf@nvidia.com> <87k021vnmw.fsf@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k021vnmw.fsf@nvidia.com> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D9CF3A000A X-Stat-Signature: urxeeqa41b3bt46g6o65uygdxm36bafz X-HE-Tag: 1672903703-844168 X-HE-Meta: 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 fPc/PWwR bRbzGN4H6CM6wYeIzajYBUpSCSUYo1g6gr7CbBM3nnRCYTjx1HtiT4P1FKBgC0vlX4opFlqwRAOCKLD6GXjeAcqxZMjZvnrycUvQDKpn2saj3GdSD51V7BthqbRJZ6LU3q9Hgyj9S0FUmCJIrkxRSjtKQOx/6nnohk27MvHNkzNdn8I4= 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 Thu, Jan 05, 2023 at 10:57:02AM +1100, Alistair Popple wrote: > Ok, although I think making this an iommu specific wrapper taking a > PASID rather than mm_struct would make the API more specific and less > likely to be misused as the mm_count/users lifetime issues could be > dealt with inside the core IOMMU code. This sounds like the ideal approach, as long as we either mmgrab() or otherwise ensure that the mm won't disappear underneath us, then use mmget_not_zero() to get a reference in this wrapper function, I think we're gravy.