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[142.162.115.133]) by smtp.gmail.com with ESMTPSA id o76sm409454qke.104.2021.01.25.07.47.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 07:47:18 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l445F-006YE8-Qg; Mon, 25 Jan 2021 11:47:17 -0400 Date: Mon, 25 Jan 2021 11:47:17 -0400 From: Jason Gunthorpe To: Zhou Wang Cc: Greg Kroah-Hartman , Arnd Bergmann , Zhangfei Gao , linux-accelerators@lists.ozlabs.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-mm@kvack.org, song.bao.hua@hisilicon.com, liguozhu@hisilicon.com, Sihang Chen Subject: Re: [RFC PATCH v2] uacce: Add uacce_ctrl misc device Message-ID: <20210125154717.GW4605@ziepe.ca> References: <1611563696-235269-1-git-send-email-wangzhou1@hisilicon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1611563696-235269-1-git-send-email-wangzhou1@hisilicon.com> 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 Mon, Jan 25, 2021 at 04:34:56PM +0800, Zhou Wang wrote: > +static int uacce_pin_page(struct uacce_pin_container *priv, > + struct uacce_pin_address *addr) > +{ > + unsigned int flags = FOLL_FORCE | FOLL_WRITE; > + unsigned long first, last, nr_pages; > + struct page **pages; > + struct pin_pages *p; > + int ret; > + > + first = (addr->addr & PAGE_MASK) >> PAGE_SHIFT; > + last = ((addr->addr + addr->size - 1) & PAGE_MASK) >> PAGE_SHIFT; > + nr_pages = last - first + 1; > + > + pages = vmalloc(nr_pages * sizeof(struct page *)); > + if (!pages) > + return -ENOMEM; > + > + p = kzalloc(sizeof(*p), GFP_KERNEL); > + if (!p) { > + ret = -ENOMEM; > + goto free; > + } > + > + ret = pin_user_pages_fast(addr->addr & PAGE_MASK, nr_pages, > + flags | FOLL_LONGTERM, pages); This needs to copy the RLIMIT_MEMLOCK and can_do_mlock() stuff from other places, like ib_umem_get > + ret = xa_err(xa_store(&priv->array, p->first, p, GFP_KERNEL)); And this is really weird, I don't think it makes sense to make handles for DMA based on the starting VA. > +static int uacce_unpin_page(struct uacce_pin_container *priv, > + struct uacce_pin_address *addr) > +{ > + unsigned long first, last, nr_pages; > + struct pin_pages *p; > + > + first = (addr->addr & PAGE_MASK) >> PAGE_SHIFT; > + last = ((addr->addr + addr->size - 1) & PAGE_MASK) >> PAGE_SHIFT; > + nr_pages = last - first + 1; > + > + /* find pin_pages */ > + p = xa_load(&priv->array, first); > + if (!p) > + return -ENODEV; > + > + if (p->nr_pages != nr_pages) > + return -EINVAL; > + > + /* unpin */ > + unpin_user_pages(p->pages, p->nr_pages); And unpinning without guaranteeing there is no ongoing DMA is really weird Are you abusing this in conjunction with a SVA scheme just to prevent page motion? Why wasn't mlock good enough? Jason