From: Jason Gunthorpe <jgg@ziepe.ca>
To: Zhou Wang <wangzhou1@hisilicon.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Zhangfei Gao <zhangfei.gao@linaro.org>,
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 <chensihang1@hisilicon.com>
Subject: Re: [RFC PATCH v2] uacce: Add uacce_ctrl misc device
Date: Mon, 25 Jan 2021 11:47:17 -0400 [thread overview]
Message-ID: <20210125154717.GW4605@ziepe.ca> (raw)
In-Reply-To: <1611563696-235269-1-git-send-email-wangzhou1@hisilicon.com>
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
next prev parent reply other threads:[~2021-01-25 15:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-25 8:34 [RFC PATCH v2] uacce: Add uacce_ctrl misc device Zhou Wang
2021-01-25 9:28 ` Greg Kroah-Hartman
2021-01-25 12:47 ` Zhou Wang
2021-01-25 15:47 ` Jason Gunthorpe [this message]
2021-01-25 22:21 ` Song Bao Hua (Barry Song)
2021-01-25 23:16 ` Jason Gunthorpe
2021-01-25 23:35 ` Song Bao Hua (Barry Song)
2021-01-26 1:13 ` Jason Gunthorpe
2021-01-26 1:26 ` Song Bao Hua (Barry Song)
2021-01-26 18:20 ` Jason Gunthorpe
2021-01-28 1:28 ` Song Bao Hua (Barry Song)
[not found] ` <MWHPR11MB1886DC78C5FBA3636B94F2578CB99@MWHPR11MB1886.namprd11.prod.outlook.com>
2021-02-01 23:44 ` Jason Gunthorpe
2021-02-02 0:22 ` Song Bao Hua (Barry Song)
2021-02-02 2:51 ` Tian, Kevin
2021-02-02 3:47 ` Song Bao Hua (Barry Song)
2021-01-26 9:00 ` Zhou Wang
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