From: Jason Gunthorpe <jgg@ziepe.ca>
To: David Hildenbrand <david@redhat.com>
Cc: jean-philippe@linaro.org, kevin.tian@intel.com,
Sihang Chen <chensihang1@hisilicon.com>,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, linux-mm@kvack.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
gregkh@linuxfoundation.org, zhangfei.gao@linaro.org,
Andrew Morton <akpm@linux-foundation.org>,
liguozhu@hisilicon.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH v3 1/2] mempinfd: Add new syscall to provide memory pin
Date: Mon, 8 Feb 2021 14:33:48 -0400 [thread overview]
Message-ID: <20210208183348.GV4718@ziepe.ca> (raw)
In-Reply-To: <a587bd61-9194-4b46-c122-8b4da7b941a8@redhat.com>
On Mon, Feb 08, 2021 at 09:14:28AM +0100, David Hildenbrand wrote:
> People are constantly struggling with the effects of long term pinnings
> under user space control, like we already have with vfio and RDMA.
>
> And here we are, adding yet another, easier way to mess with core MM in the
> same way. This feels like a step backwards to me.
Yes, this seems like a very poor candidate to be a system call in this
format. Much too narrow, poorly specified, and possibly security
implications to allow any process whatsoever to pin memory.
I keep encouraging people to explore a standard shared SVA interface
that can cover all these topics (and no, uaccel is not that
interface), that seems much more natural.
I still haven't seen an explanation why DMA is so special here,
migration and so forth jitter the CPU too, environments that care
about jitter have to turn this stuff off.
Jason
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next prev parent reply other threads:[~2021-02-08 18:33 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-07 8:18 [RFC PATCH v3 0/2] mempinfd: Add new syscall to provide memory pin Zhou Wang
2021-02-07 8:18 ` [RFC PATCH v3 1/2] " Zhou Wang
2021-02-07 21:34 ` Matthew Wilcox
2021-02-07 22:24 ` Song Bao Hua (Barry Song)
2021-02-08 1:30 ` Matthew Wilcox
2021-02-08 2:27 ` Song Bao Hua (Barry Song)
2021-02-08 8:21 ` David Hildenbrand
2021-02-08 10:13 ` Song Bao Hua (Barry Song)
2021-02-08 10:37 ` David Hildenbrand
2021-02-08 20:52 ` Song Bao Hua (Barry Song)
2021-02-08 2:18 ` David Rientjes via iommu
2021-02-08 5:34 ` Song Bao Hua (Barry Song)
2021-02-07 21:51 ` Arnd Bergmann
2021-02-09 9:27 ` Zhou Wang
2021-02-07 22:02 ` Andy Lutomirski
2021-02-09 9:17 ` Zhou Wang
2021-02-09 9:37 ` Greg KH
2021-02-09 11:58 ` Zhou Wang
2021-02-09 12:01 ` Greg KH
2021-02-09 12:20 ` Zhou Wang
2021-02-10 18:50 ` Matthew Wilcox
2021-02-08 8:14 ` David Hildenbrand
2021-02-08 18:33 ` Jason Gunthorpe [this message]
2021-02-08 20:35 ` Song Bao Hua (Barry Song)
2021-02-08 21:30 ` Jason Gunthorpe
2021-02-09 3:01 ` Song Bao Hua (Barry Song)
2021-02-09 13:53 ` Jason Gunthorpe
2021-02-09 22:22 ` Song Bao Hua (Barry Song)
2021-02-10 18:04 ` Jason Gunthorpe
2021-02-10 21:39 ` Song Bao Hua (Barry Song)
2021-02-11 10:28 ` David Hildenbrand
2021-02-07 8:18 ` [RFC PATCH v3 2/2] selftests/vm: add mempinfd test Zhou Wang
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