linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jerome Glisse <jglisse@redhat.com>
Cc: "Leon Romanovsky" <leon@kernel.org>,
	"Kenneth Lee" <liguozhu@hisilicon.com>,
	"Tim Sell" <timothy.sell@unisys.com>,
	linux-doc@vger.kernel.org,
	"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
	"Zaibo Xu" <xuzaibo@huawei.com>,
	zhangfei.gao@foxmail.com, linuxarm@huawei.com,
	haojian.zhuang@linaro.org, "Christoph Lameter" <cl@linux.com>,
	"Hao Fang" <fanghao11@huawei.com>,
	"Gavin Schenk" <g.schenk@eckelmann.de>,
	"RDMA mailing list" <linux-rdma@vger.kernel.org>,
	"Zhou Wang" <wangzhou1@hisilicon.com>,
	"Doug Ledford" <dledford@redhat.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"David Kershner" <david.kershner@unisys.com>,
	"Kenneth Lee" <nek.in.cn@gmail.com>,
	"Johan Hovold" <johan@kernel.org>,
	"Cyrille Pitchen" <cyrille.pitchen@free-electrons.com>,
	"Sagar Dharia" <sdharia@codeaurora.org>,
	"Jens Axboe" <axboe@kernel.dk>,
	guodong.xu@linaro.org, linux-netdev <netdev@vger.kernel.org>,
	"Randy Dunlap" <rdunlap@infradead.org>,
	linux-kernel@vger.kernel.org, "Vinod Koul" <vkoul@kernel.org>,
	linux-crypto@vger.kernel.org,
	"Philippe Ombredanne" <pombredanne@nexb.com>,
	"Sanyog Kale" <sanyog.r.kale@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	linux-accelerators@lists.ozlabs.org
Subject: Re: [RFCv3 PATCH 1/6] uacce: Add documents for WarpDrive/uacce
Date: Mon, 19 Nov 2018 11:27:52 -0700	[thread overview]
Message-ID: <20181119182752.GA4890@ziepe.ca> (raw)
In-Reply-To: <20181119164853.GA4593@redhat.com>

On Mon, Nov 19, 2018 at 11:48:54AM -0500, Jerome Glisse wrote:

> Just to comment on this, any infiniband driver which use umem and do
> not have ODP (here ODP for me means listening to mmu notifier so all
> infiniband driver except mlx5) will be affected by same issue AFAICT.
> 
> AFAICT there is no special thing happening after fork() inside any of
> those driver. So if parent create a umem mr before fork() and program
> hardware with it then after fork() the parent might start using new
> page for the umem range while the old memory is use by the child. The
> reverse is also true (parent using old memory and child new memory)
> bottom line you can not predict which memory the child or the parent
> will use for the range after fork().
> 
> So no matter what you consider the child or the parent, what the hw
> will use for the mr is unlikely to match what the CPU use for the
> same virtual address. In other word:
> 
> Before fork:
>     CPU parent: virtual addr ptr1 -> physical address = 0xCAFE
>     HARDWARE:   virtual addr ptr1 -> physical address = 0xCAFE
> 
> Case 1:
>     CPU parent: virtual addr ptr1 -> physical address = 0xCAFE
>     CPU child:  virtual addr ptr1 -> physical address = 0xDEAD
>     HARDWARE:   virtual addr ptr1 -> physical address = 0xCAFE
> 
> Case 2:
>     CPU parent: virtual addr ptr1 -> physical address = 0xBEEF
>     CPU child:  virtual addr ptr1 -> physical address = 0xCAFE
>     HARDWARE:   virtual addr ptr1 -> physical address = 0xCAFE

IIRC this is solved in IB by automatically calling
madvise(MADV_DONTFORK) before creating the MR.

MADV_DONTFORK
  .. This is useful to prevent copy-on-write semantics from changing the
  physical location of a page if the parent writes to it after a
  fork(2) ..

Jason

  reply	other threads:[~2018-11-19 18:27 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-12  7:58 [RFCv3 PATCH 0/6] A General Accelerator Framework, WarpDrive Kenneth Lee
2018-11-12  7:58 ` [RFCv3 PATCH 1/6] uacce: Add documents for WarpDrive/uacce Kenneth Lee
2018-11-13  0:23   ` Leon Romanovsky
2018-11-14  2:58     ` Kenneth Lee
2018-11-14 16:00       ` Leon Romanovsky
2018-11-15  8:51         ` Kenneth Lee
2018-11-15 14:54           ` Leon Romanovsky
2018-11-19  9:14             ` Kenneth Lee
2018-11-19  9:19               ` Kenneth Lee
2018-11-19 10:48                 ` Leon Romanovsky
2018-11-19 16:48                   ` Jerome Glisse
2018-11-19 18:27                     ` Jason Gunthorpe [this message]
2018-11-19 18:42                       ` Jerome Glisse
2018-11-19 18:53                         ` Jason Gunthorpe
2018-11-19 19:17                           ` Jerome Glisse
2018-11-19 19:27                             ` Jason Gunthorpe
2018-11-19 19:46                               ` Jerome Glisse
2018-11-19 20:11                                 ` Jason Gunthorpe
2018-11-19 20:26                                   ` Jerome Glisse
2018-11-19 21:26                                     ` Jason Gunthorpe
2018-11-19 21:33                                       ` Jerome Glisse
2018-11-19 21:41                                         ` Jason Gunthorpe
2018-11-19 19:02                         ` Leon Romanovsky
2018-11-19 19:19                         ` Christopher Lameter
2018-11-19 19:25                           ` Jerome Glisse
2018-11-20  2:30                   ` Kenneth Lee
2018-11-27  2:52                     ` Kenneth Lee
2018-11-19 18:49               ` Jason Gunthorpe
2018-11-20  3:07                 ` Kenneth Lee
2018-11-20  3:29                   ` Jason Gunthorpe
2018-11-20  9:16                     ` Jonathan Cameron
2018-11-20 12:19                       ` Jean-Philippe Brucker
2018-11-21  6:08                     ` Kenneth Lee
2018-11-22  2:58                       ` Jason Gunthorpe
2018-11-23  8:02                         ` Kenneth Lee
2018-11-23 18:05                           ` Jason Gunthorpe
2018-11-24  4:13                             ` Kenneth Lee
2018-11-20  5:17                   ` Leon Romanovsky
2018-11-21  3:02                     ` Kenneth Lee
2018-11-12  7:58 ` [RFCv3 PATCH 2/6] uacce: add uacce module Kenneth Lee
2018-11-12  7:58 ` [RFCv3 PATCH 3/6] crypto/hisilicon: add hisilicon Queue Manager driver Kenneth Lee
2018-11-12  7:58 ` [RFCv3 PATCH 4/6] crypto/hisilicon: add Hisilicon zip driver Kenneth Lee
2018-11-12  7:58 ` [RFCv3 PATCH 5/6] crypto: add uacce support to Hisilicon qm Kenneth Lee
2018-11-12  7:58 ` [RFCv3 PATCH 6/6] uacce: add user sample for uacce/warpdrive Kenneth Lee

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20181119182752.GA4890@ziepe.ca \
    --to=jgg@ziepe.ca \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=axboe@kernel.dk \
    --cc=cl@linux.com \
    --cc=cyrille.pitchen@free-electrons.com \
    --cc=davem@davemloft.net \
    --cc=david.kershner@unisys.com \
    --cc=dledford@redhat.com \
    --cc=fanghao11@huawei.com \
    --cc=g.schenk@eckelmann.de \
    --cc=guodong.xu@linaro.org \
    --cc=haojian.zhuang@linaro.org \
    --cc=jglisse@redhat.com \
    --cc=johan@kernel.org \
    --cc=leon@kernel.org \
    --cc=liguozhu@hisilicon.com \
    --cc=linux-accelerators@lists.ozlabs.org \
    --cc=linux-crypto@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=linuxarm@huawei.com \
    --cc=nek.in.cn@gmail.com \
    --cc=netdev@vger.kernel.org \
    --cc=pombredanne@nexb.com \
    --cc=rdunlap@infradead.org \
    --cc=sanyog.r.kale@intel.com \
    --cc=sdharia@codeaurora.org \
    --cc=timothy.sell@unisys.com \
    --cc=u.kleine-koenig@pengutronix.de \
    --cc=vkoul@kernel.org \
    --cc=wangzhou1@hisilicon.com \
    --cc=xuzaibo@huawei.com \
    --cc=zhangfei.gao@foxmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).