All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org, linux-nvdimm@lists.01.org,
	Christoph Hellwig <hch@lst.de>,
	Shiyang Ruan <ruansy.fnst@fujitsu.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Ira Weiny <ira.weiny@intel.com>,
	Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	david@fromorbit.com, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] mm/devmap: Remove pgmap accounting in the get_user_pages_fast() path
Date: Thu, 25 Mar 2021 11:37:30 -0300	[thread overview]
Message-ID: <20210325143730.GL2710221@ziepe.ca> (raw)
In-Reply-To: <161604050866.1463742.7759521510383551055.stgit@dwillia2-desk3.amr.corp.intel.com>

On Wed, Mar 17, 2021 at 09:08:28PM -0700, Dan Williams wrote:
> Now that device-dax and filesystem-dax are guaranteed to unmap all user
> mappings of devmap / DAX pages before tearing down the 'struct page'
> array, get_user_pages_fast() can rely on its traditional synchronization
> method "validate_pte(); get_page(); revalidate_pte()" to catch races with
> device shutdown. Specifically the unmap guarantee ensures that gup-fast
> either succeeds in taking a page reference (lock-less), or it detects a
> need to fall back to the slow path where the device presence can be
> revalidated with locks held.
> 
> Reported-by: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  mm/gup.c |   38 ++++++++++++++++----------------------
>  1 file changed, 16 insertions(+), 22 deletions(-)

I'm happy to see this, and it is really the right thing that PTEs are
properly removed before anything happens to the pages under them.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

  parent reply	other threads:[~2021-03-25 14:38 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-18  4:08 [PATCH 0/3] mm, pmem: Force unmap pmem on surprise remove Dan Williams
2021-03-18  4:08 ` Dan Williams
2021-03-18  4:08 ` [PATCH 1/3] mm/memory-failure: Prepare for mass memory_failure() Dan Williams
2021-03-18  4:08   ` Dan Williams
2021-03-18  4:08 ` [PATCH 2/3] mm, dax, pmem: Introduce dev_pagemap_failure() Dan Williams
2021-03-18  4:08   ` Dan Williams
2021-03-18  4:45   ` Darrick J. Wong
2021-03-18  4:45     ` Darrick J. Wong
2021-03-18 19:26     ` Dan Williams
2021-03-18 19:26       ` Dan Williams
2021-03-18 19:26       ` Dan Williams
2021-03-18  4:57   ` Dave Chinner
2021-03-18  4:57     ` Dave Chinner
2021-03-18 19:20     ` Dan Williams
2021-03-18 19:20       ` Dan Williams
2021-03-18 19:20       ` Dan Williams
2021-03-20  1:46       ` Dave Chinner
2021-03-20  1:46         ` Dave Chinner
2021-03-20  2:39         ` Dan Williams
2021-03-20  2:39           ` Dan Williams
2021-03-20  2:39           ` Dan Williams
2021-03-18  4:08 ` [PATCH 3/3] mm/devmap: Remove pgmap accounting in the get_user_pages_fast() path Dan Williams
2021-03-18  4:08   ` Dan Williams
2021-03-18 10:00   ` Joao Martins
2021-03-18 10:00     ` Joao Martins
2021-03-18 17:03     ` Dan Williams
2021-03-18 17:03       ` Dan Williams
2021-03-18 17:03       ` Dan Williams
2021-03-25 14:34       ` Jason Gunthorpe
2021-03-29 23:24         ` Dan Williams
2021-03-29 23:24           ` Dan Williams
2021-03-29 23:24           ` Dan Williams
2021-03-30 13:49           ` Jason Gunthorpe
2021-03-24 17:45     ` Dan Williams
2021-03-24 17:45       ` Dan Williams
2021-03-24 17:45       ` Dan Williams
2021-03-24 19:00       ` Joao Martins
2021-03-24 19:00         ` Joao Martins
2021-04-01 19:54         ` Joao Martins
2021-04-01 19:54           ` Joao Martins
2021-03-25 14:37   ` Jason Gunthorpe [this message]
2021-03-25 13:02 ` [PATCH 0/3] mm, pmem: Force unmap pmem on surprise remove David Hildenbrand
2021-03-25 13:02   ` David Hildenbrand

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=20210325143730.GL2710221@ziepe.ca \
    --to=jgg@ziepe.ca \
    --cc=akpm@linux-foundation.org \
    --cc=dan.j.williams@intel.com \
    --cc=dave.jiang@intel.com \
    --cc=david@fromorbit.com \
    --cc=hch@lst.de \
    --cc=ira.weiny@intel.com \
    --cc=jack@suse.cz \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=ruansy.fnst@fujitsu.com \
    --cc=vishal.l.verma@intel.com \
    --cc=willy@infradead.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.