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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Joao Martins <joao.m.martins@oracle.com>,
	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 <david@fromorbit.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH 3/3] mm/devmap: Remove pgmap accounting in the get_user_pages_fast() path
Date: Tue, 30 Mar 2021 10:49:53 -0300	[thread overview]
Message-ID: <20210330134953.GT2710221@ziepe.ca> (raw)
In-Reply-To: <CAPcyv4hHHFD4cvdRmajWgYbXU5-o-jF-o6D5ud-rg4dWNqt5Ag@mail.gmail.com>

On Mon, Mar 29, 2021 at 04:24:19PM -0700, Dan Williams wrote:
> On Thu, Mar 25, 2021 at 7:34 AM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> >
> > On Thu, Mar 18, 2021 at 10:03:06AM -0700, Dan Williams wrote:
> > > Yes. I still need to answer the question of whether mapping
> > > invalidation triggers longterm pin holders to relinquish their hold,
> > > but that's a problem regardless of whether gup-fast is supported or
> > > not.
> >
> > It does not, GUP users do not interact with addres_space or mmu
> > notifiers
> 
> Ok, but the SIGKILL from the memory_failure() will drop the pin?

In the general case I doubt it..

I think this is fine, we shouldn't expect unplugging a driver to not
block if there are open users.

Demading DMA users to be able to shoot down access to system memory is
a really big kernel change.

Jason

  reply	other threads:[~2021-03-30 13:50 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 [this message]
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
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

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