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From: Jason Gunthorpe <jgg@nvidia.com>
To: David Hildenbrand <david@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>,
	Peter Xu <peterx@redhat.com>,
	Lorenzo Stoakes <lstoakes@gmail.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>,
	Matthew Wilcox <willy@infradead.org>,
	Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
	Leon Romanovsky <leon@kernel.org>,
	Christian Benvenuti <benve@cisco.com>,
	Nelson Escobar <neescoba@cisco.com>,
	Bernard Metzler <bmt@zurich.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Bjorn Topel <bjorn@kernel.org>,
	Magnus Karlsson <magnus.karlsson@intel.com>,
	Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
	Jonathan Lemon <jonathan.lemon@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Christian Brauner <brauner@kernel.org>,
	Richard Cochran <richardcochran@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	Oleg Nesterov <oleg@redhat.com>,
	John Hubbard <jhubbard@nvidia.com>, Jan Kara <jack@suse.cz>,
	Pavel Begunkov <asml.silence@gmail.com>,
	Mika Penttila <mpenttil@redhat.com>,
	David Howells <dhowells@redhat.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v5] mm/gup: disallow GUP writing to file-backed mappings by default
Date: Fri, 28 Apr 2023 14:31:38 -0300	[thread overview]
Message-ID: <ZEwC+viAMJ0vEpgU@nvidia.com> (raw)
In-Reply-To: <1039c830-acec-d99b-b315-c2a6e26c34ca@redhat.com>

On Fri, Apr 28, 2023 at 07:02:22PM +0200, David Hildenbrand wrote:

> > No. VMA cannot get away before PTEs are unmapped and TLB is flushed. And
> > TLB flushing is serialized against GUP_fast().
>
> The whole CONFIG_MMU_GATHER_RCU_TABLE_FREE handling makes the situation more
> complicated.

Yeah, you have to think of gup_fast as RCU with a hacky pre-RCU implementation
on most architectures.

We could make page->mapping safe under RCU, for instance.

Jason


  reply	other threads:[~2023-04-28 17:31 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-27 23:42 Lorenzo Stoakes
2023-04-28  2:06 ` John Hubbard
2023-04-28  4:21 ` Mika Penttilä
2023-04-28 11:51 ` Jan Kara
2023-04-28 11:59 ` Lorenzo Stoakes
2023-04-28 13:17 ` Jason Gunthorpe
2023-04-28 14:20 ` David Hildenbrand
2023-04-28 14:35   ` Jason Gunthorpe
2023-04-28 15:08     ` David Hildenbrand
2023-04-28 15:23       ` David Hildenbrand
2023-04-28 15:33         ` Lorenzo Stoakes
2023-04-28 15:34           ` David Hildenbrand
2023-04-28 15:43             ` David Hildenbrand
2023-04-28 16:09               ` Kirill A . Shutemov
2023-04-28 16:13                 ` David Hildenbrand
2023-04-28 16:22                   ` Kirill A . Shutemov
2023-04-28 16:39                     ` Peter Xu
2023-04-28 16:51                       ` David Hildenbrand
2023-04-28 16:56                         ` Kirill A . Shutemov
2023-04-28 17:01                           ` Lorenzo Stoakes
2023-04-28 17:02                           ` David Hildenbrand
2023-04-28 17:31                             ` Jason Gunthorpe [this message]
2023-04-28 17:42                               ` Lorenzo Stoakes
2023-04-28 17:49                                 ` Jason Gunthorpe
2023-04-28 23:43                             ` Kirill A . Shutemov
2023-05-02  8:00                               ` Jan Kara
2023-05-02  8:39                                 ` Peter Zijlstra
2023-04-28 17:01                         ` Lorenzo Stoakes
2023-04-28 17:05                           ` David Hildenbrand
2023-04-28 17:13                             ` Lorenzo Stoakes
2023-04-28 17:29                               ` David Hildenbrand
2023-04-28 18:26                                 ` John Hubbard
2023-04-28 15:56             ` Peter Xu
2023-04-28 16:02               ` David Hildenbrand
2023-04-28 17:33               ` Jason Gunthorpe
2023-04-28 18:26                 ` John Hubbard
2023-04-28 15:27       ` Jason Gunthorpe
2023-04-28 15:41         ` David Hildenbrand
2023-04-28 18:25     ` Theodore Ts'o
2023-04-28 18:50       ` Jason Gunthorpe
2023-04-29  4:21         ` Theodore Ts'o
2023-04-29 23:01           ` Jason Gunthorpe
2023-04-29 23:09             ` Lorenzo Stoakes
2023-05-01  7:27             ` Dave Chinner
2023-05-01 12:39               ` Jason Gunthorpe
2023-04-28 14:55   ` Lorenzo Stoakes
2023-04-28 15:13     ` David Hildenbrand
2023-04-28 15:15       ` Jens Axboe
2023-04-28 15:27         ` Lorenzo Stoakes
2023-04-28 15:24       ` Lorenzo Stoakes
2023-04-28 15:33         ` David Hildenbrand
2023-04-28 15:50           ` Lorenzo Stoakes
2023-04-28 16:00             ` David Hildenbrand

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