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From: Christoph Hellwig <hch@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Christoph Hellwig <hch@infradead.org>,
	Matthew Wilcox <willy@infradead.org>,
	Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
	Jeff Layton <jlayton@kernel.org>,
	Logan Gunthorpe <logang@deltatee.com>,
	linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	John Hubbard <jhubbard@nvidia.com>,
	linux-mm@kvack.org
Subject: Re: [PATCH v7 2/8] iov_iter: Add a function to extract a page list from an iterator
Date: Sat, 21 Jan 2023 05:10:18 -0800	[thread overview]
Message-ID: <Y8vkOk68ZFWPr9vq@infradead.org> (raw)
In-Reply-To: <20230120175556.3556978-3-dhowells@redhat.com>

On Fri, Jan 20, 2023 at 05:55:50PM +0000, David Howells wrote:
>  (3) Any other sort of iterator.
> 
>      No refs or pins are obtained on the page, the assumption is made that
>      the caller will manage page retention.  ITER_ALLOW_P2PDMA is not
>      permitted.

The ITER_ALLOW_P2PDMA check here is fundamentally wrong and will
break things like io_uring to fixed buffers on NVMe.  ITER_ALLOW_P2PDMA
should strictly increase the group of acceptable iters, it does must
not restrict anything.

  parent reply	other threads:[~2023-01-21 13:10 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-20 17:55 [PATCH v7 0/8] iov_iter: Improve page extraction (ref, pin or just list) David Howells
2023-01-20 17:55 ` [PATCH v7 1/8] iov_iter: Define flags to qualify page extraction David Howells
2023-01-21 13:01   ` Christoph Hellwig
2023-01-20 17:55 ` [PATCH v7 2/8] iov_iter: Add a function to extract a page list from an iterator David Howells
2023-01-21 13:01   ` Christoph Hellwig
2023-01-21 13:10   ` Christoph Hellwig [this message]
2023-01-21 13:30   ` David Howells
2023-01-21 13:33     ` Christoph Hellwig
2023-01-23 11:28   ` David Hildenbrand
2023-01-23 11:51   ` David Howells
2023-01-23 13:11     ` David Hildenbrand
2023-01-23 13:19     ` David Howells
2023-01-23 13:24       ` David Hildenbrand
2023-01-23 19:56         ` John Hubbard
2023-01-26 22:15         ` Al Viro
2023-01-26 23:41           ` David Hildenbrand
2023-01-27  0:05           ` David Howells
2023-01-27  0:20             ` David Hildenbrand
2023-01-23 13:38       ` David Howells
2023-01-23 14:20         ` David Hildenbrand
2023-01-23 14:48           ` Christoph Hellwig
2023-01-23 16:11         ` Jan Kara
2023-01-23 16:17           ` Christoph Hellwig
2023-01-23 23:07           ` John Hubbard
2023-01-24  5:57             ` Christoph Hellwig
2023-01-24  6:55               ` John Hubbard
2023-01-23 12:00   ` David Howells
2023-01-23 12:00     ` David Howells
2023-01-20 17:55 ` [PATCH v7 3/8] mm: Provide a helper to drop a pin/ref on a page David Howells
2023-01-20 17:55 ` [PATCH v7 4/8] block: Rename BIO_NO_PAGE_REF to BIO_PAGE_REFFED and invert the meaning David Howells
2023-01-21 13:04   ` Christoph Hellwig
2023-01-23  9:38   ` David Howells
2023-01-23  9:56     ` Christoph Hellwig
2023-01-20 17:55 ` [PATCH v7 5/8] block: Add BIO_PAGE_PINNED David Howells
2023-01-21 13:05   ` Christoph Hellwig
2023-01-20 17:55 ` [PATCH v7 6/8] block: Make bio structs pin pages rather than ref'ing if appropriate David Howells
2023-01-21 13:07   ` Christoph Hellwig
2023-01-23 11:28   ` David Howells
2023-01-23 14:49     ` Christoph Hellwig
2023-01-20 17:55 ` [PATCH v7 7/8] block: Fix bio_flagged() so that gcc can better optimise it David Howells
2023-01-20 17:55 ` [PATCH v7 8/8] mm: Renumber FOLL_GET and FOLL_PIN down David Howells
2023-01-20 18:59   ` Matthew Wilcox
2023-01-20 19:18   ` David Howells
2023-01-23 16:31 ` [PATCH v7 0/8] iov_iter: Improve page extraction (ref, pin or just list) Matthew Wilcox
2023-01-23 16:42   ` Jan Kara
2023-01-23 17:33     ` Matthew Wilcox
2023-01-23 22:53       ` John Hubbard
2023-01-24 10:29       ` Jan Kara
2023-01-24 13:21         ` Christoph Hellwig
2023-01-23 16:38 ` David Howells
2023-01-23 16:42   ` Matthew Wilcox
2023-01-23 17:25     ` Jan Kara
2023-01-24 10:24       ` David Hildenbrand
2023-01-23 17:19   ` David Howells
2023-01-23 18:04     ` Matthew Wilcox

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