netdev - Re: [PATCH v9 0/3] mm/gup: disallow GUP writing to file-backed mappings by default

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Message-ID: <ZGSFptUyOko+184t@infradead.org>
Date: Wed, 17 May 2023 00:43:34 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Lorenzo Stoakes <lstoakes@...il.com>
Cc: Jan Kara <jack@...e.cz>, Jason Gunthorpe <jgg@...dia.com>,
	"Kirill A . Shutemov" <kirill@...temov.name>, linux-mm@...ck.org,
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	Christian Borntraeger <borntraeger@...ux.ibm.com>
Subject: Re: [PATCH v9 0/3] mm/gup: disallow GUP writing to file-backed
 mappings by default

On Wed, May 17, 2023 at 08:40:26AM +0100, Lorenzo Stoakes wrote:
> > I'm not sure what you mean by "total flexibility" here. In my opinion it is
> > also about how HW performs checksumming etc.
> 
> I mean to say *_ops allow a lot of flexibility in how things are
> handled. Certainly checksumming is a great example but in theory an
> arbitrary filesystem could be doing, well, anything and always assuming
> that only userland mappings should be modifying the underlying data.

File systems need a wait to track when a page is dirtied so that it can
be written back.  Not much to do with flexbility.