linux-kernel - Re: [RFC PATCH 1/4] splice: Fix corruption of spliced data after splice() returns

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Message-ID: <CAJfpegsJuvXJDcXpo9T19Gw0tDuvyOJdv44Y2bt04MEf1JLxGg@mail.gmail.com>
Date:   Wed, 19 Jul 2023 12:17:51 +0200
From:   Miklos Szeredi <miklos@...redi.hu>
To:     David Howells <dhowells@...hat.com>
Cc:     netdev@...r.kernel.org, Matthew Wilcox <willy@...radead.org>,
        Dave Chinner <david@...morbit.com>,
        Matt Whitlock <kernel@...twhitlock.name>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jens Axboe <axboe@...nel.dk>, linux-fsdevel@...ck.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@....de>, linux-fsdevel@...r.kernel.org
Subject: Re: [RFC PATCH 1/4] splice: Fix corruption of spliced data after
 splice() returns

On Thu, 29 Jun 2023 at 17:56, David Howells <dhowells@...hat.com> wrote:
>
> Splicing data from, say, a file into a pipe currently leaves the source
> pages in the pipe after splice() returns - but this means that those pages
> can be subsequently modified by shared-writable mmap(), write(),
> fallocate(), etc. before they're consumed.

What is this trying to fix?   The above behavior is well known, so
it's not likely to be a problem.

Besides, removing spliced pages from the cache is basically guaranteed
to result in a performance regression for any application using
splice.

Thanks,
Miklos