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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue, 14 Mar 2023 16:39:55 -0700
Message-ID: <CAHk-=whKPK=Bn_je2A19rSptpDo589DWxBJi8UQYS7sPjDPurw@mail.gmail.com>
Subject: Re: [PATCH v18 03/15] shmem: Implement splice-read
To:     David Howells <dhowells@redhat.com>
Cc:     Jens Axboe <axboe@kernel.dk>, Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
        Jeff Layton <jlayton@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Hillf Danton <hdanton@sina.com>,
        Christian Brauner <brauner@kernel.org>,
        linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Daniel Golle <daniel@makrotopia.org>,
        Guenter Roeck <groeck7@gmail.com>,
        Christoph Hellwig <hch@lst.de>,
        John Hubbard <jhubbard@nvidia.com>,
        Hugh Dickins <hughd@google.com>
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On Tue, Mar 14, 2023 at 3:08=E2=80=AFPM David Howells <dhowells@redhat.com>=
 wrote:
>
\> +static size_t splice_zeropage_into_pipe(...
>   ...
> +               *buf =3D (struct pipe_buffer) {
> +                       .ops    =3D &zero_pipe_buf_ops,
> +                       .page   =3D ZERO_PAGE(0),
> +                       .offset =3D offset,
> +                       .len    =3D size,
> +               };
> +               get_page(buf->page);

That

+               get_page(buf->page);

is still there, and now it's doubly wrong because it's never dropped
and will eventually overflow that count that shouldn't even be there.

             Linus