Re: [PATCH v20 00/32] splice, block: Use page pinning and kill ITER_PIPE

[Christoph Hellwig]

On Fri, May 19, 2023 at 08:40:15AM +0100, David Howells wrote:
> Hi Jens, Al, Christoph,
> 
> The first half of this patchset kills off ITER_PIPE to avoid a race between
> truncate, iov_iter_revert() on the pipe and an as-yet incomplete DMA to a
> bio with unpinned/unref'ed pages from an O_DIRECT splice read.  This causes
> memory corruption[2].  Instead, we use filemap_splice_read(), which invokes
> the buffered file reading code and splices from the pagecache into the
> pipe; direct_splice_read(), which bulk-allocates a buffer, reads into it
> and then pushes the filled pages into the pipe; or handle it in
> filesystem-specific code.

If there's a clearly separate first and second half of a 32 patch
series, it might really make sense to just split it instead of exceeding
every normal attention window..