Re: [PATCH 0/3] mm, thp: introduce a new sysfs interface to facilitate file THP for .text

[Matthew Wilcox]

On Mon, Oct 11, 2021 at 09:06:37AM +0100, Christoph Hellwig wrote:
> Can we please just get proper pagecache THP (through folios) merged
> instead of piling hacks over hacks here?  The whole readonly THP already
> was more than painful enough due to all the hacks involved.

This was my initial reaction too.

But read the patches.  They're nothing to do with the implementation of
THP / folios in the page cache.  They're all to make sure that mappings
are PMD aligned.

I think there's a lot to criticise in the patches (eg, a system-wide
setting is probably a bad idea.  and a lot of this stuff seems to
be fixing userspace bugs in the kernel).  But let's criticise what's
actually in the patches, because these are problems that exist regardless
of RO_THP vs folios.