Re: [PATCH v3 0/7] Split a folio to any lower order folios

[Andrew Morton]

On Sun, 16 Apr 2023 11:11:49 -0700 (PDT) Hugh Dickins <hughd@xxxxxxxxxx> wrote:

> On Tue, 4 Apr 2023, Andrew Morton wrote:
> > On Mon,  3 Apr 2023 16:18:32 -0400 Zi Yan <zi.yan@xxxxxxxx> wrote:
> > 
> > > File folio supports any order and people would like to support flexible orders
> > > for anonymous folio[1] too. Currently, split_huge_page() only splits a huge
> > > page to order-0 pages, but splitting to orders higher than 0 is also useful.
> > > This patchset adds support for splitting a huge page to any lower order pages
> > > and uses it during file folio truncate operations.
> > 
> > This series (and its v1 & v2) don't appear to have much in the way of
> > detailed review.  As it's at v3 and has been fairly stable I'll queue
> > it up for some testing now, but I do ask that some reviewers go through
> > it please.
> 
> Andrew, please don't let this series drift into 6.4-rc1.

I have it still parked awaiting some reviewer input.

> I've seen a bug or two (I'll point out in response to those patches),
> but overall I don't see what the justification for the series is: done
> because it could be done, it seems to me, but liable to add surprises.
> 
> The cover letter says "splitting to orders higher than 0 is also useful",
> but it's not clear why; and the infrastructure provided seems unsuited
> to the one use provided - I'll say more on that truncation patch.

OK, I'll drop the series for this cycle.