Re: + maple_tree-shrink-struct-maple_tree-from-24-to-16-bytes-on-lp64.patch added to mm-unstable branch

[Matthew Wilcox <willy@infradead.org>]

On Tue, Aug 22, 2023 at 08:57:46PM +0200, Mateusz Guzik wrote:
> On 8/22/23, Matthew Wilcox <willy@infradead.org> wrote:
> > On Tue, Aug 22, 2023 at 11:44:54AM -0700, Andrew Morton wrote:
> >> ------------------------------------------------------
> >> From: Mateusz Guzik <mjguzik@gmail.com>
> >> Subject: maple_tree: shrink struct maple_tree from 24 to 16 bytes on LP64
> >> Date: Tue, 22 Aug 2023 00:51:45 +0200
> >>
> >> by plugging a padding hole.
> >>
> >> Link:
> >> https://lkml.kernel.org/r/20230821225145.2169848-1-mjguzik@gmail.com
> >> Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
> >> Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
> >> Cc: Matthew Wilcox <willy@infradead.org>
> >> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> >> ---
> >
> > Could we perhaps amend the commit log?
> >
> > Subject: maple_tree: Shrink struct maple_tree
> >
> > Pack the members of struct maple_tree to avoid holes on 64-bit.
> > The size shrinks from 24 to 16 bytes which will save eight bytes
> > in every structure which embeds it.
> >
> > Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> >
> 
> Is this kind of descriptiveness expected? I am only a sojourner here,
> but even then I suspect I'm going to run into a bunch of other
> trivialities of this sort.

Generally, yes, descriptiveness is expected.  I acknowledge it can
be hard to think of what to say, particularly for a one-line patch.

Specifically, the term "LP64" is rarely used; 64-bit or CONFIG_64BIT is
more common.  It's also uncommon to continue a sentence fragment from
the Subject line into the body.

> fwiw I would avoid the term 'pack' as it suggests the attribute
> "packed", perhaps:
> 
> > Reorder the members of struct maple_tree to avoid holes on 64-bit.
> > The size shrinks from 24 to 16 bytes which will save eight bytes
> > in every structure which embeds it.

Works for me!