From: Lorenzo Stoakes <lstoakes@gmail.com>
To: "Liam R. Howlett" <Liam.Howlett@oracle.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>,
maple-tree@lists.infradead.org
Subject: Re: [PATCH 0/4] further cleanup of vma_merge()
Date: Mon, 20 Mar 2023 17:09:41 +0000 [thread overview]
Message-ID: <a52f4521-8d02-496e-ac40-e8da5b1ec268@lucifer.local> (raw)
In-Reply-To: <20230320164707.zpjhcwplkrp4tvgf@revolver>
On Mon, Mar 20, 2023 at 12:47:07PM -0400, Liam R. Howlett wrote:
> * Lorenzo Stoakes <lstoakes@gmail.com> [230318 07:15]:
> > Following on from Vlastimil Babka's patch series "cleanup vma_merge() and
> > improve mergeability tests" which was in turn based on Liam's prior
> > cleanups, this patch series introduces changes discussed in review of
> > Vlastimil's series and goes further in attempting to make the logic as
> > clear as possible.
> >
> > Nearly all of this should have absolutely no functional impact, however it
> > does add a singular VM_WARN_ON() case.
>
> Thanks for looking at this function and adding more clarity. I'm happy
> to have comments within the code, especially tricky areas. But I find
> that adding almost 50 lines to this function makes it rather hard to
> follow.
>
> Can we remove the more obvious comments and possibly reduce the nesting
> of others so there are less lines?
>
> For example in patch 2:
> /*
> * If there is a previous VMA specified, find the next, otherwise find
> * the first.
> */
> vma = find_vma(mm, prev ? prev->vm_end : 0);
>
> Is rather verbose for something that can be seen in the code itself.
>
> I think we are risking over-documenting what is going on here which is
> making the code harder to read; the function is pushing 200 lines now.
>
> >
> > Lorenzo Stoakes (4):
> > mm/mmap/vma_merge: further improve prev/next VMA naming
> > mm/mmap/vma_merge: set next to NULL if not applicable
> > mm/mmap/vma_merge: extend invariants, avoid invalid res, vma
> > mm/mmap/vma_merge: be explicit about the non-mergeable case
> >
> > mm/mmap.c | 165 +++++++++++++++++++++++++++++++++++-------------------
> > 1 file changed, 107 insertions(+), 58 deletions(-)
> >
> > --
> > 2.39.2
>
Sure, I did try not to overdo things (once you start simplifying you can go
too far), but it seems like I _did_ go too far on the commenting (perhaps
pushing too far the other way).
I will simplify, remove things implied by the code and strip down + respin.
prev parent reply other threads:[~2023-03-20 17:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-18 11:13 [PATCH 0/4] further cleanup of vma_merge() Lorenzo Stoakes
2023-03-18 11:13 ` [PATCH 1/4] mm/mmap/vma_merge: further improve prev/next VMA naming Lorenzo Stoakes
2023-03-18 11:13 ` [PATCH 2/4] mm/mmap/vma_merge: set next to NULL if not applicable Lorenzo Stoakes
2023-03-20 14:25 ` Vernon Yang
2023-03-20 14:58 ` Lorenzo Stoakes
2023-03-20 16:27 ` Liam R. Howlett
2023-03-20 17:11 ` Lorenzo Stoakes
2023-03-18 11:13 ` [PATCH 3/4] mm/mmap/vma_merge: extend invariants, avoid invalid res, vma Lorenzo Stoakes
2023-03-18 11:13 ` [PATCH 4/4] mm/mmap/vma_merge: be explicit about the non-mergeable case Lorenzo Stoakes
2023-03-20 16:47 ` [PATCH 0/4] further cleanup of vma_merge() Liam R. Howlett
2023-03-20 17:09 ` Lorenzo Stoakes [this message]
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