linux-kernel - Re: [PATCH] mm/huge_memory: refactor after-split (page) cache code.

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Message-ID: <57a80de0-c5f8-4fd9-9b4a-fea97fe6c533@suswa.mountain>
Date: Thu, 17 Jul 2025 22:22:06 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Zi Yan <ziy@...dia.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>,
	Antonio Quartulli <antonio@...delbit.com>, linux-mm@...ck.org,
	Hugh Dickins <hughd@...gle.com>,
	Kirill Shutemov <k.shutemov@...il.com>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Nico Pache <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>,
	Dev Jain <dev.jain@....com>, Barry Song <baohua@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/huge_memory: refactor after-split (page) cache code.

On Thu, Jul 17, 2025 at 11:45:13AM -0400, Zi Yan wrote:
> 
> >>
> >> Since we no longer need to make new_folio->index >= end work for anon
> >> folios, can we drop the end = -1 in the if (is_anon) { ... } branch?
> >
> > Sure.
> 
> A second thought on this one. If I remove end = -1, can static analysis
> tools understand that end is not used when a folio is anonymous?
> Probably, I can initialize end to -1 and remove end = -1 in is_anon
> branch.

Smatch says that "if "mapping" is non-NULL then "end" is initialized"
and it doesn't trigger a warning.  I don't know how the other checkers
handle it.

Btw, the only thing you really have to pay attention to is Clang because
we treat build warnings as failure.  You're always free to ignore other
checkers.

regards,
dan carpenter