linux-kernel - Re: [PATCH 02/16] mm: introduce leaf entry type and use to simplify leaf entry logic

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aQugI-F_Jig41FR9@casper.infradead.org>
Date: Wed, 5 Nov 2025 19:06:11 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Janosch Frank <frankja@...ux.ibm.com>,
	Claudio Imbrenda <imbrenda@...ux.ibm.com>,
	David Hildenbrand <david@...hat.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>, Peter Xu <peterx@...hat.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	Arnd Bergmann <arnd@...db.de>, Zi Yan <ziy@...dia.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>,
	Lance Yang <lance.yang@...ux.dev>,
	Muchun Song <muchun.song@...ux.dev>,
	Oscar Salvador <osalvador@...e.de>,
	Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>,
	Matthew Brost <matthew.brost@...el.com>,
	Joshua Hahn <joshua.hahnjy@...il.com>, Rakie Kim <rakie.kim@...com>,
	Byungchul Park <byungchul@...com>,
	Gregory Price <gourry@...rry.net>,
	Ying Huang <ying.huang@...ux.alibaba.com>,
	Alistair Popple <apopple@...dia.com>,
	Axel Rasmussen <axelrasmussen@...gle.com>,
	Yuanchu Xie <yuanchu@...gle.com>, Wei Xu <weixugc@...gle.com>,
	Kemeng Shi <shikemeng@...weicloud.com>,
	Kairui Song <kasong@...cent.com>, Nhat Pham <nphamcs@...il.com>,
	Baoquan He <bhe@...hat.com>, Chris Li <chrisl@...nel.org>,
	SeongJae Park <sj@...nel.org>, Jason Gunthorpe <jgg@...pe.ca>,
	Leon Romanovsky <leon@...nel.org>, Xu Xin <xu.xin16@....com.cn>,
	Chengming Zhou <chengming.zhou@...ux.dev>,
	Jann Horn <jannh@...gle.com>, Miaohe Lin <linmiaohe@...wei.com>,
	Naoya Horiguchi <nao.horiguchi@...il.com>,
	Pedro Falcato <pfalcato@...e.de>,
	Pasha Tatashin <pasha.tatashin@...een.com>,
	Rik van Riel <riel@...riel.com>, Harry Yoo <harry.yoo@...cle.com>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, linux-s390@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
	linux-arch@...r.kernel.org, damon@...ts.linux.dev
Subject: Re: [PATCH 02/16] mm: introduce leaf entry type and use to simplify
 leaf entry logic

On Mon, Nov 03, 2025 at 12:31:43PM +0000, Lorenzo Stoakes wrote:
> The kernel maintains leaf page table entries which contain either:
> 
> - Nothing ('none' entries)
> - Present entries (that is stuff the hardware can navigate without fault)
> - Everything else that will cause a fault which the kernel handles

The problem is that we're already using 'pmd leaf entries' to mean "this
is a pointer to a PMD entry rather than a table of PTEs".  So I think
we need a new name.  A boring name would be 'swent' (software entry).
An acronym would be SWE.  In the XArray I distinguish between pointer
entries and value entries -- would calling them value entries work here?
Or we could call them something entirely different.  Say 'twig'.  Or
'cask'.