linux-kernel - Re: [PATCH v2 09/16] doc: update porting, vfs documentation for mmap

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] [day] [month] [year] [list]

Message-ID: <xbz56k25ftkjbjpjpslqad5b77klaxg3ganckhbnwe3mf6vtpy@3ytagvaq4gk5>
Date: Thu, 11 Sep 2025 10:55:42 +0200
From: Jan Kara <jack@...e.cz>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, 
	Jonathan Corbet <corbet@....net>, Matthew Wilcox <willy@...radead.org>, 
	Guo Ren <guoren@...nel.org>, Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
	Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>, 
	Alexander Gordeev <agordeev@...ux.ibm.com>, Christian Borntraeger <borntraeger@...ux.ibm.com>, 
	Sven Schnelle <svens@...ux.ibm.com>, "David S . Miller" <davem@...emloft.net>, 
	Andreas Larsson <andreas@...sler.com>, Arnd Bergmann <arnd@...db.de>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Dan Williams <dan.j.williams@...el.com>, 
	Vishal Verma <vishal.l.verma@...el.com>, Dave Jiang <dave.jiang@...el.com>, 
	Nicolas Pitre <nico@...xnic.net>, Muchun Song <muchun.song@...ux.dev>, 
	Oscar Salvador <osalvador@...e.de>, David Hildenbrand <david@...hat.com>, 
	Konstantin Komarov <almaz.alexandrovich@...agon-software.com>, Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>, 
	Dave Young <dyoung@...hat.com>, Tony Luck <tony.luck@...el.com>, 
	Reinette Chatre <reinette.chatre@...el.com>, Dave Martin <Dave.Martin@....com>, 
	James Morse <james.morse@....com>, Alexander Viro <viro@...iv.linux.org.uk>, 
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	"Liam R . Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka <vbabka@...e.cz>, 
	Mike Rapoport <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>, 
	Michal Hocko <mhocko@...e.com>, Hugh Dickins <hughd@...gle.com>, 
	Baolin Wang <baolin.wang@...ux.alibaba.com>, Uladzislau Rezki <urezki@...il.com>, 
	Dmitry Vyukov <dvyukov@...gle.com>, Andrey Konovalov <andreyknvl@...il.com>, 
	Jann Horn <jannh@...gle.com>, Pedro Falcato <pfalcato@...e.de>, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-csky@...r.kernel.org, 
	linux-mips@...r.kernel.org, linux-s390@...r.kernel.org, sparclinux@...r.kernel.org, 
	nvdimm@...ts.linux.dev, linux-cxl@...r.kernel.org, linux-mm@...ck.org, 
	ntfs3@...ts.linux.dev, kexec@...ts.infradead.org, kasan-dev@...glegroups.com, 
	Jason Gunthorpe <jgg@...dia.com>
Subject: Re: [PATCH v2 09/16] doc: update porting, vfs documentation for
 mmap_prepare actions

On Wed 10-09-25 21:22:04, Lorenzo Stoakes wrote:
> Now we have introduced the ability to specify that actions should be taken
> after a VMA is established via the vm_area_desc->action field as specified
> in mmap_prepare, update both the VFS documentation and the porting guide to
> describe this.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  Documentation/filesystems/porting.rst | 5 +++++
>  Documentation/filesystems/vfs.rst     | 4 ++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
> index 85f590254f07..6743ed0b9112 100644
> --- a/Documentation/filesystems/porting.rst
> +++ b/Documentation/filesystems/porting.rst
> @@ -1285,3 +1285,8 @@ rather than a VMA, as the VMA at this stage is not yet valid.
>  The vm_area_desc provides the minimum required information for a filesystem
>  to initialise state upon memory mapping of a file-backed region, and output
>  parameters for the file system to set this state.
> +
> +In nearly all cases, this is all that is required for a filesystem. However, if
> +a filesystem needs to perform an operation such a pre-population of page tables,
> +then that action can be specified in the vm_area_desc->action field, which can
> +be configured using the mmap_action_*() helpers.
> diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
> index 486a91633474..9e96c46ee10e 100644
> --- a/Documentation/filesystems/vfs.rst
> +++ b/Documentation/filesystems/vfs.rst
> @@ -1236,6 +1236,10 @@ otherwise noted.
>  	file-backed memory mapping, most notably establishing relevant
>  	private state and VMA callbacks.
>  
> +	If further action such as pre-population of page tables is required,
> +	this can be specified by the vm_area_desc->action field and related
> +	parameters.
> +
>  Note that the file operations are implemented by the specific
>  filesystem in which the inode resides.  When opening a device node
>  (character or block special) most filesystems will call special
> -- 
> 2.51.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR