Re: [PATCH v2] docs/mm: add VMA locks documentation

From: Bagas Sanjaya
Date: Tue Nov 12 2024 - 00:39:42 EST


On Fri, Nov 08, 2024 at 01:57:06PM +0000, Lorenzo Stoakes wrote:
> Locking around VMAs is complicated and confusing. While we have a number of
> disparate comments scattered around the place, we seem to be reaching a
> level of complexity that justifies a serious effort at clearly documenting
> how locks are expected to be used when it comes to interacting with
> mm_struct and vm_area_struct objects.
>
> This is especially pertinent as regards the efforts to find sensible
> abstractions for these fundamental objects in kernel rust code whose
> compiler strictly requires some means of expressing these rules (and
> through this expression, self-document these requirements as well as
> enforce them).
>
> The document limits scope to mmap and VMA locks and those that are
> immediately adjacent and relevant to them - so additionally covers page
> table locking as this is so very closely tied to VMA operations (and relies
> upon us handling these correctly).
>
> The document tries to cover some of the nastier and more confusing edge
> cases and concerns especially around lock ordering and page table teardown.
>
> The document is split between generally useful information for users of mm
> interfaces, and separately a section intended for mm kernel developers
> providing a discussion around internal implementation details.
>

The doc LGTM, thanks!

Reviewed-by: Bagas Sanjaya <bagasdotme@xxxxxxxxx>

--
An old man doll... just what I always wanted! - Clara

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