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dbf8be8218
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. [lorenzo.stoakes@oracle.com: v3] Link: https://lkml.kernel.org/r/20241114205402.859737-1-lorenzo.stoakes@oracle.com [lorenzo.stoakes@oracle.com: docs/mm: minor corrections] Link: https://lkml.kernel.org/r/d3de735a-25ae-4eb2-866c-a9624fe6f795@lucifer.local [jannh@google.com: docs/mm: add more warnings around page table access] Link: https://lkml.kernel.org/r/20241118-vma-docs-addition1-onv3-v2-1-c9d5395b72ee@google.com Link: https://lkml.kernel.org/r/20241108135708.48567-1-lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Acked-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Reviewed-by: Jann Horn <jannh@google.com> Cc: Alice Ryhl <aliceryhl@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: SeongJae Park <sj@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.