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31a31da8a6
Let's free up some space on 32bit in page[1] by moving the _pincount to page[2]. For order-1 folios (never anon folios!) on 32bit, we will now also use the GUP_PIN_COUNTING_BIAS approach. A fully-mapped order-1 folio requires 2 references. With GUP_PIN_COUNTING_BIAS being 1024, we'd detect such folios as "maybe pinned" with 512 full mappings, instead of 1024 for order-0. As anon folios are out of the picture (which are the most relevant users of checking for pinnings on *mapped* pages) and we are talking about 32bit, this is not expected to cause any trouble. In __dump_page(), copy one additional folio page if we detect a folio with an order > 1, so we can dump the pincount on order > 1 folios reliably. Note that THPs on 32bit are not particularly common (and we don't care too much about performance), but we want to keep it working reliably, because likely we want to use large folios there as well in the future, independent of PMD leaf support. Once we dynamically allocate "struct folio", fortunately the 32bit specifics will likely go away again; even small folios could then have a pincount and folio_has_pincount() would essentially always return "true". Link: https://lkml.kernel.org/r/20250303163014.1128035-6-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Andy Lutomirks^H^Hski <luto@kernel.org> Cc: Borislav Betkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Matthew Wilcow (Oracle) <willy@infradead.org> Cc: Michal Koutn <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: tejun heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
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| usr | ||
| virt | ||
| .clang-format | ||
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| .cocciconfig | ||
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| .get_maintainer.ignore | ||
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| README | ||
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.