diff options
| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2023-01-11 14:28:49 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-02 22:32:55 -0800 |
| commit | 6eee1a0062298601dfc36bd34517affc4458c43d (patch) | |
| tree | 94516d6c4ec833ebe15234605644a4c70d6f4569 /Documentation/mm | |
| parent | eec20426d48bd7b63c69969a793943ed1a99b731 (diff) | |
| download | linux-6eee1a0062298601dfc36bd34517affc4458c43d.tar.gz | |
doc: clarify refcount section by referring to folios & pages
Include the rename of subpages_mapcount to _nr_pages_mapped.
Link: https://lkml.kernel.org/r/20230111142915.1001531-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/mm')
| -rw-r--r-- | Documentation/mm/transhuge.rst | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/Documentation/mm/transhuge.rst b/Documentation/mm/transhuge.rst index ec3dc5b042260b..03bbd0a1904144 100644 --- a/Documentation/mm/transhuge.rst +++ b/Documentation/mm/transhuge.rst @@ -112,20 +112,20 @@ Refcounts and transparent huge pages Refcounting on THP is mostly consistent with refcounting on other compound pages: - - get_page()/put_page() and GUP operate on head page's ->_refcount. + - get_page()/put_page() and GUP operate on the folio->_refcount. - ->_refcount in tail pages is always zero: get_page_unless_zero() never succeeds on tail pages. - - map/unmap of PMD entry for the whole compound page increment/decrement - ->compound_mapcount, stored in the first tail page of the compound page; - and also increment/decrement ->subpages_mapcount (also in the first tail) - by COMPOUND_MAPPED when compound_mapcount goes from -1 to 0 or 0 to -1. + - map/unmap of a PMD entry for the whole THP increment/decrement + folio->_entire_mapcount and also increment/decrement + folio->_nr_pages_mapped by COMPOUND_MAPPED when _entire_mapcount + goes from -1 to 0 or 0 to -1. - - map/unmap of sub-pages with PTE entry increment/decrement ->_mapcount - on relevant sub-page of the compound page, and also increment/decrement - ->subpages_mapcount, stored in first tail page of the compound page, when - _mapcount goes from -1 to 0 or 0 to -1: counting sub-pages mapped by PTE. + - map/unmap of individual pages with PTE entry increment/decrement + page->_mapcount and also increment/decrement folio->_nr_pages_mapped + when page->_mapcount goes from -1 to 0 or 0 to -1 as this counts + the number of pages mapped by PTE. split_huge_page internally has to distribute the refcounts in the head page to the tail pages before clearing all PG_head/tail bits from the page |