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Diffstat (limited to 'Documentation/mm')
| -rw-r--r-- | Documentation/mm/transhuge.rst | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/mm/transhuge.rst b/Documentation/mm/transhuge.rst index a2cd8800d527..baa17d718a76 100644 --- a/Documentation/mm/transhuge.rst +++ b/Documentation/mm/transhuge.rst @@ -120,11 +120,19 @@ pages: and also increment/decrement folio->_nr_pages_mapped by ENTIRELY_MAPPED when _entire_mapcount goes from -1 to 0 or 0 to -1. + We also maintain the two slots for tracking MM owners (MM ID and + corresponding mapcount), and the current status ("maybe mapped shared" vs. + "mapped exclusively"). + - map/unmap of individual pages with PTE entry increment/decrement page->_mapcount, increment/decrement folio->_large_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. + We also maintain the two slots for tracking MM owners (MM ID and + corresponding mapcount), and the current status ("maybe mapped shared" vs. + "mapped exclusively"). + 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 structures. It can be done easily for refcounts taken by page table |