Although pmd_present() might seem to indicate a valid and mapped pmd entry, in reality it returns true when pmd_page() points to a valid page in memory , regardless whether the pmd entry is mapped or not. Andrea Arcangeli had earlier explained [1] the required semantics for pmd_present(). This just updates the documentation for pmd_present() as required. [1] https://lore.kernel.org/lkml/20181017020930.GN30832@xxxxxxxxxx/ Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxx> Cc: linux-mm@xxxxxxxxx Cc: linux-doc@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> --- This applies on v6.1-rc6 The latest trigger was from an earlier discussion here. https://lore.kernel.org/all/53c0c955-7afe-905b-468a-cd7ac81238c5@xxxxxxx/ Documentation/mm/arch_pgtable_helpers.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/mm/arch_pgtable_helpers.rst b/Documentation/mm/arch_pgtable_helpers.rst index cbaee9e59241..fd2a19df884e 100644 --- a/Documentation/mm/arch_pgtable_helpers.rst +++ b/Documentation/mm/arch_pgtable_helpers.rst @@ -94,7 +94,7 @@ PMD Page Table Helpers +---------------------------+--------------------------------------------------+ | pmd_trans_huge | Tests a Transparent Huge Page (THP) at PMD | +---------------------------+--------------------------------------------------+ -| pmd_present | Tests a valid mapped PMD | +| pmd_present | Tests whether pmd_page() points to valid memory | +---------------------------+--------------------------------------------------+ | pmd_young | Tests a young PMD | +---------------------------+--------------------------------------------------+ -- 2.25.1
