mm/rmap: fix munlocking Anon THP with mlocked ptes

Many thanks to Kirill for reminding that PageDoubleMap cannot be relied on
to warn of pte mappings in the Anon THP case; and a scan of subpages does
not seem appropriate here.  Note how follow_trans_huge_pmd() does not even
mark an Anon THP as mlocked when compound_mapcount != 1: multiple mlocking
of Anon THP is avoided, so simply return from page_mlock() in this case.

Link: https://lore.kernel.org/lkml/[email protected]/
Fixes: d9770fcc1c0c ("mm/rmap: fix old bug: munlocking THP missed other mlocks")
Reported-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Hugh Dickins <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Shakeel Butt <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions