khugepaged: collapse_pte_mapped_thp() flush the right range
pmdp_collapse_flush() should be given the start address at which the huge
page is mapped, haddr: it was given addr, which at that point has been
used as a local variable, incremented to the end address of the extent.
Found by source inspection while chasing a hugepage locking bug, which I
then could not explain by this. At first I thought this was very bad;
then saw that all of the page translations that were not flushed would
actually still point to the right pages afterwards, so harmless; then
realized that I know nothing of how different architectures and models
cache intermediate paging structures, so maybe it matters after all -
particularly since the page table concerned is immediately freed.
Much easier to fix than to think about.
Fixes: 27e1f8273113 ("khugepaged: enable collapse pmd for pte-mapped THP")
Signed-off-by: Hugh Dickins <email@example.com>
Signed-off-by: Andrew Morton <firstname.lastname@example.org>
Acked-by: Kirill A. Shutemov <email@example.com>
Cc: Andrea Arcangeli <firstname.lastname@example.org>
Cc: Mike Kravetz <email@example.com>
Cc: Song Liu <firstname.lastname@example.org>
Cc: <email@example.com> [5.4+]
Signed-off-by: Linus Torvalds <firstname.lastname@example.org>
1 file changed