mm: numa: Do not mark PTEs pte_numa when splitting huge pages
This patch reverts 1ba6e0b50b ("mm: numa: split_huge_page: transfer the
NUMA type from the pmd to the pte"). If a huge page is being split due
a protection change and the tail will be in a PROT_NONE vma then NUMA
hinting PTEs are temporarily created in the protected VMA.
In the specific case above, it should get fixed up by change_pte_range()
but there is a window of opportunity for weirdness to happen. Similarly,
if a huge page is shrunk and split during a protection update but before
pmd_numa is cleared then a pte_numa can be left behind.
Instead of adding complexity trying to deal with the case, this patch
will not mark PTEs NUMA when splitting a huge page. NUMA hinting faults
will not be triggered which is marginal in comparison to the complexity
in dealing with the corner cases during THP split.
Signed-off-by: Mel Gorman <email@example.com>
Acked-by: Rik van Riel <firstname.lastname@example.org>
Acked-by: Kirill A. Shutemov <email@example.com>
Signed-off-by: Linus Torvalds <firstname.lastname@example.org>
1 file changed