From: Mel Gorman Date: Thu, 2 Oct 2014 18:47:42 +0000 (+0100) Subject: mm: numa: Do not mark PTEs pte_numa when splitting huge pages X-Git-Tag: fixes-for-v3.18-merge-window~51^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=abc40bd2eeb77eb7c2effcaf63154aad929a1d5f;p=pandora-kernel.git 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. VM_RW|VM_PROTNONE |-----------------| ^ split here 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. Cc: stable@vger.kernel.org Signed-off-by: Mel Gorman Acked-by: Rik van Riel Acked-by: Kirill A. Shutemov Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed