diff options
| author | Mel Gorman <mgorman@suse.de> | 2014-10-02 19:47:42 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-10-09 12:18:42 -0700 |
| commit | f35407acce23bab3727190a94468362dc8f030a1 (patch) | |
| tree | df90e326cd363fee8ba9a2b050f86ca374aaee91 /mm | |
| parent | 183c062c51c7e7663752b94ac399c830e4cb3c44 (diff) | |
mm: numa: Do not mark PTEs pte_numa when splitting huge pages
commit abc40bd2eeb77eb7c2effcaf63154aad929a1d5f upstream.
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.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/huge_memory.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b9a096a36edc..d21c9ef0943c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1740,14 +1740,17 @@ static int __split_huge_page_map(struct page *page, for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { pte_t *pte, entry; BUG_ON(PageCompound(page+i)); + /* + * Note that pmd_numa is not transferred deliberately + * to avoid any possibility that pte_numa leaks to + * a PROT_NONE VMA by accident. + */ entry = mk_pte(page + i, vma->vm_page_prot); entry = maybe_mkwrite(pte_mkdirty(entry), vma); if (!pmd_write(*pmd)) entry = pte_wrprotect(entry); if (!pmd_young(*pmd)) entry = pte_mkold(entry); - if (pmd_numa(*pmd)) - entry = pte_mknuma(entry); pte = pte_offset_map(&_pmd, haddr); BUG_ON(!pte_none(*pte)); set_pte_at(mm, haddr, pte, entry); |