The patch titled
Subject: mm: thp: check pmd_trans_unstable() after split_huge_pmd()
has been added to the -mm tree. Its filename is
mm-thp-check-pmd_trans_unstable-after-split_huge_pmd.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-check-pmd_trans_unstable-after-split_huge_pmd.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-check-pmd_trans_unstable-after-split_huge_pmd.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm: thp: check pmd_trans_unstable() after split_huge_pmd()
split_huge_pmd() doesn't guarantee that the pmd is normal pmd pointing to
pte entries, which can be checked with pmd_trans_unstable(). Some callers
make this assertion and some do it differently and some not, so let's do
it in a unified manner.
Link: http://lkml.kernel.org/r/1464741400-12143-1-git-send-email-n-horiguchi@xxxxxxxxxxxxx
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 2 ++
mm/mempolicy.c | 2 ++
mm/mprotect.c | 2 +-
mm/mremap.c | 3 +--
4 files changed, 6 insertions(+), 3 deletions(-)
diff -puN mm/gup.c~mm-thp-check-pmd_trans_unstable-after-split_huge_pmd mm/gup.c
--- a/mm/gup.c~mm-thp-check-pmd_trans_unstable-after-split_huge_pmd
+++ a/mm/gup.c
@@ -279,6 +279,8 @@ struct page *follow_page_mask(struct vm_
spin_unlock(ptl);
ret = 0;
split_huge_pmd(vma, pmd, address);
+ if (pmd_trans_unstable(pmd))
+ ret = -EBUSY;
} else {
get_page(page);
spin_unlock(ptl);
diff -puN mm/mempolicy.c~mm-thp-check-pmd_trans_unstable-after-split_huge_pmd mm/mempolicy.c
--- a/mm/mempolicy.c~mm-thp-check-pmd_trans_unstable-after-split_huge_pmd
+++ a/mm/mempolicy.c
@@ -512,6 +512,8 @@ static int queue_pages_pte_range(pmd_t *
}
}
+ if (pmd_trans_unstable(pmd))
+ return 0;
retry:
pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
for (; addr != end; pte++, addr += PAGE_SIZE) {
diff -puN mm/mprotect.c~mm-thp-check-pmd_trans_unstable-after-split_huge_pmd mm/mprotect.c
--- a/mm/mprotect.c~mm-thp-check-pmd_trans_unstable-after-split_huge_pmd
+++ a/mm/mprotect.c
@@ -163,7 +163,7 @@ static inline unsigned long change_pmd_r
if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE) {
split_huge_pmd(vma, pmd, addr);
- if (pmd_none(*pmd))
+ if (pmd_trans_unstable(pmd))
continue;
} else {
int nr_ptes = change_huge_pmd(vma, pmd, addr,
diff -puN mm/mremap.c~mm-thp-check-pmd_trans_unstable-after-split_huge_pmd mm/mremap.c
--- a/mm/mremap.c~mm-thp-check-pmd_trans_unstable-after-split_huge_pmd
+++ a/mm/mremap.c
@@ -210,9 +210,8 @@ unsigned long move_page_tables(struct vm
}
}
split_huge_pmd(vma, old_pmd, old_addr);
- if (pmd_none(*old_pmd))
+ if (pmd_trans_unstable(old_pmd))
continue;
- VM_BUG_ON(pmd_trans_huge(*old_pmd));
}
if (pte_alloc(new_vma->vm_mm, new_pmd, new_addr))
break;
_
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
mm-thp-check-pmd_trans_unstable-after-split_huge_pmd.patch
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