From 337d9abf1cd1a59645d91b6d0b1685a476b81978 Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Tue, 26 Jul 2016 15:24:03 -0700
Subject: [PATCH] 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@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/gup.c | 2 ++
mm/mempolicy.c | 2 ++
mm/mprotect.c | 2 +-
mm/mremap.c | 3 +--
4 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index c057784c84445..dee142e100f4c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -279,6 +279,8 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
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 --git a/mm/mempolicy.c b/mm/mempolicy.c
index 297d6854f8492..fe90e5051012a 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -512,6 +512,8 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
}
}
+ 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 --git a/mm/mprotect.c b/mm/mprotect.c
index 5019a1ef28484..a4830f0325fe2 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -163,7 +163,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
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 --git a/mm/mremap.c b/mm/mremap.c
index 1f157adfdaf9e..da22ad2a56782 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -210,9 +210,8 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
}
}
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;
--
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