thp: fix MADV_DONTNEED vs clear soft dirty race

Yet another instance of the same race.

Fix is identical to change_huge_pmd().

See "thp: fix MADV_DONTNEED vs.  numa balancing race" for more details.

Link: http://lkml.kernel.org/r/20170302151034.27829-5-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f08bd31c1081..312578089544 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -900,7 +900,14 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma,
 static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
                 unsigned long addr, pmd_t *pmdp)
 {
-        pmd_t pmd = pmdp_huge_get_and_clear(vma->vm_mm, addr, pmdp);
+        pmd_t pmd = *pmdp;
+
+        /* See comment in change_huge_pmd() */
+        pmdp_invalidate(vma, addr, pmdp);
+        if (pmd_dirty(*pmdp))
+                pmd = pmd_mkdirty(pmd);
+        if (pmd_young(*pmdp))
+                pmd = pmd_mkyoung(pmd);
 
         pmd = pmd_wrprotect(pmd);
         pmd = pmd_clear_soft_dirty(pmd);