From ab6e3d0939bb332d72444a532f0f72e0dfde7b7b Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Fri, 8 Sep 2017 16:11:04 -0700
Subject: mm: soft-dirty: keep soft-dirty bits over thp migration

Soft dirty bit is designed to keep tracked over page migration.  This
patch makes it work in the same manner for thp migration too.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/proc/task_mmu.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

(limited to 'fs/proc')

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 8eec35af32e4..4b21c4e51ce4 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -978,17 +978,22 @@ static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
 {
 	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);
-
-	set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
+	if (pmd_present(pmd)) {
+		/* 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);
+
+		set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
+	} else if (is_migration_entry(pmd_to_swp_entry(pmd))) {
+		pmd = pmd_swp_clear_soft_dirty(pmd);
+		set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
+	}
 }
 #else
 static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
-- 
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