diff --git a/Documentation/vm/soft-dirty.txt b/Documentation/vm/soft-dirty.txt
index 9a12a59..55684d1 100644
--- a/Documentation/vm/soft-dirty.txt
+++ b/Documentation/vm/soft-dirty.txt
@@ -28,6 +28,13 @@
 the kernel does is finds this fact out and puts both writable and soft-dirty
 bits on the PTE.
 
+  While in most cases tracking memory changes by #PF-s is more than enough
+there is still a scenario when we can lose soft dirty bits -- a task
+unmaps a previously mapped memory region and then maps a new one at exactly
+the same place. When unmap is called, the kernel internally clears PTE values
+including soft dirty bits. To notify user space application about such
+memory region renewal the kernel always marks new memory regions (and
+expanded regions) as soft dirty.
 
   This feature is actively used by the checkpoint-restore project. You
 can find more details about it on http://criu.org
diff --git a/fs/exec.c b/fs/exec.c
index fd774c7..2d1e52a5 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -266,7 +266,7 @@
 	BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 	vma->vm_end = STACK_TOP_MAX;
 	vma->vm_start = vma->vm_end - PAGE_SIZE;
-	vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
+	vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 	INIT_LIST_HEAD(&vma->anon_vma_chain);
 
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 107d026..0922863 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -740,6 +740,9 @@
 		ptent = pte_file_clear_soft_dirty(ptent);
 	}
 
+	if (vma->vm_flags & VM_SOFTDIRTY)
+		vma->vm_flags &= ~VM_SOFTDIRTY;
+
 	set_pte_at(vma->vm_mm, addr, pte, ptent);
 #endif
 }
@@ -949,13 +952,15 @@
 		if (is_migration_entry(entry))
 			page = migration_entry_to_page(entry);
 	} else {
-		*pme = make_pme(PM_NOT_PRESENT(pm->v2));
+		if (vma->vm_flags & VM_SOFTDIRTY)
+			flags2 |= __PM_SOFT_DIRTY;
+		*pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, flags2));
 		return;
 	}
 
 	if (page && !PageAnon(page))
 		flags |= PM_FILE;
-	if (pte_soft_dirty(pte))
+	if ((vma->vm_flags & VM_SOFTDIRTY) || pte_soft_dirty(pte))
 		flags2 |= __PM_SOFT_DIRTY;
 
 	*pme = make_pme(PM_PFRAME(frame) | PM_STATUS2(pm->v2, flags2) | flags);
@@ -974,7 +979,7 @@
 		*pme = make_pme(PM_PFRAME(pmd_pfn(pmd) + offset)
 				| PM_STATUS2(pm->v2, pmd_flags2) | PM_PRESENT);
 	else
-		*pme = make_pme(PM_NOT_PRESENT(pm->v2));
+		*pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, pmd_flags2));
 }
 #else
 static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
@@ -997,7 +1002,11 @@
 	if (vma && pmd_trans_huge_lock(pmd, vma) == 1) {
 		int pmd_flags2;
 
-		pmd_flags2 = (pmd_soft_dirty(*pmd) ? __PM_SOFT_DIRTY : 0);
+		if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd))
+			pmd_flags2 = __PM_SOFT_DIRTY;
+		else
+			pmd_flags2 = 0;
+
 		for (; addr != end; addr += PAGE_SIZE) {
 			unsigned long offset;
 
@@ -1015,12 +1024,17 @@
 	if (pmd_trans_unstable(pmd))
 		return 0;
 	for (; addr != end; addr += PAGE_SIZE) {
+		int flags2;
 
 		/* check to see if we've left 'vma' behind
 		 * and need a new, higher one */
 		if (vma && (addr >= vma->vm_end)) {
 			vma = find_vma(walk->mm, addr);
-			pme = make_pme(PM_NOT_PRESENT(pm->v2));
+			if (vma && (vma->vm_flags & VM_SOFTDIRTY))
+				flags2 = __PM_SOFT_DIRTY;
+			else
+				flags2 = 0;
+			pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, flags2));
 		}
 
 		/* check that 'vma' actually covers this address,
@@ -1044,13 +1058,15 @@
 
 #ifdef CONFIG_HUGETLB_PAGE
 static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
-					pte_t pte, int offset)
+					pte_t pte, int offset, int flags2)
 {
 	if (pte_present(pte))
-		*pme = make_pme(PM_PFRAME(pte_pfn(pte) + offset)
-				| PM_STATUS2(pm->v2, 0) | PM_PRESENT);
+		*pme = make_pme(PM_PFRAME(pte_pfn(pte) + offset)	|
+				PM_STATUS2(pm->v2, flags2)		|
+				PM_PRESENT);
 	else
-		*pme = make_pme(PM_NOT_PRESENT(pm->v2));
+		*pme = make_pme(PM_NOT_PRESENT(pm->v2)			|
+				PM_STATUS2(pm->v2, flags2));
 }
 
 /* This function walks within one hugetlb entry in the single call */
@@ -1059,12 +1075,22 @@
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
+	struct vm_area_struct *vma;
 	int err = 0;
+	int flags2;
 	pagemap_entry_t pme;
 
+	vma = find_vma(walk->mm, addr);
+	WARN_ON_ONCE(!vma);
+
+	if (vma && (vma->vm_flags & VM_SOFTDIRTY))
+		flags2 = __PM_SOFT_DIRTY;
+	else
+		flags2 = 0;
+
 	for (; addr != end; addr += PAGE_SIZE) {
 		int offset = (addr & ~hmask) >> PAGE_SHIFT;
-		huge_pte_to_pagemap_entry(&pme, pm, *pte, offset);
+		huge_pte_to_pagemap_entry(&pme, pm, *pte, offset, flags2);
 		err = add_to_pagemap(addr, &pme, pm);
 		if (err)
 			return err;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d2d59b4..dce2456 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -115,6 +115,12 @@
 #define VM_ARCH_1	0x01000000	/* Architecture-specific flag */
 #define VM_DONTDUMP	0x04000000	/* Do not include in the core dump */
 
+#ifdef CONFIG_MEM_SOFT_DIRTY
+# define VM_SOFTDIRTY	0x08000000	/* Not soft dirty clean area */
+#else
+# define VM_SOFTDIRTY	0
+#endif
+
 #define VM_MIXEDMAP	0x10000000	/* Can contain "struct page" and pure PFN pages */
 #define VM_HUGEPAGE	0x20000000	/* MADV_HUGEPAGE marked this vma */
 #define VM_NOHUGEPAGE	0x40000000	/* MADV_NOHUGEPAGE marked this vma */
diff --git a/mm/mmap.c b/mm/mmap.c
index 13926a5..51958d1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1609,6 +1609,15 @@
 	if (file)
 		uprobe_mmap(vma);
 
+	/*
+	 * New (or expanded) vma always get soft dirty status.
+	 * Otherwise user-space soft-dirty page tracker won't
+	 * be able to distinguish situation when vma area unmapped,
+	 * then new mapped in-place (which must be aimed as
+	 * a completely new data area).
+	 */
+	vma->vm_flags |= VM_SOFTDIRTY;
+
 	return addr;
 
 unmap_and_free_vma:
@@ -2652,6 +2661,7 @@
 	mm->total_vm += len >> PAGE_SHIFT;
 	if (flags & VM_LOCKED)
 		mm->locked_vm += (len >> PAGE_SHIFT);
+	vma->vm_flags |= VM_SOFTDIRTY;
 	return addr;
 }
 
@@ -2916,7 +2926,7 @@
 	vma->vm_start = addr;
 	vma->vm_end = addr + len;
 
-	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
+	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
 	vma->vm_ops = &special_mapping_vmops;