1 files changed, 42 insertions, 5 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 39d641292579..a18e065c1c3e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -11,6 +11,7 @@
 #include <linux/rmap.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
+#include <linux/mmu_notifier.h>
 
 #include <asm/elf.h>
 #include <asm/uaccess.h>
@@ -692,13 +693,32 @@ enum clear_refs_types {
         CLEAR_REFS_ALL = 1,
         CLEAR_REFS_ANON,
         CLEAR_REFS_MAPPED,
+        CLEAR_REFS_SOFT_DIRTY,
         CLEAR_REFS_LAST,
 };
 
 struct clear_refs_private {
         struct vm_area_struct *vma;
+        enum clear_refs_types type;
 };
 
+static inline void clear_soft_dirty(struct vm_area_struct *vma,
+                unsigned long addr, pte_t *pte)
+{
+#ifdef CONFIG_MEM_SOFT_DIRTY
+        /*
+         * The soft-dirty tracker uses #PF-s to catch writes
+         * to pages, so write-protect the pte as well. See the
+         * Documentation/vm/soft-dirty.txt for full description
+         * of how soft-dirty works.
+         */
+        pte_t ptent = *pte;
+        ptent = pte_wrprotect(ptent);
+        ptent = pte_clear_flags(ptent, _PAGE_SOFT_DIRTY);
+        set_pte_at(vma->vm_mm, addr, pte, ptent);
+#endif
+}
+
 static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
                                 unsigned long end, struct mm_walk *walk)
 {
@@ -718,6 +738,11 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
                 if (!pte_present(ptent))
                         continue;
 
+                if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
+                        clear_soft_dirty(vma, addr, pte);
+                        continue;
+                }
+
                 page = vm_normal_page(vma, addr, ptent);
                 if (!page)
                         continue;
@@ -759,6 +784,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
         mm = get_task_mm(task);
         if (mm) {
                 struct clear_refs_private cp = {
+                        .type = type,
                 };
                 struct mm_walk clear_refs_walk = {
                         .pmd_entry = clear_refs_pte_range,
@@ -766,6 +792,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                         .private = &cp,
                 };
                 down_read(&mm->mmap_sem);
+                if (type == CLEAR_REFS_SOFT_DIRTY)
+                        mmu_notifier_invalidate_range_start(mm, 0, -1);
                 for (vma = mm->mmap; vma; vma = vma->vm_next) {
                         cp.vma = vma;
                         if (is_vm_hugetlb_page(vma))
@@ -786,6 +814,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                         walk_page_range(vma->vm_start, vma->vm_end,
                                         &clear_refs_walk);
                 }
+                if (type == CLEAR_REFS_SOFT_DIRTY)
+                        mmu_notifier_invalidate_range_end(mm, 0, -1);
                 flush_tlb_mm(mm);
                 up_read(&mm->mmap_sem);
                 mmput(mm);
@@ -827,6 +857,7 @@ struct pagemapread {
 /* in "new" pagemap pshift bits are occupied with more status bits */
 #define PM_STATUS2(v2, x)   (__PM_PSHIFT(v2 ? x : PAGE_SHIFT))
 
+#define __PM_SOFT_DIRTY      (1LL)
 #define PM_PRESENT          PM_STATUS(4LL)
 #define PM_SWAP             PM_STATUS(2LL)
 #define PM_FILE             PM_STATUS(1LL)
@@ -868,6 +899,7 @@ static void pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
 {
         u64 frame, flags;
         struct page *page = NULL;
+        int flags2 = 0;
 
         if (pte_present(pte)) {
                 frame = pte_pfn(pte);
@@ -888,13 +920,15 @@ static void pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
 
         if (page && !PageAnon(page))
                 flags |= PM_FILE;
+        if (pte_soft_dirty(pte))
+                flags2 |= __PM_SOFT_DIRTY;
 
-        *pme = make_pme(PM_PFRAME(frame) | PM_STATUS2(pm->v2, 0) | flags);
+        *pme = make_pme(PM_PFRAME(frame) | PM_STATUS2(pm->v2, flags2) | flags);
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
-                                        pmd_t pmd, int offset)
+                pmd_t pmd, int offset, int pmd_flags2)
 {
         /*
          * Currently pmd for thp is always present because thp can not be
@@ -903,13 +937,13 @@ static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *p
          */
         if (pmd_present(pmd))
                 *pme = make_pme(PM_PFRAME(pmd_pfn(pmd) + offset)
-                                | PM_STATUS2(pm->v2, 0) | PM_PRESENT);
+                                | PM_STATUS2(pm->v2, pmd_flags2) | PM_PRESENT);
         else
                 *pme = make_pme(PM_NOT_PRESENT(pm->v2));
 }
 #else
 static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm,
-                                                pmd_t pmd, int offset)
+                pmd_t pmd, int offset, int pmd_flags2)
 {
 }
 #endif
@@ -926,12 +960,15 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
         /* find the first VMA at or above 'addr' */
         vma = find_vma(walk->mm, addr);
         if (vma && pmd_trans_huge_lock(pmd, vma) == 1) {
+                int pmd_flags2;
+
+                pmd_flags2 = (pmd_soft_dirty(*pmd) ? __PM_SOFT_DIRTY : 0);
                 for (; addr != end; addr += PAGE_SIZE) {
                         unsigned long offset;
 
                         offset = (addr & ~PAGEMAP_WALK_MASK) >>
                                         PAGE_SHIFT;
-                        thp_pmd_to_pagemap_entry(&pme, pm, *pmd, offset);
+                        thp_pmd_to_pagemap_entry(&pme, pm, *pmd, offset, pmd_flags2);
                         err = add_to_pagemap(addr, &pme, pm);
                         if (err)
                                 break;