[PATCH v5 06/14] procfs: Add support for PUDs to smaps, clear_refs and pagemap

From: Matthew Wilcox
Date: Thu Mar 10 2016 - 19:01:34 EST


From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>

Because there's no 'struct page' for DAX THPs, a lot of this code is
simpler than the PMD code it mimics. Extra code would need to be added
to support PUDs of anonymous or page-cache THPs.

Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 109 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 9df4316..197f37d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -586,6 +586,33 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
}
#endif

+static int smaps_pud_range(pud_t *pud, unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+ struct vm_area_struct *vma = walk->vma;
+ struct mem_size_stats *mss = walk->private;
+
+ if (is_huge_zero_pud(*pud))
+ return 0;
+
+ mss->resident += HPAGE_PUD_SIZE;
+ if (vma->vm_flags & VM_SHARED) {
+ if (pud_dirty(*pud))
+ mss->shared_dirty += HPAGE_PUD_SIZE;
+ else
+ mss->shared_clean += HPAGE_PUD_SIZE;
+ } else {
+ if (pud_dirty(*pud))
+ mss->private_dirty += HPAGE_PUD_SIZE;
+ else
+ mss->private_clean += HPAGE_PUD_SIZE;
+ }
+#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+
+ return 0;
+}
+
static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
@@ -720,6 +747,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
struct vm_area_struct *vma = v;
struct mem_size_stats mss;
struct mm_walk smaps_walk = {
+ .pud_entry = smaps_pud_range,
.pmd_entry = smaps_pte_range,
#ifdef CONFIG_HUGETLB_PAGE
.hugetlb_entry = smaps_hugetlb_range,
@@ -903,13 +931,50 @@ static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,

set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
}
+static inline void clear_soft_dirty_pud(struct vm_area_struct *vma,
+ unsigned long addr, pud_t *pudp)
+{
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+ pud_t pud = pudp_huge_get_and_clear(vma->vm_mm, addr, pudp);
+
+ pud = pud_wrprotect(pud);
+ pud = pud_clear_soft_dirty(pud);
+
+ if (vma->vm_flags & VM_SOFTDIRTY)
+ vma->vm_flags &= ~VM_SOFTDIRTY;
+
+ set_pud_at(vma->vm_mm, addr, pudp, pud);
+#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+}
#else
static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
unsigned long addr, pmd_t *pmdp)
{
}
+static inline void clear_soft_dirty_pud(struct vm_area_struct *vma,
+ unsigned long addr, pud_t *pudp)
+{
+}
#endif

+static int clear_refs_pud_range(pud_t *pud, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
+{
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+ struct clear_refs_private *cp = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+
+ if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
+ clear_soft_dirty_pud(vma, addr, pud);
+ } else {
+ /* Clear accessed and referenced bits. */
+ pudp_test_and_clear_young(vma, addr, pud);
+ }
+#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+
+ return 0;
+}
+
static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
@@ -1020,6 +1085,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
.type = type,
};
struct mm_walk clear_refs_walk = {
+ .pud_entry = clear_refs_pud_range,
.pmd_entry = clear_refs_pte_range,
.test_walk = clear_refs_test_walk,
.mm = mm,
@@ -1184,6 +1250,48 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
return make_pme(frame, flags);
}

+static int pagemap_pud_range(pud_t *pudp, unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+ int err = 0;
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+ struct vm_area_struct *vma = walk->vma;
+ struct pagemapread *pm = walk->private;
+ u64 flags = 0, frame = 0;
+ pud_t pud = *pudp;
+
+ if ((vma->vm_flags & VM_SOFTDIRTY) || pud_soft_dirty(pud))
+ flags |= PM_SOFT_DIRTY;
+
+ /*
+ * Currently pud for thp is always present because thp
+ * can not be swapped-out, migrated, or HWPOISONed
+ * (split in such cases instead.)
+ * This if-check is just to prepare for future implementation.
+ */
+ if (pud_present(pud)) {
+ flags |= PM_PRESENT;
+ if (!(vma->vm_flags & VM_SHARED))
+ flags |= PM_MMAP_EXCLUSIVE;
+
+ if (pm->show_pfn)
+ frame = pud_pfn(pud) +
+ ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+
+ for (; addr != end; addr += PAGE_SIZE) {
+ pagemap_entry_t pme = make_pme(frame, flags);
+
+ err = add_to_pagemap(addr, &pme, pm);
+ if (err)
+ break;
+ if (pm->show_pfn && (flags & PM_PRESENT))
+ frame++;
+ }
+ }
+#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+ return err;
+}
+
static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
@@ -1363,6 +1471,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
if (!pm.buffer)
goto out_mm;

+ pagemap_walk.pud_entry = pagemap_pud_range;
pagemap_walk.pmd_entry = pagemap_pmd_range;
pagemap_walk.pte_hole = pagemap_pte_hole;
#ifdef CONFIG_HUGETLB_PAGE
--
2.7.0