[PATCH v4 3/5] pagemap: rework hugetlb and thp report

Konstantin Khlebnikov
2015-07-14T15:38:33Z

This patch moves pmd dissection out of reporting loop: huge pages
are reported as bunch of normal pages with contiguous PFNs.

Add missing "FILE" bit in hugetlb vmas.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
fs/proc/task_mmu.c | 100 +++++++++++++++++++++++-----------------------------
1 file changed, 44 insertions(+), 56 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index c05db6acdc35..040721fa405a 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1038,33 +1038,7 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
return make_pme(frame, flags);
}

-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-static pagemap_entry_t thp_pmd_to_pagemap_entry(struct pagemapread *pm,
- pmd_t pmd, int offset, u64 flags)
-{
- u64 frame = 0;
-
- /*
- * Currently pmd 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 (pmd_present(pmd)) {
- frame = pmd_pfn(pmd) + offset;
- flags |= PM_PRESENT;
- }
-
- return make_pme(frame, flags);
-}
-#else
-static pagemap_entry_t thp_pmd_to_pagemap_entry(struct pagemapread *pm,
- pmd_t pmd, int offset, u64 flags)
-{
- return make_pme(0, 0);
-}
-#endif
-
-static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->vma;
@@ -1073,35 +1047,48 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
pte_t *pte, *orig_pte;
int err = 0;

- if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
- u64 flags = 0;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ if (pmd_trans_huge_lock(pmdp, vma, &ptl) == 1) {
+ u64 flags = 0, frame = 0;
+ pmd_t pmd = *pmdp;

- if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd))
+ if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(pmd))
flags |= PM_SOFT_DIRTY;

+ /*
+ * Currently pmd 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 (pmd_present(pmd)) {
+ flags |= PM_PRESENT;
+ frame = pmd_pfn(pmd) +
+ ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+ }
+
for (; addr != end; addr += PAGE_SIZE) {
- unsigned long offset;
- pagemap_entry_t pme;
+ pagemap_entry_t pme = make_pme(frame, flags);

- offset = (addr & ~PAGEMAP_WALK_MASK) >>
- PAGE_SHIFT;
- pme = thp_pmd_to_pagemap_entry(pm, *pmd, offset, flags);
err = add_to_pagemap(addr, &pme, pm);
if (err)
break;
+ if (flags & PM_PRESENT)
+ frame++;
}
spin_unlock(ptl);
return err;
}

- if (pmd_trans_unstable(pmd))
+ if (pmd_trans_unstable(pmdp))
return 0;
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

/*
* We can assume that @vma always points to a valid one and @end never
* goes beyond vma->vm_end.
*/
- orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ orig_pte = pte = pte_offset_map_lock(walk->mm, pmdp, addr, &ptl);
for (; addr < end; pte++, addr += PAGE_SIZE) {
pagemap_entry_t pme;

@@ -1118,39 +1105,40 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
}

#ifdef CONFIG_HUGETLB_PAGE
-static pagemap_entry_t huge_pte_to_pagemap_entry(struct pagemapread *pm,
- pte_t pte, int offset, u64 flags)
-{
- u64 frame = 0;
-
- if (pte_present(pte)) {
- frame = pte_pfn(pte) + offset;
- flags |= PM_PRESENT;
- }
-
- return make_pme(frame, flags);
-}
-
/* This function walks within one hugetlb entry in the single call */
-static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
+static int pagemap_hugetlb_range(pte_t *ptep, unsigned long hmask,
unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
struct pagemapread *pm = walk->private;
struct vm_area_struct *vma = walk->vma;
+ u64 flags = 0, frame = 0;
int err = 0;
- u64 flags = 0;
- pagemap_entry_t pme;
+ pte_t pte;

if (vma->vm_flags & VM_SOFTDIRTY)
flags |= PM_SOFT_DIRTY;

+ pte = huge_ptep_get(ptep);
+ if (pte_present(pte)) {
+ struct page *page = pte_page(pte);
+
+ if (!PageAnon(page))
+ flags |= PM_FILE;
+
+ flags |= PM_PRESENT;
+ frame = pte_pfn(pte) +
+ ((addr & ~hmask) >> PAGE_SHIFT);
+ }
+
for (; addr != end; addr += PAGE_SIZE) {
- int offset = (addr & ~hmask) >> PAGE_SHIFT;
- pme = huge_pte_to_pagemap_entry(pm, *pte, offset, flags);
+ pagemap_entry_t pme = make_pme(frame, flags);
+
err = add_to_pagemap(addr, &pme, pm);
if (err)
return err;
+ if (flags & PM_PRESENT)
+ frame++;
}

cond_resched();
@@ -1214,7 +1202,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
if (!pm.buffer)
goto out_mm;

- pagemap_walk.pmd_entry = pagemap_pte_range;
+ pagemap_walk.pmd_entry = pagemap_pmd_range;
pagemap_walk.pte_hole = pagemap_pte_hole;
#ifdef CONFIG_HUGETLB_PAGE
pagemap_walk.hugetlb_entry = pagemap_hugetlb_range;