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Subject[PATCHv10 01/36] mm, proc: adjust PSS calculation
Date
With new refcounting all subpages of the compound page are not necessary
have the same mapcount. We need to take into account mapcount of every
sub-page.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
fs/proc/task_mmu.c | 47 +++++++++++++++++++++++++++++++----------------
1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 66954f5d753c..6b73be84271c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -453,9 +453,10 @@ struct mem_size_stats {
};

static void smaps_account(struct mem_size_stats *mss, struct page *page,
- unsigned long size, bool young, bool dirty)
+ bool compound, bool young, bool dirty)
{
- int mapcount;
+ int i, nr = compound ? HPAGE_PMD_NR : 1;
+ unsigned long size = nr * PAGE_SIZE;

if (PageAnon(page))
mss->anonymous += size;
@@ -464,23 +465,37 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page,
/* Accumulate the size in pages that have been accessed. */
if (young || page_is_young(page) || PageReferenced(page))
mss->referenced += size;
- mapcount = page_mapcount(page);
- if (mapcount >= 2) {
- u64 pss_delta;

- if (dirty || PageDirty(page))
- mss->shared_dirty += size;
- else
- mss->shared_clean += size;
- pss_delta = (u64)size << PSS_SHIFT;
- do_div(pss_delta, mapcount);
- mss->pss += pss_delta;
- } else {
+ /*
+ * page_count(page) == 1 guarantees the page is mapped exactly once.
+ * If any subpage of the compound page mapped with PTE it would elevate
+ * page_count().
+ */
+ if (page_count(page) == 1) {
if (dirty || PageDirty(page))
mss->private_dirty += size;
else
mss->private_clean += size;
mss->pss += (u64)size << PSS_SHIFT;
+ return;
+ }
+
+ for (i = 0; i < nr; i++, page++) {
+ int mapcount = page_mapcount(page);
+
+ if (mapcount >= 2) {
+ if (dirty || PageDirty(page))
+ mss->shared_dirty += PAGE_SIZE;
+ else
+ mss->shared_clean += PAGE_SIZE;
+ mss->pss += (PAGE_SIZE << PSS_SHIFT) / mapcount;
+ } else {
+ if (dirty || PageDirty(page))
+ mss->private_dirty += PAGE_SIZE;
+ else
+ mss->private_clean += PAGE_SIZE;
+ mss->pss += PAGE_SIZE << PSS_SHIFT;
+ }
}
}

@@ -515,7 +530,8 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,

if (!page)
return;
- smaps_account(mss, page, PAGE_SIZE, pte_young(*pte), pte_dirty(*pte));
+
+ smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte));
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -531,8 +547,7 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
if (IS_ERR_OR_NULL(page))
return;
mss->anonymous_thp += HPAGE_PMD_SIZE;
- smaps_account(mss, page, HPAGE_PMD_SIZE,
- pmd_young(*pmd), pmd_dirty(*pmd));
+ smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd));
}
#else
static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
--
2.5.0


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