mm: proc: smaps_rollup: fix pss_locked calculation

The 'pss_locked' field of smaps_rollup was being calculated incorrectly.
It accumulated the current pss everytime a locked VMA was found.  Fix
that by adding to 'pss_locked' the same time as that of 'pss' if the vma
being walked is locked.

Link: http://lkml.kernel.org/r/20190203065425.14650-1-sspatil@android.com
Fixes: 493b0e9d945f ("mm: add /proc/pid/smaps_rollup")
Signed-off-by: Sandeep Patil <sspatil@android.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: <stable@vger.kernel.org>	[4.14.x, 4.19.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 8 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f0ec9edab2f3..85b0ef890b28 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -423,7 +423,7 @@ struct mem_size_stats {
 };
 
 static void smaps_account(struct mem_size_stats *mss, struct page *page,
-                bool compound, bool young, bool dirty)
+                bool compound, bool young, bool dirty, bool locked)
 {
         int i, nr = compound ? 1 << compound_order(page) : 1;
         unsigned long size = nr * PAGE_SIZE;
@@ -450,24 +450,31 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page,
                 else
                         mss->private_clean += size;
                 mss->pss += (u64)size << PSS_SHIFT;
+                if (locked)
+                        mss->pss_locked += (u64)size << PSS_SHIFT;
                 return;
         }
 
         for (i = 0; i < nr; i++, page++) {
                 int mapcount = page_mapcount(page);
+                unsigned long pss = (PAGE_SIZE << PSS_SHIFT);
 
                 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;
+                        mss->pss += pss / mapcount;
+                        if (locked)
+                                mss->pss_locked += pss / mapcount;
                 } else {
                         if (dirty || PageDirty(page))
                                 mss->private_dirty += PAGE_SIZE;
                         else
                                 mss->private_clean += PAGE_SIZE;
-                        mss->pss += PAGE_SIZE << PSS_SHIFT;
+                        mss->pss += pss;
+                        if (locked)
+                                mss->pss_locked += pss;
                 }
         }
 }
@@ -490,6 +497,7 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,
 {
         struct mem_size_stats *mss = walk->private;
         struct vm_area_struct *vma = walk->vma;
+        bool locked = !!(vma->vm_flags & VM_LOCKED);
         struct page *page = NULL;
 
         if (pte_present(*pte)) {
@@ -532,7 +540,7 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,
         if (!page)
                 return;
 
-        smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte));
+        smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte), locked);
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -541,6 +549,7 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
 {
         struct mem_size_stats *mss = walk->private;
         struct vm_area_struct *vma = walk->vma;
+        bool locked = !!(vma->vm_flags & VM_LOCKED);
         struct page *page;
 
         /* FOLL_DUMP will return -EFAULT on huge zero page */
@@ -555,7 +564,7 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
                 /* pass */;
         else
                 VM_BUG_ON_PAGE(1, page);
-        smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd));
+        smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd), locked);
 }
 #else
 static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
@@ -737,11 +746,8 @@ static void smap_gather_stats(struct vm_area_struct *vma,
                 }
         }
 #endif
-
         /* mmap_sem is held in m_start */
         walk_page_vma(vma, &smaps_walk);
-        if (vma->vm_flags & VM_LOCKED)
-                mss->pss_locked += mss->pss;
 }
 
 #define SEQ_PUT_DEC(str, val) \