proc/smaps: show amount of nonlinear ptes in vma

Currently, nonlinear mappings can not be distinguished from ordinary
mappings.  This patch adds into /proc/pid/smaps line "Nonlinear: <size>
kB", where size is amount of nonlinear ptes in vma, this line appears only
if VM_NONLINEAR is set.  This information may be useful not only for
checkpoint/restore project.

Requested by Pavel Emelyanov.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e2c1155ac09a..4540b8f76f16 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -393,6 +393,7 @@ struct mem_size_stats {
         unsigned long anonymous;
         unsigned long anonymous_thp;
         unsigned long swap;
+        unsigned long nonlinear;
         u64 pss;
 };
 
@@ -402,6 +403,7 @@ static void smaps_pte_entry(pte_t ptent, unsigned long addr,
 {
         struct mem_size_stats *mss = walk->private;
         struct vm_area_struct *vma = mss->vma;
+        pgoff_t pgoff = linear_page_index(vma, addr);
         struct page *page = NULL;
         int mapcount;
 
@@ -414,6 +416,9 @@ static void smaps_pte_entry(pte_t ptent, unsigned long addr,
                         mss->swap += ptent_size;
                 else if (is_migration_entry(swpent))
                         page = migration_entry_to_page(swpent);
+        } else if (pte_file(ptent)) {
+                if (pte_to_pgoff(ptent) != pgoff)
+                        mss->nonlinear += ptent_size;
         }
 
         if (!page)
@@ -422,6 +427,9 @@ static void smaps_pte_entry(pte_t ptent, unsigned long addr,
         if (PageAnon(page))
                 mss->anonymous += ptent_size;
 
+        if (page->index != pgoff)
+                mss->nonlinear += ptent_size;
+
         mss->resident += ptent_size;
         /* Accumulate the size in pages that have been accessed. */
         if (pte_young(ptent) || PageReferenced(page))
@@ -523,6 +531,10 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
                    (vma->vm_flags & VM_LOCKED) ?
                         (unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);
 
+        if (vma->vm_flags & VM_NONLINEAR)
+                seq_printf(m, "Nonlinear:      %8lu kB\n",
+                                mss.nonlinear >> 10);
+
         if (m->count < m->size)  /* vma is copied successfully */
                 m->version = (vma != get_gate_vma(task->mm))
                         ? vma->vm_start : 0;