[PATCH] Export amount of anonymous memory in a mapping via smaps

[Nikanth Karthikesan <knikanth@suse.de>]

Export the number of anonymous pages in a mapping via smaps.

Even the private pages in a mapping backed by a file, would be marked as
anonymous, when they are modified. Export this information to user-space via
smaps.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>

---

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 439fc1f..3c18fc8 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -326,6 +326,7 @@ struct mem_size_stats {
 	unsigned long private_clean;
 	unsigned long private_dirty;
 	unsigned long referenced;
+	unsigned long anonymous;
 	unsigned long swap;
 	u64 pss;
 };
@@ -356,6 +357,9 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		if (!page)
 			continue;
 
+		if (PageAnon(page))
+			mss->anonymous += PAGE_SIZE;
+
 		mss->resident += PAGE_SIZE;
 		/* Accumulate the size in pages that have been accessed. */
 		if (pte_young(ptent) || PageReferenced(page))
@@ -409,6 +413,7 @@ static int show_smap(struct seq_file *m, void *v)
 		   "Private_Clean:  %8lu kB\n"
 		   "Private_Dirty:  %8lu kB\n"
 		   "Referenced:     %8lu kB\n"
+		   "Anonymous:      %8lu kB\n"
 		   "Swap:           %8lu kB\n"
 		   "KernelPageSize: %8lu kB\n"
 		   "MMUPageSize:    %8lu kB\n",
@@ -420,6 +425,7 @@ static int show_smap(struct seq_file *m, void *v)
 		   mss.private_clean >> 10,
 		   mss.private_dirty >> 10,
 		   mss.referenced >> 10,
+		   mss.anonymous >> 10,
 		   mss.swap >> 10,
 		   vma_kernel_pagesize(vma) >> 10,
 		   vma_mmu_pagesize(vma) >> 10);