/proc/pid/smaps: export amount of anonymous memory in a mapping

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.

Exporting this count will help gdb to make a better decision on which
areas need to be dumped in its coredump; and should be useful to others
studying the memory usage of a process.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 871e25ed0069..da6b01d70f01 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -327,6 +327,7 @@ struct mem_size_stats {
         unsigned long private_clean;
         unsigned long private_dirty;
         unsigned long referenced;
+        unsigned long anonymous;
         unsigned long swap;
         u64 pss;
 };
@@ -357,6 +358,9 @@ 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))
@@ -410,6 +414,7 @@ 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",
@@ -421,6 +426,7 @@ 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);