[PATCH V3 6/7] proc: show MADV_FREE pages info in smaps

[Shaohua Li <shli@fb.com>]

show MADV_FREE pages info of each vma in smaps. This is mainly for
diagnose purpose. Userspace could use it to understand what happens in
the vma.

Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
---
 fs/proc/task_mmu.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index ee3efb2..8f2423f 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -440,6 +440,7 @@ struct mem_size_stats {
 	unsigned long private_dirty;
 	unsigned long referenced;
 	unsigned long anonymous;
+	unsigned long lazyfree;
 	unsigned long anonymous_thp;
 	unsigned long shmem_thp;
 	unsigned long swap;
@@ -456,8 +457,11 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page,
 	int i, nr = compound ? 1 << compound_order(page) : 1;
 	unsigned long size = nr * PAGE_SIZE;
 
-	if (PageAnon(page))
+	if (PageAnon(page)) {
 		mss->anonymous += size;
+		if (!PageSwapBacked(page))
+			mss->lazyfree += size;
+	}
 
 	mss->resident += size;
 	/* Accumulate the size in pages that have been accessed. */
@@ -770,6 +774,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
 		   "Private_Dirty:  %8lu kB\n"
 		   "Referenced:     %8lu kB\n"
 		   "Anonymous:      %8lu kB\n"
+		   "LazyFree:       %8lu kB\n"
 		   "AnonHugePages:  %8lu kB\n"
 		   "ShmemPmdMapped: %8lu kB\n"
 		   "Shared_Hugetlb: %8lu kB\n"
@@ -788,6 +793,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
 		   mss.private_dirty >> 10,
 		   mss.referenced >> 10,
 		   mss.anonymous >> 10,
+		   mss.lazyfree >> 10,
 		   mss.anonymous_thp >> 10,
 		   mss.shmem_thp >> 10,
 		   mss.shared_hugetlb >> 10,
-- 
2.9.3