diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 7897a7dafcbc..d49af173b5af 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -461,6 +461,7 @@ Memory Area, or VMA) there is a series of lines such as the following::
     Private_Dirty:         0 kB
     Referenced:          892 kB
     Anonymous:             0 kB
+    KSM:                   0 kB
     LazyFree:              0 kB
     AnonHugePages:         0 kB
     ShmemPmdMapped:        0 kB
@@ -501,6 +502,9 @@ accessed.
 a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
 and a page is modified, the file page is replaced by a private anonymous copy.
 
+"KSM" reports how many of the pages are KSM pages. Note that KSM-placed zeropages
+are not included, only actual KSM pages.
+
 "LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE).
 The memory isn't freed immediately with madvise(). It's freed in memory
 pressure if the memory is clean. Please note that the printed value might
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 15ddf4653a19..5fc732cb2350 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -4,6 +4,7 @@
 #include <linux/hugetlb.h>
 #include <linux/huge_mm.h>
 #include <linux/mount.h>
+#include <linux/ksm.h>
 #include <linux/seq_file.h>
 #include <linux/highmem.h>
 #include <linux/ptrace.h>
@@ -396,6 +397,7 @@ struct mem_size_stats {
 	unsigned long swap;
 	unsigned long shared_hugetlb;
 	unsigned long private_hugetlb;
+	unsigned long ksm;
 	u64 pss;
 	u64 pss_anon;
 	u64 pss_file;
@@ -452,6 +454,9 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page,
 			mss->lazyfree += size;
 	}
 
+	if (PageKsm(page))
+		mss->ksm += size;
+
 	mss->resident += size;
 	/* Accumulate the size in pages that have been accessed. */
 	if (young || page_is_young(page) || PageReferenced(page))
@@ -822,6 +827,7 @@ static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss,
 	SEQ_PUT_DEC(" kB\nPrivate_Dirty:  ", mss->private_dirty);
 	SEQ_PUT_DEC(" kB\nReferenced:     ", mss->referenced);
 	SEQ_PUT_DEC(" kB\nAnonymous:      ", mss->anonymous);
+	SEQ_PUT_DEC(" kB\nKSM:            ", mss->ksm);
 	SEQ_PUT_DEC(" kB\nLazyFree:       ", mss->lazyfree);
 	SEQ_PUT_DEC(" kB\nAnonHugePages:  ", mss->anonymous_thp);
 	SEQ_PUT_DEC(" kB\nShmemPmdMapped: ", mss->shmem_thp);