mm: /proc/pid/smaps: factor out common stats printing

To prepare for handling /proc/pid/smaps_rollup differently from
/proc/pid/smaps factor out from show_smap() printing the parts of output
that are common for both variants, which is the bulk of the gathered
memory stats.

[vbabka@suse.cz: add const, per Alexey]
  Link: http://lkml.kernel.org/r/b45f319f-cd04-337b-37f8-77f99786aa8a@suse.cz
Link: http://lkml.kernel.org/r/20180723111933.15443-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Daniel Colascione <dancol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/task_mmu.c

@@ -747,6 +747,32 @@ static void smap_gather_stats(struct vm_area_struct *vma,
 
 #define SEQ_PUT_DEC(str, val) \
 		seq_put_decimal_ull_width(m, str, (val) >> 10, 8)
+
+/* Show the contents common for smaps and smaps_rollup */
+static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss)
+{
+	SEQ_PUT_DEC("Rss:            ", mss->resident);
+	SEQ_PUT_DEC(" kB\nPss:            ", mss->pss >> PSS_SHIFT);
+	SEQ_PUT_DEC(" kB\nShared_Clean:   ", mss->shared_clean);
+	SEQ_PUT_DEC(" kB\nShared_Dirty:   ", mss->shared_dirty);
+	SEQ_PUT_DEC(" kB\nPrivate_Clean:  ", mss->private_clean);
+	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\nLazyFree:       ", mss->lazyfree);
+	SEQ_PUT_DEC(" kB\nAnonHugePages:  ", mss->anonymous_thp);
+	SEQ_PUT_DEC(" kB\nShmemPmdMapped: ", mss->shmem_thp);
+	SEQ_PUT_DEC(" kB\nShared_Hugetlb: ", mss->shared_hugetlb);
+	seq_put_decimal_ull_width(m, " kB\nPrivate_Hugetlb: ",
+				  mss->private_hugetlb >> 10, 7);
+	SEQ_PUT_DEC(" kB\nSwap:           ", mss->swap);
+	SEQ_PUT_DEC(" kB\nSwapPss:        ",
+					mss->swap_pss >> PSS_SHIFT);
+	SEQ_PUT_DEC(" kB\nLocked:         ",
+					mss->pss_locked >> PSS_SHIFT);
+	seq_puts(m, " kB\n");
+}
+
 static int show_smap(struct seq_file *m, void *v)
 {
 	struct proc_maps_private *priv = m->private;
@@ -791,28 +817,9 @@ static int show_smap(struct seq_file *m, void *v)
 		seq_puts(m, " kB\n");
 	}
 
-	if (!rollup_mode || last_vma) {
-		SEQ_PUT_DEC("Rss:            ", mss->resident);
-		SEQ_PUT_DEC(" kB\nPss:            ", mss->pss >> PSS_SHIFT);
-		SEQ_PUT_DEC(" kB\nShared_Clean:   ", mss->shared_clean);
-		SEQ_PUT_DEC(" kB\nShared_Dirty:   ", mss->shared_dirty);
-		SEQ_PUT_DEC(" kB\nPrivate_Clean:  ", mss->private_clean);
-		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\nLazyFree:       ", mss->lazyfree);
-		SEQ_PUT_DEC(" kB\nAnonHugePages:  ", mss->anonymous_thp);
-		SEQ_PUT_DEC(" kB\nShmemPmdMapped: ", mss->shmem_thp);
-		SEQ_PUT_DEC(" kB\nShared_Hugetlb: ", mss->shared_hugetlb);
-		seq_put_decimal_ull_width(m, " kB\nPrivate_Hugetlb: ",
-					  mss->private_hugetlb >> 10, 7);
-		SEQ_PUT_DEC(" kB\nSwap:           ", mss->swap);
-		SEQ_PUT_DEC(" kB\nSwapPss:        ",
-						mss->swap_pss >> PSS_SHIFT);
-		SEQ_PUT_DEC(" kB\nLocked:         ",
-						mss->pss_locked >> PSS_SHIFT);
-		seq_puts(m, " kB\n");
-	}
+	if (!rollup_mode || last_vma)
+		__show_smap(m, mss);
+
 	if (!rollup_mode) {
 		if (arch_pkeys_enabled())
 			seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));