From 87f0b565c1694034286c8357d3ec6947c6aa23cc Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Fri, 14 May 2021 10:39:47 +1000
Subject: [PATCH] BACKPORT: FROMGIT: userfaultfd/selftests: only dump counts if
 mode enabled

WP and MINOR modes are conditionally enabled on specific memory types.
This patch avoids dumping tons of zeros for those cases when the modes are
not supported at all.

Link: https://lkml.kernel.org/r/20210412232753.1012412-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Wang Qing <wangqing@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
(cherry picked from commit 5edabbbe74eee6c1c59dafbbfb5528e391be447c
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
akpm)
Link: https://lore.kernel.org/patchwork/patch/1412453/

Conflicts: tools/testing/selftests/vm/userfaultfd.c
(1. Manual rebase
2. Removed 'wp_total' related change in uffd_stats_report() as
write-protect test doesn't exist.)

Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Bug: 187930641
Change-Id: I445f883f3402104ea39d50ea60726b16394f6e50
---
 tools/testing/selftests/vm/userfaultfd.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index 2f2855d8f595..aee35b1ff76c 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -157,13 +157,20 @@ static void uffd_stats_report(struct uffd_stats *stats, int n_cpus)
 		minor_total += stats[i].minor_faults;
 	}
 
-	printf("userfaults: %llu missing (", miss_total);
-	for (i = 0; i < n_cpus; i++)
-		printf("%lu+", stats[i].missing_faults);
-	printf("\b), %llu minor (", minor_total);
-	for (i = 0; i < n_cpus; i++)
-		printf("%lu+", stats[i].minor_faults);
-	printf("\b)\n");
+	printf("userfaults: ");
+	if (miss_total) {
+		printf("%llu missing (", miss_total);
+		for (i = 0; i < n_cpus; i++)
+			printf("%lu+", stats[i].missing_faults);
+		printf("\b) ");
+	}
+	if (minor_total) {
+		printf("%llu minor (", minor_total);
+		for (i = 0; i < n_cpus; i++)
+			printf("%lu+", stats[i].minor_faults);
+		printf("\b)");
+	}
+	printf("\n");
 }
 
 static int anon_release_pages(char *rel_area)