selftests/damon: test debugfs file reads/writes with huge count

DAMON debugfs interface users were able to trigger warning by writing
some files with arbitrarily large 'count' parameter.  The issue is fixed
with commit db7a347b26fe ("mm/damon/dbgfs: use '__GFP_NOWARN' for
user-specified size buffer allocation").  This commit adds a test case
for the issue in DAMON selftests to avoid future regressions.

Link: https://lkml.kernel.org/r/20211201150440.1088-11-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/tools/testing/selftests/damon/.gitignore b/tools/testing/selftests/damon/.gitignore
new file mode 100644 (file)
index 0000000..c6c2965
--- /dev/null
+++ b/tools/testing/selftests/damon/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+huge_count_read_write

diff --git a/tools/testing/selftests/damon/Makefile b/tools/testing/selftests/damon/Makefile
index 8a3f2cd..f0aa954 100644 (file)
--- a/tools/testing/selftests/damon/Makefile
+++ b/tools/testing/selftests/damon/Makefile
@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 # Makefile for damon selftests
 
+TEST_GEN_FILES += huge_count_read_write
+
 TEST_FILES = _chk_dependency.sh
 TEST_PROGS = debugfs_attrs.sh
 

diff --git a/tools/testing/selftests/damon/debugfs_attrs.sh b/tools/testing/selftests/damon/debugfs_attrs.sh
index 1ef1186..23a7b48 100644 (file)
--- a/tools/testing/selftests/damon/debugfs_attrs.sh
+++ b/tools/testing/selftests/damon/debugfs_attrs.sh
@@ -105,4 +105,22 @@ orig_monitor_on=$(cat "$DBGFS/monitor_on")
 test_write_fail "$DBGFS/monitor_on" "on" "orig_monitor_on" "empty target ids"
 echo "$orig_target_ids" > "$DBGFS/target_ids"
 
+# Test huge count read write
+# ==========================
+
+dmesg -C
+
+for file in "$DBGFS/"*
+do
+       ./huge_count_read_write "$file"
+done
+
+if dmesg | grep -q WARNING
+then
+       dmesg
+       exit 1
+else
+       exit 0
+fi
+
 echo "PASS"

diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
new file mode 100644 (file)
index 0000000..ad7a6b4
--- /dev/null
+++ b/tools/testing/selftests/damon/huge_count_read_write.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: SeongJae Park <sj@kernel.org>
+ */
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+
+void write_read_with_huge_count(char *file)
+{
+       int filedesc = open(file, O_RDWR);
+       char buf[25];
+       int ret;
+
+       printf("%s %s\n", __func__, file);
+       if (filedesc < 0) {
+               fprintf(stderr, "failed opening %s\n", file);
+               exit(1);
+       }
+
+       write(filedesc, "", 0xfffffffful);
+       perror("after write: ");
+       ret = read(filedesc, buf, 0xfffffffful);
+       perror("after read: ");
+       close(filedesc);
+}
+
+int main(int argc, char *argv[])
+{
+       if (argc != 2) {
+               fprintf(stderr, "Usage: %s <file>\n", argv[0]);
+               exit(1);
+       }
+       write_read_with_huge_count(argv[1]);
+
+       return 0;
+}