Add Linux kmemleak support to ZTS

- Kmemleak `clear` is invoked right before every test case run.
- Kmemleak `scan` is requested right after each test case is finished.
- Kmemleak instrumentation is not used for
  setup/cleanup/pretest/posttest/failsafe stages to shorten the test
  case execution time.
- Kmemleak periodic scan is disabled (`scan=0`) before the test suite
  run to avoid interfering with the on-demand scan results.
- There are unavoidable potential false positives coming from kernel
  areas other than OpenZFS module.
- The ZTS with kmemleak enabled duration is increased by ~50%.

Example run
```
Running Time:   07:12:13
Percent passed: 98.3%

unreferenced object 0xffff9da82aea5410 (size 80):
  comm "kworker/u32:10", pid 942206, jiffies 4296749716 (age 2615.516s)
  hex dump (first 32 bytes):
    00 30 30 00 00 00 00 00 ff 8f 30 00 00 00 00 00  .00.......0.....
    51 e6 77 05 a8 9d ff ff 00 00 00 00 00 00 00 00  Q.w.............
  backtrace:
    [<000000005cf1fea2>] alloc_extent_state+0x1d/0xb0 [btrfs]
    [<0000000083f78ae5>] set_extent_bit+0x2ff/0x670 [btrfs]
    [<00000000de29249e>] lock_extent_bits+0x6b/0xa0 [btrfs]
    [<00000000b241f424>] lock_and_cleanup_extent_if_need+0xaf/0x1c0
       [btrfs]
    [<0000000093ca72b5>] btrfs_buffered_write+0x297/0x7d0 [btrfs]
    [<000000002c2938c8>] btrfs_file_write_iter+0x127/0x390 [btrfs]
    [<00000000b888f720>] do_iter_readv_writev+0x152/0x1b0
    [<00000000320f0bcc>] do_iter_write+0x7c/0x1c0
    [<000000000b5a8fe0>] lo_write_bvec+0x62/0x150 [loop]
    [<000000009aa03c73>] loop_process_work+0x250/0xbd0 [loop]
    [<00000000c7487d8a>] process_one_work+0x1f1/0x390
    [<000000000b236831>] worker_thread+0x53/0x3e0
    [<0000000023cb3e57>] kthread+0x127/0x150
    [<000000002d48676a>] ret_from_fork+0x22/0x30
```

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: szubersk <szuberskidamian@gmail.com>
Closes #13084

scripts/zfs-tests.sh

@@ -53,6 +53,7 @@ ZFS_DBGMSG="$STF_SUITE/callbacks/zfs_dbgmsg.ksh"
 ZFS_DMESG="$STF_SUITE/callbacks/zfs_dmesg.ksh"
 UNAME=$(uname -s)
 RERUN=""
+KMEMLEAK=""
 
 # Override some defaults if on FreeBSD
 if [ "$UNAME" = "FreeBSD" ] ; then
@@ -328,6 +329,7 @@ OPTIONS:
 	-S          Enable stack tracer (negative performance impact)
 	-c          Only create and populate constrained path
 	-R          Automatically rerun failing tests
+	-m          Enable kmemleak reporting (Linux only)
 	-n NFSFILE  Use the nfsfile to determine the NFS configuration
 	-I NUM      Number of iterations
 	-d DIR      Use DIR for files and loopback devices
@@ -354,7 +356,7 @@ $0 -x
 EOF
 }
 
-while getopts 'hvqxkfScRn:d:s:r:?t:T:u:I:' OPTION; do
+while getopts 'hvqxkfScRmn:d:s:r:?t:T:u:I:' OPTION; do
 	case $OPTION in
 	h)
 		usage
@@ -385,6 +387,9 @@ while getopts 'hvqxkfScRn:d:s:r:?t:T:u:I:' OPTION; do
 	R)
 		RERUN="yes"
 		;;
+	m)
+		KMEMLEAK="yes"
+		;;
 	n)
 		nfsfile=$OPTARG
 		[ -f "$nfsfile" ] || fail "Cannot read file: $nfsfile"
@@ -694,12 +699,14 @@ REPORT_FILE=$(mktemp_file zts-report)
 #
 # Run all the tests as specified.
 #
-msg "${TEST_RUNNER} ${QUIET:+-q}" \
+msg "${TEST_RUNNER}" \
+    "${QUIET:+-q}" \
+    "${KMEMLEAK:+-m}" \
     "-c \"${RUNFILES}\"" \
     "-T \"${TAGS}\"" \
     "-i \"${STF_SUITE}\"" \
     "-I \"${ITERATIONS}\""
-${TEST_RUNNER} ${QUIET:+-q} \
+${TEST_RUNNER} ${QUIET:+-q} ${KMEMLEAK:+-m} \
     -c "${RUNFILES}" \
     -T "${TAGS}" \
     -i "${STF_SUITE}" \
@@ -719,7 +726,7 @@ if [ "$RESULT" -eq "2" ] && [ -n "$RERUN" ]; then
 	for test_name in $MAYBES; do
 		grep "$test_name " "$TEMP_RESULTS_FILE" >>"$TEST_LIST"
 	done
-	${TEST_RUNNER} ${QUIET:+-q} \
+	${TEST_RUNNER} ${QUIET:+-q} ${KMEMLEAK:+-m} \
 	    -c "${RUNFILES}" \
 	    -T "${TAGS}" \
 	    -i "${STF_SUITE}" \

tests/test-runner/bin/test-runner.py.in

@@ -36,11 +36,13 @@ from pwd import getpwuid
 from select import select
 from subprocess import PIPE
 from subprocess import Popen
+from subprocess import check_output
 from threading import Timer
 from time import time
 
 BASEDIR = '/var/tmp/test_results'
 TESTDIR = '/usr/share/zfs/'
+KMEMLEAK_FILE = '/sys/kernel/debug/kmemleak'
 KILL = 'kill'
 TRUE = 'true'
 SUDO = 'sudo'
@@ -83,6 +85,7 @@ class Result(object):
         self.runtime = ''
         self.stdout = []
         self.stderr = []
+        self.kmemleak = ''
         self.result = ''
 
     def done(self, proc, killed, reran):
@@ -98,6 +101,9 @@ class Result(object):
         if killed:
             self.result = 'KILLED'
             Result.runresults['KILLED'] += 1
+        elif len(self.kmemleak) > 0:
+            self.result = 'FAIL'
+            Result.runresults['FAIL'] += 1
         elif self.returncode == 0:
             self.result = 'PASS'
             Result.runresults['PASS'] += 1
@@ -258,7 +264,7 @@ User: %s
 
         return out.lines, err.lines
 
-    def run(self, dryrun):
+    def run(self, dryrun, kmemleak):
         """
         This is the main function that runs each individual test.
         Determine whether or not the command requires sudo, and modify it
@@ -278,6 +284,11 @@ User: %s
             fail('%s' % e)
 
         self.result.starttime = monotonic_time()
+
+        if kmemleak:
+            cmd = f'echo clear | {SUDO} tee {KMEMLEAK_FILE}'
+            check_output(cmd, shell=True)
+
         proc = Popen(privcmd, stdout=PIPE, stderr=PIPE)
         # Allow a special timeout value of 0 to mean infinity
         if int(self.timeout) == 0:
@@ -287,6 +298,12 @@ User: %s
         try:
             t.start()
             self.result.stdout, self.result.stderr = self.collect_output(proc)
+
+            if kmemleak:
+                cmd = f'echo scan | {SUDO} tee {KMEMLEAK_FILE}'
+                check_output(cmd, shell=True)
+                cmd = f'{SUDO} cat {KMEMLEAK_FILE}'
+                self.result.kmemleak = check_output(cmd, shell=True)
         except KeyboardInterrupt:
             self.kill_cmd(proc, True)
             fail('\nRun terminated at user request.')
@@ -363,6 +380,9 @@ User: %s
             with open(os.path.join(self.outputdir, 'merged'), 'wb') as merged:
                 for _, line in lines:
                     os.write(merged.fileno(), b'%s\n' % line)
+        if len(self.result.kmemleak):
+            with open(os.path.join(self.outputdir, 'kmemleak'), 'wb') as kmem:
+                kmem.write(self.result.kmemleak)
 
 
 class Test(Cmd):
@@ -447,14 +467,14 @@ Tags: %s
 
         cont = True
         if len(pretest.pathname):
-            pretest.run(options.dryrun)
+            pretest.run(options.dryrun, False)
             cont = pretest.result.result == 'PASS'
             pretest.log(options)
 
         if cont:
-            test.run(options.dryrun)
+            test.run(options.dryrun, options.kmemleak)
             if test.result.result == 'KILLED' and len(failsafe.pathname):
-                failsafe.run(options.dryrun)
+                failsafe.run(options.dryrun, False)
                 failsafe.log(options, suppress_console=True)
         else:
             test.skip()
@@ -462,7 +482,7 @@ Tags: %s
         test.log(options)
 
         if len(posttest.pathname):
-            posttest.run(options.dryrun)
+            posttest.run(options.dryrun, False)
             posttest.log(options)
 
 
@@ -565,7 +585,7 @@ Tags: %s
 
         cont = True
         if len(pretest.pathname):
-            pretest.run(options.dryrun)
+            pretest.run(options.dryrun, False)
             cont = pretest.result.result == 'PASS'
             pretest.log(options)
 
@@ -578,9 +598,9 @@ Tags: %s
             failsafe = Cmd(self.failsafe, outputdir=odir, timeout=self.timeout,
                            user=self.failsafe_user, identifier=self.identifier)
             if cont:
-                test.run(options.dryrun)
+                test.run(options.dryrun, options.kmemleak)
                 if test.result.result == 'KILLED' and len(failsafe.pathname):
-                    failsafe.run(options.dryrun)
+                    failsafe.run(options.dryrun, False)
                     failsafe.log(options, suppress_console=True)
             else:
                 test.skip()
@@ -588,7 +608,7 @@ Tags: %s
             test.log(options)
 
         if len(posttest.pathname):
-            posttest.run(options.dryrun)
+            posttest.run(options.dryrun, False)
             posttest.log(options)
 
 
@@ -853,6 +873,11 @@ class TestRun(object):
         else:
             write_log('Could not make a symlink to directory %s\n' %
                       self.outputdir, LOG_ERR)
+
+        if options.kmemleak:
+            cmd = f'echo scan=0 | {SUDO} tee {KMEMLEAK_FILE}'
+            check_output(cmd, shell=True)
+
         iteration = 0
         while iteration < options.iterations:
             for test in sorted(self.tests.keys()):
@@ -998,6 +1023,14 @@ def fail(retstr, ret=1):
     exit(ret)
 
 
+def kmemleak_cb(option, opt_str, value, parser):
+    if not os.path.exists(KMEMLEAK_FILE):
+        fail(f"File '{KMEMLEAK_FILE}' doesn't exist. " +
+             "Enable CONFIG_DEBUG_KMEMLEAK in kernel configuration.")
+
+    setattr(parser.values, option.dest, True)
+
+
 def options_cb(option, opt_str, value, parser):
     path_options = ['outputdir', 'template', 'testdir', 'logfile']
 
@@ -1035,6 +1068,9 @@ def parse_args():
     parser.add_option('-i', action='callback', callback=options_cb,
                       default=TESTDIR, dest='testdir', type='string',
                       metavar='testdir', help='Specify a test directory.')
+    parser.add_option('-m', action='callback', callback=kmemleak_cb,
+                      default=False, dest='kmemleak',
+                      help='Enable kmemleak reporting (Linux only)')
     parser.add_option('-p', action='callback', callback=options_cb,
                       default='', dest='pre', metavar='script',
                       type='string', help='Specify a pre script.')

tests/test-runner/man/test-runner.1

@@ -210,6 +210,8 @@ to be consumed by the run command.
 .It Fl d
 Dry run mode.
 Execute no tests, but print a description of each test that would have been run.
+.It Fl m
+Enable kmemleak reporting (Linux only)
 .It Fl g
 Create test groups from any directories found while searching for tests.
 .It Fl o Ar outputdir