Add paranoid checking of hugepage pool sizes

This patch adds code to the run_tests.py script to check the state of
all the hugepage pools before and after each testcase.  When turned on
(with the new '-c' option to run_tests.py), it will report an error if
the pool sizes are different after the test than before.

Obviously this can report bogus errors if other programs are using
hugepages on the system, or if dynamic pools are enabled.  Nonetheless
it can be useful it can be useful for detecting and tracking down
subtle kernel bugs which result in misaccounting of the pool state
(I've used it to debug such problems in a new hugepage port).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Eric B Munson <ebmunson@us.ibm.com>

1 files changed, 26 insertions, 2 deletions

diff --git a/tests/run_tests.py b/tests/run_tests.py
index ac87703..547dd72 100755
--- a/tests/run_tests.py
+++ b/tests/run_tests.py
@@ -48,7 +48,19 @@ def bash(cmd):
     out = p.stdout.read().strip()
     return (rc, out)
 
+def snapshot_pool_state():
+    l = []
+    for d in os.listdir("/sys/kernel/mm/hugepages"):
+        substate = [(f, int(open("/sys/kernel/mm/hugepages/%s/%s" % (d, f)).read()))
+                    for f in os.listdir("/sys/kernel/mm/hugepages/%s" % d)]
+        l.append((d, tuple(substate)))
+    return tuple(l)
+
 def run_test_prog(bits, pagesize, cmd, **env):
+    if paranoid_pool_check:
+        beforepool = snapshot_pool_state()
+        print "Pool state: %s" % str(beforepool)
+
     local_env = os.environ.copy()
     local_env.update(env)
     local_env["PATH"] = "./obj%d:../obj%d:%s" \
@@ -64,6 +76,15 @@ def run_test_prog(bits, pagesize, cmd, **env):
         # Abort and mark this a strange test result
         return (None, "")
     out = p.stdout.read().strip()
+
+    if paranoid_pool_check:
+        afterpool = snapshot_pool_state()
+        if afterpool != beforepool:
+            print >>sys.stderr, "Hugepage pool state not preserved!"
+            print >>sys.stderr, "BEFORE: %s" % str(beforepool)
+            print >>sys.stderr, "AFTER: %s" % str(afterpool)
+            sys.exit(98)
+
     return (rc, out)
 
 def setup_env(override, defaults):
@@ -584,15 +605,16 @@ def stress_tests():
 
 
 def main():
-    global wordsizes, pagesizes, dangerous
+    global wordsizes, pagesizes, dangerous, paranoid_pool_check
     testsets = set()
     env_override = {"QUIET_TEST": "1", "HUGETLBFS_MOUNTS": "",
                     "HUGETLB_ELFMAP": None, "HUGETLB_MORECORE": None}
     env_defaults = {"HUGETLB_VERBOSE": "0"}
     dangerous = 0
+    paranoid_pool_check = False
 
     try:
-        opts, args = getopt.getopt(sys.argv[1:], "vVfdt:b:p:")
+        opts, args = getopt.getopt(sys.argv[1:], "vVfdt:b:p:c")
     except getopt.GetoptError, err:
         print str(err)
         sys.exit(1)
@@ -610,6 +632,8 @@ def main():
            for b in arg.split(): wordsizes.add(int(b))
        elif opt == "-p":
            for p in arg.split(): pagesizes.add(int(p))
+       elif opt == '-c':
+           paranoid_pool_check = True
        else:
            assert False, "unhandled option"
     if len(testsets) == 0: testsets = set(["func", "stress"])