From: mwilck@suse.com
To: Christophe Varoqui <christophe.varoqui@opensvc.com>,
Benjamin Marzinski <bmarzins@redhat.com>
Cc: lixiaokeng@huawei.com, dm-devel@redhat.com,
Martin Wilck <mwilck@suse.com>
Subject: [PATCH 02/23] multipathd: Fix liburcu memory leak
Date: Thu, 24 Sep 2020 15:40:33 +0200 [thread overview]
Message-ID: <20200924134054.14632-3-mwilck@suse.com> (raw)
In-Reply-To: <20200924134054.14632-1-mwilck@suse.com>
From: Martin Wilck <mwilck@suse.com>
Fix this leak in multipathd, reported by valgrind, that messes up
multipathd's otherwise clean leak report:
==23823== 336 bytes in 1 blocks are possibly lost in loss record 3 of 3
==23823== at 0x483AB65: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==23823== by 0x4012F16: _dl_allocate_tls (in /lib64/ld-2.31.so)
==23823== by 0x493BB8E: pthread_create@@GLIBC_2.2.5 (in /lib64/libpthread-2.31.so)
==23823== by 0x492A9A9: call_rcu_data_init (urcu-call-rcu-impl.h:437)
==23823== by 0x492AD2F: UnknownInlinedFun (urcu-call-rcu-impl.h:492)
==23823== by 0x492AD2F: create_call_rcu_data_memb (urcu-call-rcu-impl.h:504)
==23823== by 0x1164E3: child.constprop.0.isra.0 (main.c:2915)
==23823== by 0x10F50C: main (main.c:3335)
==23823==
==23823== LEAK SUMMARY:
==23823== definitely lost: 0 bytes in 0 blocks
==23823== indirectly lost: 0 bytes in 0 blocks
==23823== possibly lost: 336 bytes in 1 blocks
The problem is caused by using liburcu's default RCU call handler,
which liburcu refuses to stop/join. See comments in the code.
Signed-off-by: Martin Wilck <mwilck@suse.com>
---
multipathd/main.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)
diff --git a/multipathd/main.c b/multipathd/main.c
index c5c374b..be1b5ae 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -2889,6 +2889,47 @@ set_oom_adj (void)
condlog(0, "couldn't adjust oom score");
}
+/*
+ * Use a non-default call_rcu_data for child().
+ *
+ * We do this to avoid a memory leak from liburcu.
+ * liburcu never frees the default rcu handler (see comments on
+ * call_rcu_data_free() in urcu-call-rcu-impl.h), its thread
+ * can't be joined with pthread_join(), leaving a memory leak.
+ *
+ * Therefore we create our own, which can be destroyed and joined.
+ */
+static struct call_rcu_data *setup_rcu(void)
+{
+ struct call_rcu_data *crdp;
+
+ rcu_init();
+ rcu_register_thread();
+ crdp = create_call_rcu_data(0UL, -1);
+ if (crdp != NULL)
+ set_thread_call_rcu_data(crdp);
+ return crdp;
+}
+
+static void cleanup_rcu(int dummy __attribute__((unused)), void *arg)
+{
+ struct call_rcu_data *crdp = arg;
+ pthread_t rcu_thread;
+
+ /* Wait for any pending RCU calls */
+ rcu_barrier();
+ if (crdp != NULL) {
+ rcu_thread = get_call_rcu_thread(crdp);
+ /* detach this thread from the RCU thread */
+ set_thread_call_rcu_data(NULL);
+ synchronize_rcu();
+ /* tell RCU thread to exit */
+ call_rcu_data_free(crdp);
+ pthread_join(rcu_thread, NULL);
+ }
+ rcu_unregister_thread();
+}
+
static int
child (__attribute__((unused)) void *param)
{
@@ -2903,10 +2944,12 @@ child (__attribute__((unused)) void *param)
char *envp;
int queue_without_daemon;
enum daemon_status state;
+ struct call_rcu_data *crdp;
mlockall(MCL_CURRENT | MCL_FUTURE);
signal_init();
- rcu_init();
+ crdp = setup_rcu();
+ on_exit(cleanup_rcu, crdp);
setup_thread_attr(&misc_attr, 64 * 1024, 0);
setup_thread_attr(&uevent_attr, DEFAULT_UEVENT_STACKSIZE * 1024, 0);
--
2.28.0
next prev parent reply other threads:[~2020-09-24 13:40 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 13:40 [PATCH 00/23] libmultipath: improve cleanup on exit mwilck
2020-09-24 13:40 ` [PATCH 01/23] multipathd: uxlsnr: avoid deadlock " mwilck
2020-09-26 1:52 ` Benjamin Marzinski
2020-09-26 13:00 ` Martin Wilck
2020-09-24 13:40 ` mwilck [this message]
2020-09-24 13:40 ` [PATCH 03/23] multipathd: move handling of io_err_stat_attr into libmultipath mwilck
2020-09-24 13:40 ` [PATCH 04/23] multipathd: move vecs desctruction into cleanup function mwilck
2020-09-24 13:40 ` [PATCH 05/23] multipathd: make some globals static mwilck
2020-09-24 13:40 ` [PATCH 06/23] multipathd: move threads destruction into separate function mwilck
2020-09-24 13:40 ` [PATCH 07/23] multipathd: move conf " mwilck
2020-09-28 18:03 ` Benjamin Marzinski
2020-09-29 9:12 ` Martin Wilck
2020-09-24 13:40 ` [PATCH 08/23] multipathd: move pid " mwilck
2020-09-24 13:40 ` [PATCH 09/23] multipathd: close pidfile on exit mwilck
2020-09-24 13:40 ` [PATCH 10/23] multipathd: add helper for systemd notification at exit mwilck
2020-09-24 13:40 ` [PATCH 11/23] multipathd: child(): call cleanups in failure case, too mwilck
2020-09-24 13:40 ` [PATCH 12/23] multipathd: unwatch_all_dmevents: check if waiter is initialized mwilck
2020-09-24 13:40 ` [PATCH 13/23] multipathd: print error message if config can't be loaded mwilck
2020-09-24 13:40 ` [PATCH 14/23] libmultipath: add libmp_dm_exit() mwilck
2020-09-28 18:41 ` Benjamin Marzinski
2020-09-24 13:40 ` [PATCH 15/23] multipathd: fixup libdm deinitialization mwilck
2020-09-24 13:40 ` [PATCH 16/23] libmultipath: log_thread_stop(): check if logarea is initialized mwilck
2020-09-24 13:40 ` [PATCH 17/23] multipathd: add cleanup_child() exit handler mwilck
2020-09-24 13:40 ` [PATCH 18/23] libmultipath: fix log_thread startup and teardown mwilck
2020-09-28 20:15 ` Benjamin Marzinski
2020-09-29 9:18 ` Martin Wilck
2020-09-24 13:40 ` [PATCH 19/23] multipathd: move cleanup_{prio, checkers, foreign} to libmultipath_exit mwilck
2020-09-28 20:26 ` Benjamin Marzinski
2020-09-29 9:31 ` Martin Wilck
2020-09-29 17:50 ` Benjamin Marzinski
2020-09-24 13:40 ` [PATCH 20/23] multipath: use atexit() for cleanup handlers mwilck
2020-09-24 13:40 ` [PATCH 21/23] mpathpersist: " mwilck
2020-09-24 13:40 ` [PATCH 22/23] multipath: fix leaks in check_path_valid() mwilck
2020-09-24 13:40 ` [PATCH 23/23] multipath-tools: mpath-tools.supp: file with valgrind suppressions mwilck
2020-09-24 20:58 ` Benjamin Marzinski
2020-09-25 9:53 ` Martin Wilck
2020-09-28 20:51 ` [PATCH 00/23] libmultipath: improve cleanup on exit Benjamin Marzinski
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