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| author | наб <nabijaczleweli@nabijaczleweli.xyz> | 2021-05-07 22:10:16 +0000 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2021-05-07 22:10:16 +0000 |
| commit | 3bd6b0e05acfd9e79b095bacb32789c1821d26a8 (patch) | |
| tree | cb7b7f2d75116a717770fdf7d1cfe2bf688bd6be | |
| parent | c074a7de1366656f77635da9db02cf5c09798cae (diff) | |
| download | src-3bd6b0e05acfd9e79b095bacb32789c1821d26a8.tar.gz src-3bd6b0e05acfd9e79b095bacb32789c1821d26a8.zip | |
zed: protect against wait4()/fork() races to the global PID table
This can be very easily triggered by adding a sleep(1) before
the wait4() on a PID-starved system: the reaper thread would wait
for a child before its entry appeared, letting old entries accumulate:
Invoking "all-debug.sh" eid=3021 pid=391
Finished "(null)" eid=0 pid=391 time=0.002432s exit=0
Invoking "all-syslog.sh" eid=3021 pid=336
Finished "(null)" eid=0 pid=336 time=0.002432s exit=0
Invoking "history_event-zfs-list-cacher.sh" eid=3021 pid=347
Invoking "all-debug.sh" eid=3022 pid=349
Finished "history_event-zfs-list-cacher.sh" eid=3021 pid=347
time=0.001669s exit=0
Finished "(null)" eid=0 pid=349 time=0.002404s exit=0
Invoking "all-syslog.sh" eid=3022 pid=370
Finished "(null)" eid=0 pid=370 time=0.002427s exit=0
Invoking "history_event-zfs-list-cacher.sh" eid=3022 pid=391
avl_find(tree, new_node, &where) == NULL
ASSERT at ../../module/avl/avl.c:641:avl_add()
Thread 1 "zed" received signal SIGABRT, Aborted.
By employing this wider lock, we atomise [wait, remove] and [fork, add]:
slowing down the reaper thread now just causes some zombies
to accumulate until it can get to them
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Don Brady <don.brady@delphix.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #11963
Closes #11965
| -rw-r--r-- | cmd/zed/zed_exec.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/cmd/zed/zed_exec.c b/cmd/zed/zed_exec.c index 9b0775a7469e..0a6782f0205e 100644 --- a/cmd/zed/zed_exec.c +++ b/cmd/zed/zed_exec.c @@ -142,8 +142,10 @@ _zed_exec_fork_child(uint64_t eid, const char *dir, const char *prog, prog, eid, strerror(ENAMETOOLONG)); return; } + (void) pthread_mutex_lock(&_launched_processes_lock); pid = fork(); if (pid < 0) { + (void) pthread_mutex_unlock(&_launched_processes_lock); zed_log_msg(LOG_WARNING, "Failed to fork \"%s\" for eid=%llu: %s", prog, eid, strerror(errno)); @@ -166,20 +168,19 @@ _zed_exec_fork_child(uint64_t eid, const char *dir, const char *prog, /* parent process */ - __atomic_sub_fetch(&_launched_processes_limit, 1, __ATOMIC_SEQ_CST); - zed_log_msg(LOG_INFO, "Invoking \"%s\" eid=%llu pid=%d", - prog, eid, pid); - node = calloc(1, sizeof (*node)); if (node) { node->pid = pid; node->eid = eid; node->name = strdup(prog); - (void) pthread_mutex_lock(&_launched_processes_lock); avl_add(&_launched_processes, node); - (void) pthread_mutex_unlock(&_launched_processes_lock); } + (void) pthread_mutex_unlock(&_launched_processes_lock); + + __atomic_sub_fetch(&_launched_processes_limit, 1, __ATOMIC_SEQ_CST); + zed_log_msg(LOG_INFO, "Invoking \"%s\" eid=%llu pid=%d", + prog, eid, pid); } static void |