From 7c52627446e32df64ad4cd3ac56ad515d0233cea Mon Sep 17 00:00:00 2001 From: Michal Sekletar Date: Fri, 14 Dec 2018 15:17:27 +0100 Subject: [PATCH] journald: correctly attribute log messages also with cgroupsv1 With cgroupsv1 a zombie process is migrated to root cgroup in all hierarchies. This was changed for unified hierarchy and /proc/PID/cgroup reports cgroup to which process belonged before it exited. Be more suspicious about cgroup path reported by the kernel and use unit_id provided by the log client if the kernel reports that process is running in the root cgroup. Users tend to care the most about 'log->unit_id' mapping so systemctl status can correctly report last log lines. Also we wouldn't be able to infer anything useful from "/" path anyway. See: https://github.com/torvalds/linux/commit/2e91fa7f6d451e3ea9fec999065d2fd199691f9d (cherry picked from commit 672773b63a4ebf95242b27e63071b93073ebc1f5) Resolves: #1658115 --- src/journal/journald-context.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/src/journal/journald-context.c b/src/journal/journald-context.c index 51f79fd80..dba3525ed 100644 --- a/src/journal/journald-context.c +++ b/src/journal/journald-context.c @@ -13,6 +13,8 @@ #include "io-util.h" #include "journal-util.h" #include "journald-context.h" +#include "parse-util.h" +#include "path-util.h" #include "process-util.h" #include "procfs-util.h" #include "string-util.h" @@ -281,9 +283,11 @@ static int client_context_read_cgroup(Server *s, ClientContext *c, const char *u /* Try to acquire the current cgroup path */ r = cg_pid_get_path_shifted(c->pid, s->cgroup_root, &t); - if (r < 0) { + if (r < 0 || empty_or_root(t)) { - /* If that didn't work, we use the unit ID passed in as fallback, if we have nothing cached yet */ + /* We use the unit ID passed in as fallback if we have nothing cached yet and cg_pid_get_path_shifted() + * failed or process is running in a root cgroup. Zombie processes are automatically migrated to root cgroup + * on cgroupsv1 and we want to be able to map log messages from them too. */ if (unit_id && !c->unit) { c->unit = strdup(unit_id); if (c->unit)