found 803013 241-7~deb10u1
thanks
Now updating my machines to buster, I see this issue is still present,
now in systemd version 241-7~deb10u1. The same steps can reproduce:
- Set up cgroups e.g. adding TaskIDs to /sys/fs/cgroup/cpu/DIR/tasks
files. (I use cgrulesengd from package cgroup-tools, but any other
use of cgroups is equally affected.)
- Then when you use systemd commands:
systemctl daemon-reload
systemctl start anacron
you will see your cgroups (your tasks files) becoming empty.
Command daemon-reload seems to happen within "apt-get dist-upgrade"
sequences, and "start anacron" happens nightly. (Some other systemd
commands may also affect.)
and the "same" fix applies: new patch file below, for changed sources.
(Funny how this bug is not getting fixed, in four years...)
Thanks, Paul
--
Paul Szabo p...@maths.usyd.edu.au http://www.maths.usyd.edu.au/u/psz/
School of Mathematics and Statistics University of Sydney Australia
I support NTEU members taking a stand for workplace rights in the face of
poorly-run change management. Visit www.nteu.org.au/sydney to learn more.
diff -r -U18 a-241/src/basic/cgroup-util.c b-241/src/basic/cgroup-util.c
--- a-241/src/basic/cgroup-util.c 2019-02-14 21:11:58.000000000 +1100
+++ b-241/src/basic/cgroup-util.c 2019-09-12 08:53:43.900643247 +1000
@@ -368,36 +368,52 @@
int cg_migrate(
const char *cfrom,
const char *pfrom,
const char *cto,
const char *pto,
CGroupFlags flags) {
bool done = false;
_cleanup_set_free_ Set *s = NULL;
int r, ret = 0;
pid_t my_pid;
assert(cfrom);
assert(pfrom);
assert(cto);
assert(pto);
+ /*
+ * PSz 25 Oct 2015
+ * An empty "to" path is surely wrong
+ * (do not annoy cgroups that are not ours).
+ * PSz 23 Jul 2017
+ * Cannot(?) happen anymore, see:
+ * cg_migrate_recursive_fallback()
+ * cg_migrate_everywhere()
+ * below... log if it does!
+ */
+ if (!strlen(pto)) {
+ log_warning("PSz debug: cg_migrate skip from (%s)%s to (%s)%s", cfrom, pfrom, cto, pto);
+ return ret;
+ }
+ /* log_warning("PSz debug: cg_migrate do from (%s)%s to (%s)%s", cfrom, pfrom, cto, pto); */
+
s = set_new(NULL);
if (!s)
return -ENOMEM;
my_pid = getpid_cached();
do {
_cleanup_fclose_ FILE *f = NULL;
pid_t pid = 0;
done = true;
r = cg_enumerate_processes(cfrom, pfrom, &f);
if (r < 0) {
if (ret >= 0 && r != -ENOENT)
return r;
return ret;
}
@@ -509,36 +525,52 @@
CGroupFlags flags) {
int r;
assert(cfrom);
assert(pfrom);
assert(cto);
assert(pto);
r = cg_migrate_recursive(cfrom, pfrom, cto, pto, flags);
if (r < 0) {
char prefix[strlen(pto) + 1];
/* This didn't work? Then let's try all prefixes of the destination */
PATH_FOREACH_PREFIX(prefix, pto) {
int q;
+ /*
+ * PSz 23 Jul 2017
+ * Skip an empty ("") prefix path: surely wrong,
+ * do not annoy cgroups that are not ours.
+ * Other comments:
+ * - Why this "did not work so try something else"?
+ * - Maybe should have used PATH_FOREACH_PREFIX_MORE
+ * for cleaner, more compact code.
+ * - Should check cg_attach_fallback() also, and maybe
+ * review all other uses of PATH_FOREACH_PREFIX.
+ */
+ if (!strlen(prefix)) {
+ /* log_warning("PSz debug: cg_migrate_recursive_fallback skip from (%s)%s to (%s)[EMPTY prefix of %s]", cfrom, pfrom, cto, pto); */
+ continue;
+ }
+
q = cg_migrate_recursive(cfrom, pfrom, cto, prefix, flags);
if (q >= 0)
return q;
}
}
return r;
}
static const char *controller_to_dirname(const char *controller) {
const char *e;
assert(controller);
/* Converts a controller name to the directory name below
* /sys/fs/cgroup/ we want to mount it to. Effectively, this
* just cuts off the name= prefixed used for named
* hierarchies, if it is specified. */
@@ -2233,38 +2265,46 @@
if (q > 0)
return r;
supported &= CGROUP_MASK_V1;
done = 0;
for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {
CGroupMask bit = CGROUP_CONTROLLER_TO_MASK(c);
const char *p = NULL;
if (!FLAGS_SET(supported, bit))
continue;
if (FLAGS_SET(done, bit))
continue;
if (to_callback)
p = to_callback(bit, userdata);
- if (!p)
+ if (!p) {
p = to;
+ } else if (!strlen(p)) {
+ /*
+ * PSz 12 Sep 2019
+ * Skip an empty path returned by to_callback
+ */
+ /* log_warning("PSz debug: to_callback in cg_migrate_everywhere returned empty, skipping (%s)%s to (%s)%s", SYSTEMD_CGROUP_CONTROLLER, to, cgroup_controller_to_string(c), p); */
+ continue;
+ }
(void) cg_migrate_recursive_fallback(SYSTEMD_CGROUP_CONTROLLER, to, cgroup_controller_to_string(c), p, 0);
done |= CGROUP_MASK_EXTEND_JOINED(bit);
}
return r;
}
int cg_trim_everywhere(CGroupMask supported, const char *path, bool delete_root) {
CGroupController c;
CGroupMask done;
int r, q;
r = cg_trim(SYSTEMD_CGROUP_CONTROLLER, path, delete_root);
if (r < 0)
return r;
q = cg_all_unified();
