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cg: Fix restoration of tasks into existing cgroups

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When we omit the --manage-cgroups on dump the controllers section
in cgroups image lacks the none-d entries (the name=systemd is the
most typical).

If it happens, that init task lives in non-criu cgset (it can be
so if we do --shell-job dump from another terminal and see criu
and root task living in different user.slice systemd cgroups) then
on restore the move_in_cgroup() would fail to lookup the required
controller.

In order to fix this we should still call the collect_cgroups()
on dump, so that it adds the none-d controllers into the list,
but don't dump the dirs tree itself.

The patch looks ugly, but it just moves the current_controller
evaluation from the middle of the loop upwards (and renames the
char *opts variable not to conflict with global opts).

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Tycho Andersen <tycho.andersen@canonical.com>
This commit is contained in:
Pavel Emelyanov 2014-08-13 16:24:00 +04:00
parent e301b1d56c
commit bf91821f11
1 changed files with 31 additions and 28 deletions
Download patch file Download diff file Expand all files Collapse all files

59
cgroup.c
View file

@ -490,36 +490,10 @@ static int collect_cgroups(struct list_head *ctls)
int fd = -1;
list_for_each_entry(cc, ctls, l) {
char path[PATH_MAX], opts[1024];
char path[PATH_MAX], mopts[1024];
char *name, prefix[] = ".criu.cgmounts.XXXXXX";
struct cg_controller *cg;
if (strstartswith(cc->name, "name=")) {
name = cc->name + 5;
snprintf(opts, sizeof(opts), "none,%s", cc->name);
} else {
name = cc->name;
snprintf(opts, sizeof(opts), "%s", name);
}
if (mkdtemp(prefix) == NULL) {
pr_perror("can't make dir for cg mounts\n");
return -1;
}
if (mount("none", prefix, "cgroup", 0, opts) < 0) {
pr_perror("couldn't mount %s\n", opts);
rmdir(prefix);
return -1;
}
fd = open_detach_mount(prefix);
if (fd < 0)
return -1;
path_pref_len = snprintf(path, PATH_MAX, "/proc/self/fd/%d", fd);
snprintf(path + path_pref_len, PATH_MAX - path_pref_len, "%s", cc->path);
current_controller = NULL;
/* We should get all the "real" (i.e. not name=systemd type)
@ -546,6 +520,35 @@ static int collect_cgroups(struct list_head *ctls)
}
}
if (!opts.manage_cgroups)
continue;
if (strstartswith(cc->name, "name=")) {
name = cc->name + 5;
snprintf(mopts, sizeof(mopts), "none,%s", cc->name);
} else {
name = cc->name;
snprintf(mopts, sizeof(mopts), "%s", name);
}
if (mkdtemp(prefix) == NULL) {
pr_perror("can't make dir for cg mounts\n");
return -1;
}
if (mount("none", prefix, "cgroup", 0, mopts) < 0) {
pr_perror("couldn't mount %s\n", mopts);
rmdir(prefix);
return -1;
}
fd = open_detach_mount(prefix);
if (fd < 0)
return -1;
path_pref_len = snprintf(path, PATH_MAX, "/proc/self/fd/%d", fd);
snprintf(path + path_pref_len, PATH_MAX - path_pref_len, "%s", cc->path);
ret = ftw(path, add_cgroup, 4);
if (ret < 0) {
pr_perror("failed walking %s for empty cgroups\n", path);
@ -595,7 +598,7 @@ int dump_task_cgroup(struct pstree_item *item, u32 *cg_id)
* The on-stack ctls is moved into cs inside
* the get_cg_set routine.
*/
if (cs != criu_cgset && opts.manage_cgroups && collect_cgroups(&cs->ctls))
if (cs != criu_cgset && collect_cgroups(&cs->ctls))
return -1;
}