The commit 1f1562fcd04a ("cgroup/cpuset: Don't let child cpusets restrict parent in default hierarchy") inteded to relax the check only on the default hierarchy (or v2 mode) but it dropped the check in v1 too. This patch returns and separates the legacy-only validations so that they can be considered only in the v1 mode, which should enforce the old constraints for the sake of compatibility.
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| @@ -590,6 +590,35 @@ static inline void free_cpuset(struct cpuset *cs) · 589 unmodified lines | ||
| 590 | 590 | kfree(cs); |
| 591 | 591 | } |
| 592 | 592 | |
| 593 | +/* | |
| 594 | + * validate_change_legacy() - Validate conditions specific to legacy (v1) | |
| 595 | + * behavior. | |
| 596 | + */ | |
| 597 | +static int validate_change_legacy(struct cpuset *cur, struct cpuset *trial) | |
| 598 | +{ | |
| 599 | + struct cgroup_subsys_state *css; | |
| 600 | + struct cpuset *c, *par; | |
| 601 | + int ret; | |
| 602 | + | |
| 603 | + WARN_ON_ONCE(!rcu_read_lock_held()); | |
| 604 | + | |
| 605 | + /* Each of our child cpusets must be a subset of us */ | |
| 606 | + ret = -EBUSY; | |
| 607 | + cpuset_for_each_child(c, css, cur) | |
| 608 | + if (!is_cpuset_subset(c, trial)) | |
| 609 | + goto out; | |
| 610 | + | |
| 611 | + /* On legacy hierarchy, we must be a subset of our parent cpuset. */ | |
| 612 | + ret = -EACCES; | |
| 613 | + par = parent_cs(cur); | |
| 614 | + if (par && !is_cpuset_subset(trial, par)) | |
| 615 | + goto out; | |
| 616 | + | |
| 617 | + ret = 0; | |
| 618 | +out: | |
| 619 | + return ret; | |
| 620 | +} | |
| 621 | + | |
| 593 | 622 | /* |
| 594 | 623 | * validate_change() - Used to validate that any proposed cpuset change |
| 595 | 624 | * follows the structural rules for cpusets. |
| @@ -614,20 +643,21 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial) · 18 unmodified lines | ||
| 614 | 643 | { |
| 615 | 644 | struct cgroup_subsys_state *css; |
| 616 | 645 | struct cpuset *c, *par; |
| 617 | − int ret; | |
| 618 | − | |
| 619 | − /* The checks don't apply to root cpuset */ | |
| 620 | − if (cur == &top_cpuset) | |
| 621 | − return 0; | |
| 646 | + int ret = 0; | |
| 622 | 647 | |
| 623 | 648 | rcu_read_lock(); |
| 624 | − par = parent_cs(cur); | |
| 625 | 649 | |
| 626 | − /* On legacy hierarchy, we must be a subset of our parent cpuset. */ | |
| 627 | − ret = -EACCES; | |
| 628 | − if (!is_in_v2_mode() && !is_cpuset_subset(trial, par)) | |
| 650 | + if (!is_in_v2_mode()) | |
| 651 | + ret = validate_change_legacy(cur, trial); | |
| 652 | + if (ret) | |
| 653 | + goto out; | |
| 654 | + | |
| 655 | + /* Remaining checks don't apply to root cpuset */ | |
| 656 | + if (cur == &top_cpuset) | |
| 629 | 657 | goto out; |
| 630 | 658 | |
| 659 | + par = parent_cs(cur); | |
| 660 | + | |
| 631 | 661 | /* |
| 632 | 662 | * If either I or some sibling (!= me) is exclusive, we can't |
| 633 | 663 | * overlap |
| @@ -1175,9 +1205,7 @@ enum subparts_cmd { · 541 unmodified lines | ||
| 1175 | 1205 | * |
| 1176 | 1206 | * Because of the implicit cpu exclusive nature of a partition root, |
| 1177 | 1207 | * cpumask changes that violates the cpu exclusivity rule will not be |
| 1178 | − * permitted when checked by validate_change(). The validate_change() | |
| 1179 | − * function will also prevent any changes to the cpu list if it is not | |
| 1180 | − * a superset of children's cpu lists. | |
| 1208 | + * permitted when checked by validate_change(). | |
| 1181 | 1209 | */ |
| 1182 | 1210 | static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, |
| 1183 | 1211 | struct cpumask *newmask, |