diff options
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 51 |
1 files changed, 47 insertions, 4 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 0e3a8c11fb3b..07032c088608 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6264,13 +6264,27 @@ struct cgroup_subsys memory_cgrp_subsys = { * budget is NOT proportional. A cgroup's protection from a sibling * is capped to its own memory.min/low setting. * + * 5. However, to allow protecting recursive subtrees from each other + * without having to declare each individual cgroup's fixed share + * of the ancestor's claim to protection, any unutilized - + * "floating" - protection from up the tree is distributed in + * proportion to each cgroup's *usage*. This makes the protection + * neutral wrt sibling cgroups and lets them compete freely over + * the shared parental protection budget, but it protects the + * subtree as a whole from neighboring subtrees. + * + * Note that 4. and 5. are not in conflict: 4. is about protecting + * against immediate siblings whereas 5. is about protecting against + * neighboring subtrees. */ static unsigned long effective_protection(unsigned long usage, + unsigned long parent_usage, unsigned long setting, unsigned long parent_effective, unsigned long siblings_protected) { unsigned long protected; + unsigned long ep; protected = min(usage, setting); /* @@ -6301,7 +6315,34 @@ static unsigned long effective_protection(unsigned long usage, * protection is always dependent on how memory is actually * consumed among the siblings anyway. */ - return protected; + ep = protected; + + /* + * If the children aren't claiming (all of) the protection + * afforded to them by the parent, distribute the remainder in + * proportion to the (unprotected) memory of each cgroup. That + * way, cgroups that aren't explicitly prioritized wrt each + * other compete freely over the allowance, but they are + * collectively protected from neighboring trees. + * + * We're using unprotected memory for the weight so that if + * some cgroups DO claim explicit protection, we don't protect + * the same bytes twice. + */ + if (!(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)) + return ep; + + if (parent_effective > siblings_protected && usage > protected) { + unsigned long unclaimed; + + unclaimed = parent_effective - siblings_protected; + unclaimed *= usage - protected; + unclaimed /= parent_usage - siblings_protected; + + ep += unclaimed; + } + + return ep; } /** @@ -6321,8 +6362,8 @@ static unsigned long effective_protection(unsigned long usage, enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, struct mem_cgroup *memcg) { + unsigned long usage, parent_usage; struct mem_cgroup *parent; - unsigned long usage; if (mem_cgroup_disabled()) return MEMCG_PROT_NONE; @@ -6347,11 +6388,13 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, goto out; } - memcg->memory.emin = effective_protection(usage, + parent_usage = page_counter_read(&parent->memory); + + memcg->memory.emin = effective_protection(usage, parent_usage, memcg->memory.min, READ_ONCE(parent->memory.emin), atomic_long_read(&parent->memory.children_min_usage)); - memcg->memory.elow = effective_protection(usage, + memcg->memory.elow = effective_protection(usage, parent_usage, memcg->memory.low, READ_ONCE(parent->memory.elow), atomic_long_read(&parent->memory.children_low_usage)); |