diff options
| author | Natalie Vock <natalie.vock@gmx.de> | 2026-08-04 10:25:17 +0200 |
|---|---|---|
| committer | Natalie Vock <nat@pixelcluster.dev> | 2026-08-05 10:34:42 +0200 |
| commit | 34f3e259925382cd87187dd426d3918379c6144e (patch) | |
| tree | a0dbd3deda4bfba08b8096a41053dcc596278644 /include | |
| parent | dd517e49a3123f868151ff1a193add8e10ae69ba (diff) | |
cgroup,cgroup/dmem: Add (dmem_)cgroup_common_ancestor helper
This helps to find a common subtree of two resources, which is important
when determining whether it's helpful to evict one resource in favor of
another.
To facilitate this, add a common helper to find the ancestor of two
cgroups using each cgroup's ancestor array.
Tested-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Reviewed-by: Maarten Lankhorst <dev@lankhorst.se>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Natalie Vock <natalie.vock@gmx.de>
Link: https://patch.msgid.link/20260804-dmemcg-aggressive-protect-v8-2-07af96681bf8@gmx.de
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cgroup.h | 21 | ||||
| -rw-r--r-- | include/linux/cgroup_dmem.h | 9 |
2 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index f2aa46a4f871..83a17ded1c51 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -624,6 +624,27 @@ static inline struct cgroup *cgroup_ancestor(struct cgroup *cgrp, } /** + * cgroup_common_ancestor - find common ancestor of two cgroups + * @a: first cgroup to find common ancestor of + * @b: second cgroup to find common ancestor of + * + * Find the first cgroup that is an ancestor of both @a and @b, if it exists + * and return a pointer to it. If such a cgroup doesn't exist, return NULL. + * + * This function is safe to call as long as both @a and @b are accessible. + */ +static inline struct cgroup *cgroup_common_ancestor(struct cgroup *a, + struct cgroup *b) +{ + int level; + + for (level = min(a->level, b->level); level >= 0; level--) + if (a->ancestors[level] == b->ancestors[level]) + return a->ancestors[level]; + return NULL; +} + +/** * task_under_cgroup_hierarchy - test task's membership of cgroup ancestry * @task: the task to be tested * @ancestor: possible ancestor of @task's cgroup diff --git a/include/linux/cgroup_dmem.h b/include/linux/cgroup_dmem.h index 1a88cd0c9eb0..9d72457c4cb9 100644 --- a/include/linux/cgroup_dmem.h +++ b/include/linux/cgroup_dmem.h @@ -28,6 +28,8 @@ bool dmem_cgroup_below_min(struct dmem_cgroup_pool_state *root, struct dmem_cgroup_pool_state *test); bool dmem_cgroup_below_low(struct dmem_cgroup_pool_state *root, struct dmem_cgroup_pool_state *test); +struct dmem_cgroup_pool_state *dmem_cgroup_get_common_ancestor(struct dmem_cgroup_pool_state *a, + struct dmem_cgroup_pool_state *b); void dmem_cgroup_pool_state_put(struct dmem_cgroup_pool_state *pool); #else @@ -75,6 +77,13 @@ static inline bool dmem_cgroup_below_low(struct dmem_cgroup_pool_state *root, return false; } +static inline +struct dmem_cgroup_pool_state *dmem_cgroup_get_common_ancestor(struct dmem_cgroup_pool_state *a, + struct dmem_cgroup_pool_state *b) +{ + return NULL; +} + static inline void dmem_cgroup_pool_state_put(struct dmem_cgroup_pool_state *pool) { } |