diff options
| author | Xiu Jianfeng <xiujianfeng@huawei.com> | 2024-07-30 03:29:20 +0000 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2024-07-30 12:13:19 -1000 |
| commit | d72a00a8485d1cb11ac1a57bf89b02cbd3a405bf (patch) | |
| tree | 6bba6e6e3746edb9350b0b283b7b3d36abc1d567 /kernel/cgroup | |
| parent | d6326047576266991d88639e1e9739a9a9a20ef4 (diff) | |
cgroup/pids: Avoid spurious event notification
Currently when a process in a group forks and fails due to it's
parent's max restriction, all the cgroups from 'pids_forking' to root
will generate event notifications but only the cgroups from
'pids_over_limit' to root will increase the counter of PIDCG_MAX.
Consider this scenario: there are 4 groups A, B, C,and D, the
relationships are as follows, and user is watching on C.pids.events.
root->A->B->C->D
When a process in D forks and fails due to B.max restriction, the
user will get a spurious event notification because when he wakes up
and reads C.pids.events, he will find that the content has not changed.
To address this issue, only the cgroups from 'pids_over_limit' to root
will have their PIDCG_MAX counters increased and event notifications
generated.
Fixes: 385a635cacfe ("cgroup/pids: Make event counters hierarchical")
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup')
| -rw-r--r-- | kernel/cgroup/pids.c | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c index f5cb0ec45b9d..34aa63d7c9c6 100644 --- a/kernel/cgroup/pids.c +++ b/kernel/cgroup/pids.c @@ -244,7 +244,6 @@ static void pids_event(struct pids_cgroup *pids_forking, struct pids_cgroup *pids_over_limit) { struct pids_cgroup *p = pids_forking; - bool limit = false; /* Only log the first time limit is hit. */ if (atomic64_inc_return(&p->events_local[PIDCG_FORKFAIL]) == 1) { @@ -252,20 +251,17 @@ static void pids_event(struct pids_cgroup *pids_forking, pr_cont_cgroup_path(p->css.cgroup); pr_cont("\n"); } - cgroup_file_notify(&p->events_local_file); if (!cgroup_subsys_on_dfl(pids_cgrp_subsys) || - cgrp_dfl_root.flags & CGRP_ROOT_PIDS_LOCAL_EVENTS) + cgrp_dfl_root.flags & CGRP_ROOT_PIDS_LOCAL_EVENTS) { + cgroup_file_notify(&p->events_local_file); return; + } - for (; parent_pids(p); p = parent_pids(p)) { - if (p == pids_over_limit) { - limit = true; - atomic64_inc(&p->events_local[PIDCG_MAX]); - cgroup_file_notify(&p->events_local_file); - } - if (limit) - atomic64_inc(&p->events[PIDCG_MAX]); + atomic64_inc(&pids_over_limit->events_local[PIDCG_MAX]); + cgroup_file_notify(&pids_over_limit->events_local_file); + for (p = pids_over_limit; parent_pids(p); p = parent_pids(p)) { + atomic64_inc(&p->events[PIDCG_MAX]); cgroup_file_notify(&p->events_file); } } |