On Mon, Aug 22, 2022 at 01:04:58PM -0400, Gabriel Ryan wrote: > Hi Christian, > > We ran a quick test and confirm your suggestion would eliminate the > data race alert we observed. If the data race is benign (and it > appears to be), using WRITE_ONCE(cgrp_dfl_visible, true) instead of > cmpxchg in cgroup_get_tree() would probably also be ok. I don't see how the data race can lead to anything but would the following work? Thanks. diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index ffaccd6373f1e..a90fdba881bdb 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2172,7 +2172,7 @@ static int cgroup_get_tree(struct fs_context *fc) struct cgroup_fs_context *ctx = cgroup_fc2context(fc); int ret; - cgrp_dfl_visible = true; + WRITE_ONCE(cgrp_dfl_visible, true); cgroup_get_live(&cgrp_dfl_root.cgrp); ctx->root = &cgrp_dfl_root; @@ -6056,7 +6056,7 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, struct cgroup *cgrp; int ssid, count = 0; - if (root == &cgrp_dfl_root && !cgrp_dfl_visible) + if (root == &cgrp_dfl_root && !READ_ONCE(cgrp_dfl_visible)) continue; seq_printf(m, "%d:", root->hierarchy_id); -- tejun
