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Message-Id: <20221018000940.2731329-5-sashal@kernel.org>
Date: Mon, 17 Oct 2022 20:09:24 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Tejun Heo <tj@...nel.org>,
Abhishek Shah <abhishek.shah@...umbia.edu>,
Gabriel Ryan <gabe@...columbia.edu>,
Christian Brauner <brauner@...nel.org>,
Sasha Levin <sashal@...nel.org>, lizefan.x@...edance.com,
hannes@...xchg.org, cgroups@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 05/21] cgroup: Remove data-race around cgrp_dfl_visible
From: Tejun Heo <tj@...nel.org>
[ Upstream commit dc79ec1b232ad2c165d381d3dd2626df4ef9b5a4 ]
There's a seemingly harmless data-race around cgrp_dfl_visible detected by
kernel concurrency sanitizer. Let's remove it by throwing WRITE/READ_ONCE at
it.
Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-by: Abhishek Shah <abhishek.shah@...umbia.edu>
Cc: Gabriel Ryan <gabe@...columbia.edu>
Reviewed-by: Christian Brauner (Microsoft) <brauner@...nel.org>
Link: https://lore.kernel.org/netdev/20220819072256.fn7ctciefy4fc4cu@wittgenstein/
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
kernel/cgroup/cgroup.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 4b19f7fc4deb..1dd45a1c1acc 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -2152,7 +2152,7 @@ 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;
@@ -6067,7 +6067,7 @@ 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);
--
2.35.1
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