This is a note to let you know that I've just added the patch titled
device_cgroup: Fix RCU list debugging warning
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
device_cgroup-fix-rcu-list-debugging-warning.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1d85cd0a270d0aac63c00811b7e0090848029814
Author: Amol Grover <frextrite@xxxxxxxxx>
Date: Mon Apr 6 16:29:50 2020 +0530
device_cgroup: Fix RCU list debugging warning
[ Upstream commit bc62d68e2a0a69fcdcf28aca8edb01abf306b698 ]
exceptions may be traversed using list_for_each_entry_rcu()
outside of an RCU read side critical section BUT under the
protection of decgroup_mutex. Hence add the corresponding
lockdep expression to fix the following false-positive
warning:
[ 2.304417] =============================
[ 2.304418] WARNING: suspicious RCU usage
[ 2.304420] 5.5.4-stable #17 Tainted: G E
[ 2.304422] -----------------------------
[ 2.304424] security/device_cgroup.c:355 RCU-list traversed in non-reader section!!
Signed-off-by: Amol Grover <frextrite@xxxxxxxxx>
Signed-off-by: James Morris <jmorris@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 725674f3276d3..5d7bb91c64876 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -352,7 +352,8 @@ static bool match_exception_partial(struct list_head *exceptions, short type,
{
struct dev_exception_item *ex;
- list_for_each_entry_rcu(ex, exceptions, list) {
+ list_for_each_entry_rcu(ex, exceptions, list,
+ lockdep_is_held(&devcgroup_mutex)) {
if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK))
continue;
if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR))
