The patch titled
Subject: device_cgroup: don't grab mutex in rcu callback
has been added to the -mm tree. Its filename is
device_cgroup-dont-grab-mutex-in-rcu-callback.patch
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------------------------------------------------------
From: Jerry Snitselaar <jerry.snitselaar@xxxxxxxxxx>
Subject: device_cgroup: don't grab mutex in rcu callback
commit 103a197 ("security/device_cgroup: lock assert fails in
dev_exception_clean()") grabs devcgroup_mutex to fix assert failure, but
mutex can't be grabbed in rcu callback. Since there shouldn't be any
other references when css_free is called, mutex isn't needed for list
cleanup in devcgroup_css_free().
Signed-off-by: Jerry Snitselaar <jerry.snitselaar@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Acked-by: Aristeu Rozanski <aris@xxxxxxxxxx>
Cc: James Morris <james.l.morris@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
security/device_cgroup.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
diff -puN security/device_cgroup.c~device_cgroup-dont-grab-mutex-in-rcu-callback security/device_cgroup.c
--- a/security/device_cgroup.c~device_cgroup-dont-grab-mutex-in-rcu-callback
+++ a/security/device_cgroup.c
@@ -159,6 +159,16 @@ static void dev_exception_rm(struct dev_
}
}
+static void __dev_exception_clean(struct dev_cgroup *dev_cgroup)
+{
+ struct dev_exception_item *ex, *tmp;
+
+ list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) {
+ list_del_rcu(&ex->list);
+ kfree_rcu(ex, rcu);
+ }
+}
+
/**
* dev_exception_clean - frees all entries of the exception list
* @dev_cgroup: dev_cgroup with the exception list to be cleaned
@@ -167,14 +177,9 @@ static void dev_exception_rm(struct dev_
*/
static void dev_exception_clean(struct dev_cgroup *dev_cgroup)
{
- struct dev_exception_item *ex, *tmp;
-
lockdep_assert_held(&devcgroup_mutex);
- list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) {
- list_del_rcu(&ex->list);
- kfree_rcu(ex, rcu);
- }
+ __dev_exception_clean(dev_cgroup);
}
/*
@@ -215,9 +220,7 @@ static void devcgroup_css_free(struct cg
struct dev_cgroup *dev_cgroup;
dev_cgroup = cgroup_to_devcgroup(cgroup);
- mutex_lock(&devcgroup_mutex);
- dev_exception_clean(dev_cgroup);
- mutex_unlock(&devcgroup_mutex);
+ __dev_exception_clean(dev_cgroup);
kfree(dev_cgroup);
}
_
Patches currently in -mm which might be from jerry.snitselaar@xxxxxxxxxx are
device_cgroup-dont-grab-mutex-in-rcu-callback.patch
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