From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>

The sparse checking for rcu_assign_pointer() was recently upgraded
to reject non-__kernel address spaces.  This also rejects __rcu,
which is almost always the right thing to do.  However, the use in
notifier_chain_unregister() is legitimate: It is deleting an element
from an RCU-protected list, and all elements of this list are already
visible to caller.

This commit therefore silences this false positive by laundering the
pointer using rcu_access_pointer() as suggested by Josh Triplett.

Reported-by: kbuild test robot <fengguang...@intel.com>
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
---
 kernel/notifier.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/notifier.c b/kernel/notifier.c
index 2d5cc4c..1857c71 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -51,7 +51,7 @@ static int notifier_chain_unregister(struct notifier_block 
**nl,
 {
        while ((*nl) != NULL) {
                if ((*nl) == n) {
-                       rcu_assign_pointer(*nl, n->next);
+                       rcu_assign_pointer(*nl, rcu_access_pointer(n->next));
                        return 0;
                }
                nl = &((*nl)->next);
-- 
1.8.1.5

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