linux-kernel - de-reference of rcu pointers (sparse warnings)

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Message-ID: <d0e13f6d93323acd3df7a6b92a56ab13@codethink.co.uk>
Date:   Tue, 05 Nov 2019 08:13:13 +0000
From:   Ben Dooks <ben.dooks@...ethink.co.uk>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arch@...r.kernel.org
Subject: de-reference of rcu pointers (sparse warnings)

There are a few places in the kenrnel which directly de-reference
pointers marked as "noderef" such sa rcu or percpu. In the case
of rcu, one example is:

kernel/fork.c:2146:32: warning: incorrect type in assignment (different 
address spaces)
kernel/fork.c:2146:32:    expected struct task_struct [noderef] <asn:4> 
*real_parent
kernel/fork.c:2146:32:    got struct task_struct *task

this looks fairly non-trivial to fix given there's a mix of __rcu and 
non-__rcu
attributed variables.

Does anyone have an idea how to go about fixing these, if possible?

-- 
Ben