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Groups > linux.kernel > #1495484

Re: [PATCH] Fix suspicious RCU usage in nfs_idmap_get_key.

From David Howells <dhowells@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH] Fix suspicious RCU usage in nfs_idmap_get_key.
Date 2016-10-04 17:50 +0200
Message-ID <soA8F-4HM-1@gated-at.bofh.it> (permalink)
References <soy6R-3iO-9@gated-at.bofh.it>
Organization Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

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Artem Savkov <asavkov@redhat.com> wrote:

> nfs_idmap_get_key doesn't hold rkey->sem when calling user_key_payload
> resulting in a "suspicious RCU usage" lockdep splat. It does, however hold
> rcu_read_lock, so it either needs to use unprotected rcu_dereference, or take
> rkey->sem instead of rcu_read_lock.

This shouldn't be using rkey->sem.  user_key_payload() should do sufficient
RCU magic that rcu_read_lock() is sufficient.  Can you please include the RCU
splat?  It's possible user_key_payload() is wrong.

David

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Thread

[PATCH] Fix suspicious RCU usage in nfs_idmap_get_key. Artem Savkov <asavkov@redhat.com> - 2016-10-04 15:40 +0200
  Re: [PATCH] Fix suspicious RCU usage in nfs_idmap_get_key. David Howells <dhowells@redhat.com> - 2016-10-04 17:50 +0200
    Re: [PATCH] Fix suspicious RCU usage in nfs_idmap_get_key. Artem Savkov <asavkov@redhat.com> - 2016-10-04 18:00 +0200

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