From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755929Ab0DFQUH (ORCPT ); Tue, 6 Apr 2010 12:20:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13725 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753018Ab0DFQUC (ORCPT ); Tue, 6 Apr 2010 12:20:02 -0400 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 From: David Howells To: paulmck@linux.vnet.ibm.com, npiggin@suse.de, corbet@lwn.net cc: dhowells@redhat.com, linux-kernel@vger.kernel.org, linux-cachefs@redhat.com Subject: An incorrect assumption over radix_tree_tag_get() Date: Tue, 06 Apr 2010 17:19:49 +0100 Message-ID: <23428.1270570789@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I think I've made a bad assumption over my usage of radix_tree_tag_get() in fs/fscache/page.c. I've assumed that radix_tree_tag_get() is protected from radix_tree_tag_set() and radix_tree_tag_clear() by the RCU read lock. However, now I'm not so sure. I think it's only protected against removal of part of the tree. Can you confirm? David