From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Marek Lindner Date: Tue, 26 Feb 2013 13:52:46 +0800 References: <5127A2AF.9030502@oracle.com> <20130222170621.GU3523@ritirata.org> <5127BAD2.1040007@oracle.com> In-Reply-To: <5127BAD2.1040007@oracle.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201302261352.47191.lindner_marek@yahoo.de> Subject: Re: [B.A.T.M.A.N.] batman-adv: gpf in batadv_slide_own_bcast_window Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: b.a.t.m.a.n@lists.open-mesh.org Cc: netdev@vger.kernel.org, "linux-kernel@vger.kernel.org" , Simon Wunderlich , Dave Jones , Sasha Levin , "David S. Miller" On Saturday, February 23, 2013 02:37:06 Sasha Levin wrote: > I'm confused about how batadv_orig_hash_del_if removes an interface from > the hashtable. I see the hashtable is using rcu to protect it, but when we > delete an entry we free it straight away by calling > batadv_orig_node_del_if() and not going through kfree_rcu(). > > Is there a reason behind doing that, or might it be the cause of the > problem we're seeing here? Maybe I am overlooking something but it seems to me access to this memory is protected by the same lock: orig_node->ogm_cnt_lock Before batadv_orig_node_del_if() is called this lock is acquired and batadv_slide_own_bcast_window() also attempts acquire the orig_node- >ogm_cnt_lock spinlock before writing to this chunk of memory. Do we know for certain that batadv_orig_hash_del_if() is involved or is that a guess at this point ? If you ask me the next for-loop in batadv_orig_hash_del_if() looks more suspicious than the first one. The interfaces get renumbered without any protection. Could be a regression from the orig_hash_lock removal (the comments refer to a now inexisting lock). Cheers, Marek