From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ying Xue Subject: Re: [PATCH 0/6 net-next] rhashtable fixes Date: Fri, 30 Jan 2015 17:56:51 +0800 Message-ID: <54CB5563.9080000@windriver.com> References: <54CB4A95.9060000@windriver.com> <20150130092911.GA2313@casper.infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Cc: , To: Thomas Graf Return-path: Received: from mail.windriver.com ([147.11.1.11]:36730 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757523AbbA3J5T (ORCPT ); Fri, 30 Jan 2015 04:57:19 -0500 In-Reply-To: <20150130092911.GA2313@casper.infradead.org> Sender: netdev-owner@vger.kernel.org List-ID: On 01/30/2015 05:29 PM, Thomas Graf wrote: > On 01/30/15 at 05:10pm, Ying Xue wrote: >> Hi Thomas, >> >> I make sure that my local net-next tree is synchronized to the latest >> version in which the commit fe6a043c535acfec8f8e554536c87923dcb45097 >> ("rhashtable: rhashtable_remove() must unlink in both tbl and >> future_tbl") is already contained, and then I manually applied the whole >> series patches. But when I repeatedly run the test case I originally >> posted, soft lockup happens. Please see its relevant log: > > Right, I see the same soft lockup. Interestingly I cannot trigger it > with the rht test code. I can only trigger it with your Netlink socket > creation stress test. It is definitely related to the deferred worker, > when I disable growing, then the bug disappears. Yes, when I disable expansion, the soft lockup also disappears too. I think that the > expansion leaves a race open in which remove cannot find certain entries > (I verified this by adding a BUG_ON() when rhashtable_remove() could not > find a match). This then keeps an entry on the list which has already > been freed. > > However, I think this was present before these fixes but hidden as the > lockup requires a lot more iterations of your stress test on my > machine. > If you need to some verification for your new patches or do some experiments, please let me know, and I can help to do them. Regards, Ying