From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx169.postini.com [74.125.245.169]) by kanga.kvack.org (Postfix) with SMTP id 2B3F76B002C for ; Thu, 2 Feb 2012 18:01:06 -0500 (EST) Received: by yhoo22 with SMTP id o22so1800795yho.14 for ; Thu, 02 Feb 2012 15:01:05 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <4F2AB614.1060907@de.ibm.com> References: <4F2AB614.1060907@de.ibm.com> From: KOSAKI Motohiro Date: Thu, 2 Feb 2012 18:00:45 -0500 Message-ID: Subject: Re: ksm/memory hotplug: lockdep warning for ksm_thread_mutex vs. (memory_chain).rwsem Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: gerald.schaefer@de.ibm.com Cc: Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Martin Schwidefsky , Heiko Carstens , Andrea Arcangeli , Chris Wright , Izik Eidus , KAMEZAWA Hiroyuki 2012/2/2 Gerald Schaefer : > Setting a memory block offline triggers the following lockdep warning. This > looks exactly like the issue reported by Kosaki Motohiro in > https://lkml.org/lkml/2010/10/25/110. Seems like the resulting commit a0b0f58cdd > did not fix the lockdep warning. I'm able to reproduce it with current 3.3.0-rc2 > as well as 2.6.37-rc4-00147-ga0b0f58. > > I'm not familiar with lockdep annotations, but I tried using down_read_nested() > for (memory_chain).rwsem, similar to the mutex_lock_nested() which was > introduced for ksm_thread_mutex, but that didn't help. Heh, interesting. Simple question, do you have any user visible buggy behavior? or just false positive warn issue? *_nested() is just hacky trick. so, any change may break their lie. Anyway I'd like to dig this one. thanks for reporting. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org