Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758950Ab2KBXK6 (ORCPT ); Fri, 2 Nov 2012 19:10:58 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:35083 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750928Ab2KBXK4 (ORCPT ); Fri, 2 Nov 2012 19:10:56 -0400 MIME-Version: 1.0 In-Reply-To: <2859519.IO8aRDjQvR@vostro.rjw.lan> References: <2471412.ilAVQkroSv@vostro.rjw.lan> <2859519.IO8aRDjQvR@vostro.rjw.lan> From: Linus Torvalds Date: Fri, 2 Nov 2012 16:10:34 -0700 X-Google-Sender-Auth: KIisW5roydiuEhExYHzo5X1LXC4 Message-ID: Subject: Re: Linux 3.7-rc3 To: "Rafael J. Wysocki" Cc: Daniel Vetter , Linux Kernel Mailing List , Linux PM list , Greg Kroah-Hartman , David Airlie , Michal Hocko , Jiri Kosina , Ingo Molnar , Peter Zijlstra Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1584 Lines: 37 On Fri, Nov 2, 2012 at 3:43 PM, Rafael J. Wysocki wrote: > > Well, not everything is rosy in the suspend land, though. This is a > failure to freeze khubd during the second in a row attempt to suspend to > RAM (your current tree): Ugh. So khubd is blocked in usb_start_wait_urb(), and apparently the timeout for that block is longer than the freezing timeout. There's a comment about why khubd needs to be freezable, but I wonder if that whole thing isn't doing something wrong. Causing the suspend to fail is definitely always the wrong thing. Greg? > [ 125.780766] [ INFO: suspicious RCU usage. ] > [ 125.780804] 3.7.0-rc3+ #988 Not tainted > [ 125.780838] ------------------------------- > [ 125.780875] /home/rafael/src/linux/kernel/sched/core.c:4497 suspicious rcu_dereference_check() usage! Heh. The RCU usage is from the debug printout from sched_show_task(), so it's "related", but it's a totally independent issue. It's apparently because we've not done a "rcu_read_lock()" around that sequence, but I seriously doubt we care. But it's technically a real bug - even if the fix might be to just not print out the parent pid (or to just ignore the bug and turn the rcu dereference into an ACCESS_ONCE() or something. Ingo, Peter, any comments about that sched/core.c:4497 RCU usage? Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/