From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751246AbbI0QmU (ORCPT ); Sun, 27 Sep 2015 12:42:20 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:48091 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750868AbbI0QmS (ORCPT ); Sun, 27 Sep 2015 12:42:18 -0400 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org Date: Sun, 27 Sep 2015 09:42:11 -0700 From: "Paul E. McKenney" To: Sedat Dilek Cc: Ingo Molnar , Linus Torvalds , LKML Subject: Re: [GIT PULL rcu/urgent] Fix two more 4.3 regressions Message-ID: <20150927164210.GH30373@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20150927073219.GE30373@linux.vnet.ibm.com> <20150927154929.GF30373@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15092716-8236-0000-0000-000012415756 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 27, 2015 at 05:55:43PM +0200, Sedat Dilek wrote: > On Sun, Sep 27, 2015 at 5:49 PM, Paul E. McKenney > wrote: > > On Sun, Sep 27, 2015 at 09:37:05AM +0200, Sedat Dilek wrote: > >> On Sun, Sep 27, 2015 at 9:32 AM, Paul E. McKenney > >> wrote: > >> > On Sun, Sep 27, 2015 at 08:28:39AM +0200, Sedat Dilek wrote: [ . . . ] > Hi Paul :-), > > Here is the stack trace. > > [ 23.045871] BUG: sleeping function called from invalid context at > kernel/workqueue.c:2678 > [ 23.045982] in_atomic(): 0, irqs_disabled(): 1, pid: 1399, name: acpid > [ 23.046064] 3 locks held by acpid/1399: > [ 23.046066] #0: (&evdev->mutex){+.+...}, at: [] > evdev_release+0xbc/0xf0 > [ 23.046081] #1: (&dev->mutex#2){+.+...}, at: [] > input_close_device+0x27/0x70 > [ 23.046093] #2: (hid_open_mut){+.+...}, at: [] > usbhid_close+0x28/0xb0 [usbhid] > [ 23.046106] irq event stamp: 3306 > [ 23.046109] hardirqs last enabled at (3305): [] > _raw_spin_unlock_irq+0x32/0x60 > [ 23.046115] hardirqs last disabled at (3306): [] > del_timer_sync+0x37/0x110 > [ 23.046122] softirqs last enabled at (2704): [] > local_bh_enable+0x9/0x20 > [ 23.046128] softirqs last disabled at (2702): [] > local_bh_disable+0x9/0x20 > [ 23.046136] CPU: 2 PID: 1399 Comm: acpid Not tainted > 4.3.0-rc3-3-llvmlinux-amd64 #1 > [ 23.046139] Hardware name: SAMSUNG ELECTRONICS CO., LTD. > 530U3BI/530U4BI/530U4BH/530U3BI/530U4BI/530U4BH, BIOS 13XK 03/28/2013 > [ 23.046143] ffff8800d36ee948 0000000000000092 0000000000000000 > ffff8800bbacfae8 > [ 23.046151] ffffffff8149adad ffff8800bbacfb18 ffffffff810cd1ea > ffffffff81c56f0a > [ 23.046158] ffff8800c22dc400 0000000000000000 0000000000000a76 > ffff8800bbacfb58 > [ 23.046165] Call Trace: > [ 23.046172] [] dump_stack+0x7d/0xa0 > [ 23.046177] [] ___might_sleep+0x28a/0x2a0 > [ 23.046182] [] __might_sleep+0x4f/0xc0 > [ 23.046187] [] start_flush_work+0x2f/0x290 > [ 23.046192] [] flush_work+0x5c/0x80 > [ 23.046195] [] ? flush_work+0x1a/0x80 > [ 23.046202] [] ? trace_hardirqs_off+0xd/0x10 > [ 23.046206] [] ? try_to_grab_pending+0x48/0x360 > [ 23.046211] [] ? _raw_spin_lock_irqsave+0x73/0x80 > [ 23.046216] [] __cancel_work_timer+0x179/0x260 > [ 23.046221] [] ? _raw_spin_unlock_irqrestore+0x52/0x80 > [ 23.046226] [] ? try_to_del_timer_sync+0xad/0xc0 > [ 23.046230] [] cancel_work_sync+0x18/0x20 > [ 23.046237] [] usbhid_close+0x75/0xb0 [usbhid] > [ 23.046245] [] hidinput_close+0x31/0x40 [hid] > [ 23.046251] [] ? hidinput_open+0x40/0x40 [hid] > [ 23.046256] [] input_close_device+0x48/0x70 > [ 23.046261] [] evdev_release+0xd6/0xf0 > [ 23.046267] [] __fput+0x107/0x240 > [ 23.046271] [] ____fput+0x16/0x20 > [ 23.046276] [] task_work_run+0x6c/0xe0 > [ 23.046282] [] prepare_exit_to_usermode+0x117/0x120 > [ 23.046287] [] syscall_return_slowpath+0x231/0x2a0 > [ 23.046292] [] ? filp_close+0x65/0x90 > [ 23.046298] [] ? trace_hardirqs_on_caller+0x19/0x290 > [ 23.046303] [] ? trace_hardirqs_on_thunk+0x17/0x19 > [ 23.046308] [] int_ret_from_sys_call+0x25/0x9f > > Can you give help on how to "debug" this? > > I switched from full-dynticks to simple cpu-accounting which did not help. > But this was only a suspicion as Jiri pointed to the possibility > del_timer_sync() could have get some mis-optimization. > > So, more empty head here. I am not familiar with the "hardirqs last enabled" debug output, but I am guessing that hardirqs are disabled because the "last disabled" number is greater than the "last enabled" number. So if I understand correctly, something somewhere up the call stack has irqs disabled, but is calling a function that needs them enabled. A quick look at usbhid_close() shows no problem, but then again, I am looking at the v4.2 version rather than whatever you are testing. But v4.3-rc2 looks the same. Looks like you are already in contact with Jiri, which is good. Another thing to try would be to insert might_sleep() calls, after usbhid_close(), since it enables irqs explicitly, but before the call to flush_work(). Jiri's comment can be interpreted as a suggestion to insert a might_sleep() in try_to_del_timer_sync(), though __cancel_work_timer() wouldn't be a bad place to try as well, just before its call to flush_work(). Thanx, Paul > - Sedat - > > >> $ grep LOCKDEP /boot/config-4.3.0-rc2-438.1-llvmlinux-amd64 > >> CONFIG_LOCKDEP_SUPPORT=y > >> CONFIG_LOCKDEP=y > >> # CONFIG_DEBUG_LOCKDEP is not set > >> > >> So, CLANG is a bit different compiler :-). > > > > True enough. Good to have more than one, though. > > > > Thanx, Paul > > > >> Thanks for taking care. > >> > >> Regards, > >> - Sedat - > >> > >> >> > >> >> [1] http://marc.info/?l=linux-kernel&m=144332758307978&w=2 > >> >> [2] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/patch/?id=66e8c57da6bf6b847a48a5a6fda59512f733ed78 > >> >> [3] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/patch/?id=19a5ecde086a6a5287978b12ae948fa691b197b7 > >> >> > >> > > >> > > >