Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932275AbcLLWDx (ORCPT ); Mon, 12 Dec 2016 17:03:53 -0500 Received: from mail-yw0-f194.google.com ([209.85.161.194]:34152 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751702AbcLLWDw (ORCPT ); Mon, 12 Dec 2016 17:03:52 -0500 Date: Mon, 12 Dec 2016 17:03:49 -0500 From: Tejun Heo To: Michal Hocko Cc: LKML , Shaohua Li Subject: Re: WARNING: CPU: 3 PID: 1568 at kernel/sched/core.c:7738 __might_sleep+0x69/0x7e Message-ID: <20161212220349.GK13864@htj.duckdns.org> References: <20161209151229.GD4334@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161209151229.GD4334@dhcp22.suse.cz> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3158 Lines: 68 Hello, Michal. On Fri, Dec 09, 2016 at 04:12:29PM +0100, Michal Hocko wrote: > Hi Tejun, > I am seeing the following warning during boot in my kvm testing > environment: > [ 3.549649] WARNING: CPU: 3 PID: 1568 at kernel/sched/core.c:7738 __might_sleep+0x69/0x7e > [ 3.551279] do not call blocking ops when !TASK_RUNNING; state=2 set at [] prepare_to_wait+0x65/0xac > [ 3.553354] Modules linked in: > [ 3.554032] CPU: 3 PID: 1568 Comm: modprobe Not tainted 4.9.0-rc8-nofstest5-next-20161209-00013-g3134766e941a #1018 > [ 3.556099] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014 > [ 3.557330] Call Trace: > [ 3.557330] dump_stack+0x68/0x92 > [ 3.557330] __warn+0xc2/0xdd > [ 3.557330] warn_slowpath_fmt+0x4b/0x53 > [ 3.557330] ? prepare_to_wait+0x65/0xac > [ 3.557330] ? prepare_to_wait+0x65/0xac > [ 3.557330] __might_sleep+0x69/0x7e > [ 3.557330] do_ide_request+0x47/0x540 > [ 3.557330] ? __lock_is_held+0x47/0x7a > [ 3.557330] ? hrtimer_try_to_cancel+0x15f/0x1c6 > [ 3.557330] ? _raw_spin_unlock_irqrestore+0x4c/0x61 > [ 3.557330] __blk_run_queue+0x31/0x3a > [ 3.557330] cfq_insert_request+0x331/0x429 > [ 3.557330] __elv_add_request+0x2bb/0x346 > [ 3.557330] blk_flush_plug_list+0x1da/0x21f > [ 3.557330] ? bit_wait+0x50/0x50 > [ 3.557330] io_schedule_timeout+0x47/0x102 > [ 3.557330] bit_wait_io+0x1b/0x5a > [ 3.557330] __wait_on_bit+0x4d/0x7b > [ 3.557330] out_of_line_wait_on_bit+0x72/0x7d > [ 3.557330] ? bit_wait+0x50/0x50 > [ 3.557330] ? autoremove_wake_function+0x4e/0x4e > [ 3.557330] __wait_on_buffer+0x40/0x43 > [ 3.557330] bh_submit_read+0x60/0x72 > [ 3.557330] ext4_get_branch+0x91/0x115 > [ 3.557330] ext4_ind_map_blocks+0x181/0xa16 > [ 3.557330] ? __lock_is_held+0x47/0x7a > [ 3.557330] ? lock_acquire+0x133/0x1c7 > [ 3.557330] ext4_map_blocks+0x120/0x4ca > [ 3.557330] ext4_mpage_readpages+0x2a7/0x70a > [ 3.557330] ext4_readpages+0x33/0x35 > [ 3.557330] __do_page_cache_readahead+0x239/0x32a > [ 3.557330] filemap_fault+0x180/0x602 > [ 3.557330] ? filemap_fault+0x180/0x602 > [ 3.557330] ext4_filemap_fault+0x37/0x4b > [ 3.557330] __do_fault+0x1f/0x94 > [ 3.557330] handle_mm_fault+0x946/0xfca > [ 3.557330] __do_page_fault+0x361/0x518 > [ 3.557330] do_page_fault+0x42/0x5f > [ 3.557330] page_fault+0x22/0x30 > > At first I thought this would be related to you recent work > http://lkml.kernel.org/r/1477673892-28940-1-git-send-email-tj@kernel.org > but that doesn't seem to be in the linux-next I am using as a base. > io_schedule_timeout is on the stack though so you might have an idea > what is going on here. That might_sleep check has been added a long ago > 02e7cf8f8488 ("ide-cd,atapi: use bio for internal commands") in 2.6.31 > so I am wondering what has changed since than. 10d784eae2b4 ("sched: always use blk_schedule_flush_plug in io_schedule_out") seems related. might_sleep is complaining that it's being called while !TASK_RUNNING. Shaohua, any ideas? Thanks. -- tejun