Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933491AbcLIPMe (ORCPT ); Fri, 9 Dec 2016 10:12:34 -0500 Received: from mail-wm0-f43.google.com ([74.125.82.43]:36936 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932917AbcLIPMc (ORCPT ); Fri, 9 Dec 2016 10:12:32 -0500 Date: Fri, 9 Dec 2016 16:12:29 +0100 From: Michal Hocko To: Tejun Heo Cc: LKML Subject: WARNING: CPU: 3 PID: 1568 at kernel/sched/core.c:7738 __might_sleep+0x69/0x7e Message-ID: <20161209151229.GD4334@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2797 Lines: 61 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. Thanks! -- Michal Hocko SUSE Labs