Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937411AbdLRRf0 (ORCPT ); Mon, 18 Dec 2017 12:35:26 -0500 Received: from mga07.intel.com ([134.134.136.100]:27928 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934846AbdLRRfS (ORCPT ); Mon, 18 Dec 2017 12:35:18 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.45,422,1508828400"; d="scan'208";a="3705740" Subject: Re: 995d11c4c0 ("drm: rework delayed connector cleanup in .."): WARNING: possible circular locking dependency detected To: Daniel Vetter , kernel test robot , Linux Kernel Mailing List , Peter Zijlstra Cc: LKP , wfg@linux.intel.com, intel-gfx References: <5a34f89f.W7S7bjGiKJVPRZqa%fengguang.wu@intel.com> From: Maarten Lankhorst Message-ID: Date: Mon, 18 Dec 2017 18:35:11 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11392 Lines: 183 Op 18-12-17 om 08:08 schreef Daniel Vetter: > Hm, the bisect looks funny. Only way I can explain that is that my > patch fixed a pre-existing lockdep splat, and uncovered the issue in > the ww-mutex self tests. That one is uncovered by the new > cross-release lockdep checks in 4.15. > > Anyway I think this is an issue with the ww-mutex tests, not my patch > (none of the code I touched is anywhere in the backtraces), adding > relevant people. > -Daniel > > > On Sat, Dec 16, 2017 at 11:42 AM, kernel test robot > wrote: >> Greetings, >> >> 0day kernel testing robot got the below dmesg and the first bad commit is >> >> https://github.com/0day-ci/linux/commits/Daniel-Vetter/drm-rework-delayed-connector-cleanup-in-connector_iter/20171216-120456 >> >> commit 995d11c4c0f1aa99d0f97fb747a4e0d04121cde2 >> Author: Daniel Vetter >> AuthorDate: Wed Dec 13 11:45:53 2017 +0100 >> Commit: 0day robot >> CommitDate: Sat Dec 16 12:04:58 2017 +0800 >> >> drm: rework delayed connector cleanup in connector_iter >> >> PROBE_DEFER also uses system_wq to reprobe drivers, which means when >> that again fails, and we try to flush the overall system_wq (to get >> all the delayed connectore cleanup work_struct completed), we >> deadlock. >> >> Fix this by using just a single cleanup work, so that we can only >> flush that one and don't block on anything else. That means a free >> list plus locking, a standard pattern. >> >> Fixes: a703c55004e1 ("drm: safely free connectors from connector_iter") >> Fixes: 613051dac40d ("drm: locking&new iterators for connector_list") >> Cc: Ben Widawsky >> Cc: Dave Airlie >> Cc: Chris Wilson >> Cc: Sean Paul >> Cc: # v4.11+: 613051dac40d ("drm: locking&new iterators for connector_list" >> Cc: # v4.11+ >> Cc: Daniel Vetter >> Cc: Jani Nikula >> Cc: Gustavo Padovan >> Cc: David Airlie >> Cc: Javier Martinez Canillas >> Cc: Shuah Khan >> Cc: Guillaume Tucker >> Cc: Mark Brown >> Cc: Kevin Hilman >> Cc: Matt Hart >> Cc: Thierry Escande >> Cc: Tomeu Vizoso >> Cc: Enric Balletbo i Serra >> Signed-off-by: Daniel Vetter >> >> 50c4c4e268 Linux 4.15-rc3 >> 995d11c4c0 drm: rework delayed connector cleanup in connector_iter >> +-------------------------------------------------------+-----------+------------+ >> | | v4.15-rc3 | 995d11c4c0 | >> +-------------------------------------------------------+-----------+------------+ >> | boot_successes | 1 | 0 | >> | boot_failures | 82 | 15 | >> | WARNING:possible_circular_locking_dependency_detected | 82 | 15 | >> | kernel_BUG_at_lib/list_debug.c | 0 | 15 | >> | invalid_opcode:#[##] | 0 | 15 | >> | RIP:__list_add_valid | 0 | 15 | >> | Kernel_panic-not_syncing:Fatal_exception | 0 | 15 | >> +-------------------------------------------------------+-----------+------------+ >> >> [ 3.252870] CPU feature 'AVX registers' is not supported. >> [ 3.261404] AVX2 or AES-NI instructions are not detected. >> [ 3.262708] AVX2 instructions are not detected. >> [ 3.770347] >> [ 3.773471] ====================================================== >> [ 3.773471] WARNING: possible circular locking dependency detected >> [ 3.773471] 4.15.0-rc3-00001-g995d11c #1 Not tainted >> [ 3.773471] ------------------------------------------------------ >> [ 3.773471] swapper/0/1 is trying to acquire lock: >> [ 3.773471] (ww_class_mutex){+.+.}, at: [<00000000134bc923>] test_abba+0x120/0x21e >> [ 3.773471] >> [ 3.773471] but now in release context of a crosslock acquired at the following: >> [ 3.773471] ((completion)&abba.a_ready){+.+.}, at: [<00000000ea3fc8c8>] test_abba_work+0x43/0xab >> [ 3.773471] >> [ 3.773471] which lock already depends on the new lock. >> [ 3.773471] >> [ 3.773471] the existing dependency chain (in reverse order) is: >> [ 3.773471] >> [ 3.773471] -> #1 ((completion)&abba.a_ready){+.+.}: >> [ 3.773471] __wait_for_common+0x55/0x1fe >> [ 3.773471] test_abba_work+0x43/0xab >> [ 3.773471] process_one_work+0x1d4/0x310 >> [ 3.773471] worker_thread+0x1aa/0x25d >> [ 3.773471] kthread+0x120/0x128 >> [ 3.773471] ret_from_fork+0x24/0x30 >> [ 3.773471] >> [ 3.773471] -> #0 (ww_class_mutex){+.+.}: >> [ 3.773471] test_abba+0x120/0x21e >> [ 3.773471] test_ww_mutex_init+0x88/0x2fd >> [ 3.773471] do_one_initcall+0x94/0x149 >> [ 3.773471] kernel_init_freeable+0x12a/0x1a6 >> [ 3.773471] kernel_init+0x5/0xe1 >> [ 3.773471] >> [ 3.773471] other info that might help us debug this: >> [ 3.773471] >> [ 3.773471] Possible unsafe locking scenario by crosslock: >> [ 3.773471] >> [ 3.773471] CPU0 CPU1 >> [ 3.773471] ---- ---- >> [ 3.773471] lock(ww_class_mutex); >> [ 3.773471] lock((completion)&abba.a_ready); >> [ 3.773471] lock(ww_class_mutex); >> [ 3.773471] unlock((completion)&abba.a_ready); >> [ 3.773471] >> [ 3.773471] *** DEADLOCK *** >> [ 3.773471] >> [ 3.773471] 3 locks held by swapper/0/1: >> [ 3.773471] #0: (ww_class_acquire){+.+.}, at: [<00000000f90b2f9f>] test_abba+0x115/0x21e >> [ 3.773471] #1: (ww_class_mutex){+.+.}, at: [<00000000134bc923>] test_abba+0x120/0x21e >> [ 3.773471] #2: (&x->wait#7){....}, at: [<0000000092c10ea9>] complete+0x13/0x4b >> [ 3.773471] >> [ 3.773471] stack backtrace: >> [ 3.773471] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.15.0-rc3-00001-g995d11c #1 >> [ 3.773471] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 >> [ 3.773471] Call Trace: >> [ 3.773471] dump_stack+0x79/0xab >> [ 3.773471] print_circular_bug+0x2a1/0x2af >> [ 3.773471] check_prev_add+0x88/0x229 >> [ 3.773471] ? __lockdep_init_map+0x1aa/0x1aa >> [ 3.773471] ? __lock_acquire+0xd7c/0xe2c >> [ 3.773471] ? _raw_spin_unlock_irq+0x29/0x32 >> [ 3.773471] ? lock_commit_crosslock+0x32e/0x3af >> [ 3.773471] lock_commit_crosslock+0x32e/0x3af >> [ 3.773471] complete+0x1f/0x4b >> [ 3.773471] test_abba+0x128/0x21e >> [ 3.773471] ? test_cycle_work+0xa1/0xa1 >> [ 3.773471] ? test_abba_work+0x43/0xab >> [ 3.773471] ? set_debug_rodata+0xc/0xc >> [ 3.773471] test_ww_mutex_init+0x88/0x2fd >> [ 3.773471] ? set_debug_rodata+0xc/0xc >> [ 3.773471] ? lockdep_proc_init+0x51/0x51 >> [ 3.773471] ? set_debug_rodata+0xc/0xc >> [ 3.773471] do_one_initcall+0x94/0x149 >> [ 3.773471] ? set_debug_rodata+0xc/0xc >> [ 3.773471] kernel_init_freeable+0x12a/0x1a6 >> [ 3.773471] ? rest_init+0xba/0xba >> [ 3.773471] kernel_init+0x5/0xe1 >> [ 3.773471] ret_from_fork+0x24/0x30 >> [ 4.213498] tsc: Refined TSC clocksource calibration: 2593.993 MHz >> [ 4.214153] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x256411d258c, max_idle_ns: 440795337342 ns >> [ 9.875268] rcu-torture:--- Start of test: nreaders=1 nfakewriters=4 stat_interval=60 verbose=1 test_no_idle_hz=1 shuffle_interval=3 stutter=5 irqreader=1 fqs_duration=0 fqs_holdoff=0 fqs_stutter=3 test_boost=1/0 test_boost_interval=7 test_boost_duration=4 shutdown_secs=0 stall_cpu=0 stall_cpu_holdoff=10 stall_cpu_irqsoff=0 n_barrier_cbs=0 onoff_interval=0 onoff_holdoff=0 >> [ 9.878594] rcu-torture: Creating rcu_torture_writer task >> [ 9.886729] rcu-torture: Creating rcu_torture_fakewriter task Looks like a selftest that should throw a warn, but not sure why it returns a kernel warning instead of a simple PASS.. >> # HH:MM RESULT GOOD BAD GOOD_BUT_DIRTY DIRTY_NOT_BAD >> git bisect start 8174afd657ed57f8ea96940235a2f5a5fec10847 50c4c4e268a2d7a3e58ebb698ac74da0de40ae36 -- >> git bisect bad 26cfe9440f51706d7a9639c79f59372b948637e6 # 15:20 B 0 3 16 0 Merge 'mvebu/for-next' into devel-spot-201712161301 >> git bisect bad 0e185f01383d4fdc5827ccd4d894b754234c5e31 # 15:54 B 0 4 17 0 Merge 'linux-review/Nicolin-Chen/ASoC-fsl_ssi-Clean-up-coding-style-level/20171216-032026' into devel-spot-201712161301 >> git bisect bad c00658c095dd5d0a48ebdedd68de9c8c49ab0633 # 16:19 B 0 5 18 0 Merge 'linux-review/Christian-K-nig/MAINTAINERS-add-separate-entry-for-DRM-TTM/20171216-090756' into devel-spot-201712161301 >> git bisect bad 27c51a58b3376c4b5ea0481ed35a3f8f112e5294 # 16:38 B 0 1 14 0 Merge 'snitzer/dm-4.16-nvme_bio' into devel-spot-201712161301 >> git bisect bad 57a3119eb5ea6842e970be28ee659b7d2aa9d432 # 16:54 B 0 8 21 0 Merge 'linux-review/Daniel-Vetter/drm-rework-delayed-connector-cleanup-in-connector_iter/20171216-120456' into devel-spot-201712161301 >> git bisect good de03d6e01cc2c1cb142daf6cb5ee9f72314c4c8b # 17:15 G 11 0 11 11 0day base guard for 'devel-spot-201712161301' >> git bisect bad 995d11c4c0f1aa99d0f97fb747a4e0d04121cde2 # 17:27 B 0 4 17 0 drm: rework delayed connector cleanup in connector_iter >> # first bad commit: [995d11c4c0f1aa99d0f97fb747a4e0d04121cde2] drm: rework delayed connector cleanup in connector_iter >> git bisect good 50c4c4e268a2d7a3e58ebb698ac74da0de40ae36 # 17:36 G 33 0 32 80 Linux 4.15-rc3 >> # extra tests with debug options >> git bisect bad 995d11c4c0f1aa99d0f97fb747a4e0d04121cde2 # 17:47 B 0 3 16 0 drm: rework delayed connector cleanup in connector_iter >> # extra tests on HEAD of linux-devel/devel-spot-201712161301 >> git bisect bad 8174afd657ed57f8ea96940235a2f5a5fec10847 # 17:52 B 0 37 53 0 0day head guard for 'devel-spot-201712161301' >> # extra tests on tree/branch linux-review/Daniel-Vetter/drm-rework-delayed-connector-cleanup-in-connector_iter/20171216-120456 >> git bisect bad 995d11c4c0f1aa99d0f97fb747a4e0d04121cde2 # 18:09 B 0 15 28 0 drm: rework delayed connector cleanup in connector_iter >> # extra tests with first bad commit reverted >> git bisect good 14abeded1e578b748e38967e176ec5c97563c45a # 18:41 G 11 0 11 11 Revert "drm: rework delayed connector cleanup in connector_iter" >> >> --- >> 0-DAY kernel test infrastructure Open Source Technology Center >> https://lists.01.org/pipermail/lkp Intel Corporation > >