From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: [4.2-rc4] acpi|drm|i915: circular locking dependency: acpi_video_get_backlight_type Date: Fri, 14 Aug 2015 10:24:51 +0200 Message-ID: <55CDA5D3.9030606@redhat.com> References: <20150812192620.GN5176@intel.com> <55CCAACF.7040109@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <55CCAACF.7040109@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= , Sedat Dilek Cc: Daniel Vetter , intel-gfx , "Rafael J. Wysocki" , LKML , Linux ACPI , Dave Airlie , Linus Torvalds , Len Brown List-Id: linux-acpi@vger.kernel.org SGksCgpPbiAxMy0wOC0xNSAxNjozMywgSGFucyBkZSBHb2VkZSB3cm90ZToKPiBIaSwKPgo+IE9u IDEyLTA4LTE1IDIxOjI2LCBWaWxsZSBTeXJqw6Rsw6Qgd3JvdGU6Cj4+IE9uIE1vbiwgQXVnIDEw LCAyMDE1IGF0IDA4OjI5OjAwUE0gKzAyMDAsIFNlZGF0IERpbGVrIHdyb3RlOgo+Pj4gT24gU2F0 LCBBdWcgMSwgMjAxNSBhdCAyOjIzIFBNLCBTZWRhdCBEaWxlayA8c2VkYXQuZGlsZWtAZ21haWwu Y29tPiB3cm90ZToKPj4+PiBPbiBNb24sIEp1bCAyNywgMjAxNSBhdCAxMjozMyBBTSwgU2VkYXQg RGlsZWsgPHNlZGF0LmRpbGVrQGdtYWlsLmNvbT4gd3JvdGU6Cj4+Pj4+IEhpLAo+Pj4+Pgo+Pj4+ PiB0aGlzIG15IGZpcnN0IGJ1aWxkIG9mIGEgNC4yLXJjTiBMaW51eC1rZXJuZWwgYW5kIEkgc2Vl IHRoaXMuLi4KPj4+Pj4KPj4+Pgo+Pj4+IEp1c3QgRllJOgo+Pj4+Cj4+Pj4gSSBhbSAqbm90KiBz ZWVpbmcgdGhpcyB3aXRoIGRybS1pbnRlbC1uaWdodGx5IGZyb20gYmVsb3cgdXJsLgo+Pj4+Cj4+ Pj4gQWxzbywgSSBwbGFuIHRvIHRlc3QgTGludXggdjQuMi1yYzUuCj4+Pj4KPj4+Cj4+PiBbIEND IExpbnVzIF0KPj4+Cj4+PiBLbm9jayBLbm9jayBLbm9jay4KPj4+Cj4+PiBUaGlzIGlzc3VlIHN0 aWxsIHJlbWFpbnMgaGVyZSAod2l0aCBDT05GSUdfRFJNX0k5MTU9bSkuLi4KPj4+Cj4+PiBbICAg MTguMjY5NzkyXSA9PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT0KPj4+IFsgICAxOC4yNjk3OThdIFsgSU5GTzogcG9zc2libGUgY2lyY3VsYXIgbG9j a2luZyBkZXBlbmRlbmN5IGRldGVjdGVkIF0KPj4+IFsgICAxOC4yNjk4MDVdIDQuMi4wLXJjNi0x LWluaXphLXNtYWxsICMxIE5vdCB0YWludGVkCj4+PiBbICAgMTguMjY5ODEwXSAtLS0tLS0tLS0t LS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tCj4+PiBbICAgMTgu MjY5ODE2XSBtb2Rwcm9iZS83MjcgaXMgdHJ5aW5nIHRvIGFjcXVpcmUgbG9jazoKPj4+IFsgICAx OC4yNjk4MjJdICAoaW5pdF9tdXRleCl7Ky4rLisufSwgYXQ6IFs8ZmZmZmZmZmZhMDA5MGYyZD5d Cj4+PiBhY3BpX3ZpZGVvX2dldF9iYWNrbGlnaHRfdHlwZSsweDE3LzB4MTY0IFt2aWRlb10KPj4+ IFsgICAxOC4yNjk4NDBdCj4+PiBbICAgMTguMjY5ODQwXSBidXQgdGFzayBpcyBhbHJlYWR5IGhv bGRpbmcgbG9jazoKPj4+IFsgICAxOC4yNjk4NDhdICAoJigmYmFja2xpZ2h0X25vdGlmaWVyKS0+ cndzZW0peysrKysuLn0sIGF0Ogo+Pj4gWzxmZmZmZmZmZjgxMGE2NTE5Pl0gX19ibG9ja2luZ19u b3RpZmllcl9jYWxsX2NoYWluKzB4MzkvMHg3MAo+Pj4gWyAgIDE4LjI2OTg2NF0KPj4+IFsgICAx OC4yNjk4NjRdIHdoaWNoIGxvY2sgYWxyZWFkeSBkZXBlbmRzIG9uIHRoZSBuZXcgbG9jay4KPj4+ IFsgICAxOC4yNjk4NjRdCj4+PiBbICAgMTguMjY5ODc1XQo+Pj4gWyAgIDE4LjI2OTg3NV0gdGhl IGV4aXN0aW5nIGRlcGVuZGVuY3kgY2hhaW4gKGluIHJldmVyc2Ugb3JkZXIpIGlzOgo+Pj4gWyAg IDE4LjI2OTg4NF0KPj4+IC4uLgo+Pj4KPj4+IEZ1bGwgZG1lc2cgbG9nIGFuZCBrZXJuZWwtY29u ZmlnIGF0dGFjaGVkLgo+Pj4KPj4+IFNoYWxsIEkgYWRkIFJ1c3R5IGFuZCBtb2R1bGVzL21vZHBy b2JlIGZvbGtzPwo+Pgo+PiBKdXN0IGdvdCBiYWNrIGZyb20gdmFjYXRpb24gYW5kIHdhcyBncmVl dGVkIGJ5IHRoaXMgc2FtZSBsb2NrZGVwIHNwbGF0Lgo+Pgo+PiBPbiBhIGh1bmNoIEkgcmV2ZXJ0 ZWQKPj4KPj4gY29tbWl0IDkzYTI5MWRmYWY5YzMyOGNhNWE5Y2VhMTczM2FmMWExMjhlZmU4OTAK Pj4gQXV0aG9yOiBIYW5zIGRlIEdvZWRlIDxoZGVnb2VkZUByZWRoYXQuY29tPgo+PiBEYXRlOiAg IFR1ZSBKdW4gMTYgMTY6Mjc6NTIgMjAxNSArMDIwMAo+Pgo+PiAgICAgIEFDUEkgLyB2aWRlbzog TW92ZSBiYWNrbGlnaHQgbm90aWZpZXIgdG8gdmlkZW9fZGV0ZWN0LmMKPj4KPj4gYW5kIHRoZSBw cm9ibGVtIHNlZW1zIHRvIGJlIGdvbmUuIEhhbnMsIGFueSB0aG91Z2h0cz8KPgo+IExvb2tpbmcg aW50byB0aGlzIGF0bSwgbG9ja2RlcCBjbGVhcmx5IGlzIHJpZ2h0Lgo+Cj4gU29ycnkgYWJvdXQg dGhpcyBJIGhhdmUgcHV0IGEgbG90IG9mIHRoaW5raW5nIGludG8gYXZvaWRpbmcKPiB0aGVzZSBr aW5kIG9mIGlzc3VlcyB3aXRoIHRoaXMgcGF0Y2gtc2V0LCBidXQgSSBkaWQgbm90IHJlYWxpemUK PiB0aGVyZSB3YXMgYW5vdGhlciBsb2NrICJoaWRpbmciIGluc2lkZSB0aGUgbm90aWZpZXItY2hh aW4uCj4KPiBGdXJ0aGVyIGFuYWx5c2lzIHNob3dzIHRoYXQgdGhlIGxvY2sgaW5zaWRlIHRoZSBu b3RpZmllci1jaGFpbgo+IGNhdXNlcyBzaW1pbGFyIHByb2JsZW1zIHZzIHJlZ2lzdGVyX2NvdW50 X211dGV4IGZyb20KPiBkcml2ZXJzL2FjcGkvYWNwaV92aWRlby5jLiBJJ20gd29ya2luZyBvbiBh IGZpeCBmb3IgdGhpcwo+IGF0bS4KCkhlaCwgbG9vayBhdCB3aGF0IEkganVzdCBmb3VuZCAoSSdt IHNoaWZ0aW5nIG15IHdvcmsgZm9jdXMKaW4gdGhlIGRpcmVjdGlvbiBvZiBub3V2ZWF1KSA6Cgpo dHRwczovL2J1Z3ppbGxhLnJlZGhhdC5jb20vc2hvd19idWcuY2dpP2lkPTExNTI4NzYKClNvIGl0 IGxvb2tzIGxpa2Ugd2UgaGF2ZSBoYWQgdGhlIHJvb3QgY2F1c2Ugb2YgdGhpcyBpc3N1ZQpmb3Ig YSBsb25nIHRpbWUgYWxyZWFkeSwgbWF5YmUgbXkgcmVjZW50IGJhY2tsaWdodCBzZWxlY3Rpb24K bG9naWMgY2xlYW51cCAvIHJld29yayBoYXMgbWFkZSBpdCBlYXNpZXIgdG8gdHJpZ2dlciB0aGUK bG9ja2RlcCB3YXJuaW5nIGZvciB0aGlzIHRob3VnaC4KCkFueWhvdyBhc3N1bWluZyBwZW9wbGUg YXJlIG9rIHdpdGggdGhlIGZpeCBJIHN1Ym1pdHRlZAp5ZXN0ZXJkYXkgd2UndmUgYSBmaXggZm9y IHRoaXMgbm93LgoKUmVnYXJkcywKCkhhbnMKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX18KSW50ZWwtZ2Z4IG1haWxpbmcgbGlzdApJbnRlbC1nZnhAbGlzdHMu ZnJlZWRlc2t0b3Aub3JnCmh0dHA6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0 aW5mby9pbnRlbC1nZngK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753783AbbHNIY7 (ORCPT ); Fri, 14 Aug 2015 04:24:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59737 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753218AbbHNIYz (ORCPT ); Fri, 14 Aug 2015 04:24:55 -0400 Subject: Re: [Intel-gfx] [4.2-rc4] acpi|drm|i915: circular locking dependency: acpi_video_get_backlight_type To: =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= , Sedat Dilek References: <20150812192620.GN5176@intel.com> <55CCAACF.7040109@redhat.com> Cc: Daniel Vetter , Dave Airlie , "Rafael J. Wysocki" , Len Brown , Linux ACPI , intel-gfx , Linus Torvalds , LKML From: Hans de Goede Message-ID: <55CDA5D3.9030606@redhat.com> Date: Fri, 14 Aug 2015 10:24:51 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <55CCAACF.7040109@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 13-08-15 16:33, Hans de Goede wrote: > Hi, > > On 12-08-15 21:26, Ville Syrjälä wrote: >> On Mon, Aug 10, 2015 at 08:29:00PM +0200, Sedat Dilek wrote: >>> On Sat, Aug 1, 2015 at 2:23 PM, Sedat Dilek wrote: >>>> On Mon, Jul 27, 2015 at 12:33 AM, Sedat Dilek wrote: >>>>> Hi, >>>>> >>>>> this my first build of a 4.2-rcN Linux-kernel and I see this... >>>>> >>>> >>>> Just FYI: >>>> >>>> I am *not* seeing this with drm-intel-nightly from below url. >>>> >>>> Also, I plan to test Linux v4.2-rc5. >>>> >>> >>> [ CC Linus ] >>> >>> Knock Knock Knock. >>> >>> This issue still remains here (with CONFIG_DRM_I915=m)... >>> >>> [ 18.269792] ====================================================== >>> [ 18.269798] [ INFO: possible circular locking dependency detected ] >>> [ 18.269805] 4.2.0-rc6-1-iniza-small #1 Not tainted >>> [ 18.269810] ------------------------------------------------------- >>> [ 18.269816] modprobe/727 is trying to acquire lock: >>> [ 18.269822] (init_mutex){+.+.+.}, at: [] >>> acpi_video_get_backlight_type+0x17/0x164 [video] >>> [ 18.269840] >>> [ 18.269840] but task is already holding lock: >>> [ 18.269848] (&(&backlight_notifier)->rwsem){++++..}, at: >>> [] __blocking_notifier_call_chain+0x39/0x70 >>> [ 18.269864] >>> [ 18.269864] which lock already depends on the new lock. >>> [ 18.269864] >>> [ 18.269875] >>> [ 18.269875] the existing dependency chain (in reverse order) is: >>> [ 18.269884] >>> ... >>> >>> Full dmesg log and kernel-config attached. >>> >>> Shall I add Rusty and modules/modprobe folks? >> >> Just got back from vacation and was greeted by this same lockdep splat. >> >> On a hunch I reverted >> >> commit 93a291dfaf9c328ca5a9cea1733af1a128efe890 >> Author: Hans de Goede >> Date: Tue Jun 16 16:27:52 2015 +0200 >> >> ACPI / video: Move backlight notifier to video_detect.c >> >> and the problem seems to be gone. Hans, any thoughts? > > Looking into this atm, lockdep clearly is right. > > Sorry about this I have put a lot of thinking into avoiding > these kind of issues with this patch-set, but I did not realize > there was another lock "hiding" inside the notifier-chain. > > Further analysis shows that the lock inside the notifier-chain > causes similar problems vs register_count_mutex from > drivers/acpi/acpi_video.c. I'm working on a fix for this > atm. Heh, look at what I just found (I'm shifting my work focus in the direction of nouveau) : https://bugzilla.redhat.com/show_bug.cgi?id=1152876 So it looks like we have had the root cause of this issue for a long time already, maybe my recent backlight selection logic cleanup / rework has made it easier to trigger the lockdep warning for this though. Anyhow assuming people are ok with the fix I submitted yesterday we've a fix for this now. Regards, Hans