From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E383C3276E for ; Thu, 2 Jan 2020 22:54:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 34CF921D7D for ; Thu, 2 Jan 2020 22:54:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HecHc+53" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729391AbgABWyX (ORCPT ); Thu, 2 Jan 2020 17:54:23 -0500 Received: from mail-pl1-f194.google.com ([209.85.214.194]:44923 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728860AbgABWUo (ORCPT ); Thu, 2 Jan 2020 17:20:44 -0500 Received: by mail-pl1-f194.google.com with SMTP id az3so18321320plb.11; Thu, 02 Jan 2020 14:20:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=PLtzc8afBAuik4mTEPX+bPRzroMTmbjVIty4Kb/Ccyg=; b=HecHc+53rrATNHcWxXoP4AdeD8hyYVvdTMRETiWpv2WD1Ny5N0ajlLxrXFzNnGb1/U s3dcMUY5/itVgMI+PoD76k88we7rbq7/LVCJz5TEpnyultf7QlcZ9CRxAoot7GZVkI29 yBU9vM9Dkvar2MnFgdi8V+whDQpq0BFaPu9bXHlsRL78aWpQ/kDzW70R+r/ohF+mstQj 2sTB0WvgGMs+TL7q0/GTxeiwDPcZUfLn+UxwzU9qPCbrVs4XGlniYAQEmOrmsGRysgjf GnsGPbWmWmAx0mHxa0PJ/I3WhUBUdIviaqegKrjrtJAQ7Fer+FTHill8xjqjDtdHIdNv 1ZWA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=PLtzc8afBAuik4mTEPX+bPRzroMTmbjVIty4Kb/Ccyg=; b=NXEAM00JMZj8mxeA2RIphUxvmiW/8B2/GZQD4AN/Fq0hHJi8wQd3olQTtGIO+xtTb9 +/bcJsEwMt5smxd7uJUih0YZu3iMaIebNvb2UQzhh5IIUuBbrWu8C7mo+fcsTaOEL2VU y0sRgcBc5ti0xsfLyqle8r5znd93JB+hROeAx/b0TAD+rl1V/21PZvt2Z4SxTb+EUSTl /lAtkV2JJbD2UFFiEyt9F66RyrPyG8ArF5OoPHvEcRZREiGo0BEoLsd7+jbBQ1ba/MYZ /PjET3jL9+9T6Mngf6x8qMAEA7rWS+ENZTW1JQgDBYO0cQhRTJeYRzr2iQb0rlrh6mpm bZEQ== X-Gm-Message-State: APjAAAVtq2CXyhVWfk28Q25WO8QKQxJFd1sR531vatauRcuRctifTydC OaBglhZuT0hR5XHXRZ4X+sA6UvOX X-Google-Smtp-Source: APXvYqxl8JIMFlZaQYI4d/XNmoIWju3TnqNPgYwbee8KweSPW8fLd7oTHeHEVhiaD9ZRd4DQGU4dqw== X-Received: by 2002:a17:90a:8902:: with SMTP id u2mr22692997pjn.85.1578003643389; Thu, 02 Jan 2020 14:20:43 -0800 (PST) Received: from localhost ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id q8sm61808040pgg.92.2020.01.02.14.20.42 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 02 Jan 2020 14:20:42 -0800 (PST) Date: Thu, 2 Jan 2020 14:20:41 -0800 From: Guenter Roeck To: Sakari Ailus Cc: Petr Mladek , linux-kernel@vger.kernel.org, rafael@kernel.org, Andy Shevchenko , linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, Rob Herring , Heikki Krogerus , Joe Perches Subject: Re: [PATCH v9 09/12] lib/vsprintf: Make use of fwnode API to obtain node names and separators Message-ID: <20200102222041.GA29067@roeck-us.net> References: <20191003123219.11237-1-sakari.ailus@linux.intel.com> <20191003123219.11237-10-sakari.ailus@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191003123219.11237-10-sakari.ailus@linux.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, Oct 03, 2019 at 03:32:16PM +0300, Sakari Ailus wrote: > Instead of implementing our own means of discovering parent nodes, node > names or counting how many parents a node has, use the newly added > functions in the fwnode API to obtain that information. > > Signed-off-by: Sakari Ailus > Reviewed-by: Andy Shevchenko > Reviewed-by: Petr Mladek > --- This patch results in a lockdep splat when running one of my qemu emulations. See below for log and bisect results. A complete log is available at https://kerneltests.org/builders/qemu-arm-master/builds/1408/steps/qemubuildcommand/logs/stdio Guenter --- ====================================================== WARNING: possible circular locking dependency detected 5.5.0-rc4-00066-g738d2902773e #1 Not tainted ------------------------------------------------------ swapper/0/1 is trying to acquire lock: c1313b00 (logbuf_lock){-.-.}, at: vprintk_emit+0x68/0x2d4 but task is already holding lock: ef030b90 (&(&n->list_lock)->rlock){..-.}, at: free_debug_processing+0x38/0x418 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&(&n->list_lock)->rlock){..-.}: ___slab_alloc.constprop.23+0x12c/0x798 __slab_alloc.constprop.22+0x44/0x70 __kmalloc+0x384/0x41c of_populate_phandle_cache+0xcc/0x148 of_core_init+0x8/0xbc driver_init+0x1c/0x2c kernel_init_freeable+0xac/0x1b4 kernel_init+0x8/0x118 ret_from_fork+0x14/0x20 0x0 -> #1 (devtree_lock){....}: of_get_parent+0x18/0x34 of_fwnode_get_parent+0x34/0x40 fwnode_count_parents+0x28/0x58 fwnode_full_name_string+0x18/0xa0 device_node_string+0x490/0x4f0 pointer+0x440/0x4d8 vsnprintf+0x1bc/0x3d8 vscnprintf+0xc/0x24 vprintk_store+0x34/0x204 vprintk_emit+0x94/0x2d4 vprintk_default+0x20/0x28 printk+0x30/0x54 exynos4_pm_init_power_domain+0x220/0x258 do_one_initcall+0x8c/0x440 kernel_init_freeable+0x150/0x1b4 kernel_init+0x8/0x118 ret_from_fork+0x14/0x20 0x0 -> #0 (logbuf_lock){-.-.}: lock_acquire+0xec/0x290 _raw_spin_lock+0x38/0x48 vprintk_emit+0x68/0x2d4 vprintk_default+0x20/0x28 printk+0x30/0x54 unwind_frame+0x6a8/0x6fc walk_stackframe+0x2c/0x38 __save_stack_trace+0x84/0x8c stack_trace_save+0x3c/0x5c set_track+0x40/0x9c free_debug_processing+0x1a4/0x418 __slab_free+0x2d4/0x510 kmem_cache_free+0x44c/0x49c rcu_core+0x348/0x994 __do_softirq+0x164/0x668 irq_exit+0x16c/0x170 __handle_domain_irq+0x80/0xec gic_handle_irq+0x58/0x9c __irq_svc+0x70/0xb0 raid6_neon8_gen_syndrome_real+0x264/0x39c raid6_neon8_gen_syndrome_real+0x264/0x39c other info that might help us debug this: Chain exists of: logbuf_lock --> devtree_lock --> &(&n->list_lock)->rlock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&n->list_lock)->rlock); lock(devtree_lock); lock(&(&n->list_lock)->rlock); lock(logbuf_lock); *** DEADLOCK *** 2 locks held by swapper/0/1: #0: c131466c (rcu_callback){....}, at: rcu_core+0x304/0x994 #1: ef030b90 (&(&n->list_lock)->rlock){..-.}, at: free_debug_processing+0x38/0x418 stack backtrace: CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc4-00066-g738d2902773e #1 Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0xa4/0xd0) [] (dump_stack) from [] (check_noncircular+0x258/0x274) [] (check_noncircular) from [] (__lock_acquire+0x1870/0x2860) [] (__lock_acquire) from [] (lock_acquire+0xec/0x290) [] (lock_acquire) from [] (_raw_spin_lock+0x38/0x48) [] (_raw_spin_lock) from [] (vprintk_emit+0x68/0x2d4) [] (vprintk_emit) from [] (vprintk_default+0x20/0x28) [] (vprintk_default) from [] (printk+0x30/0x54) [] (printk) from [] (unwind_frame+0x6a8/0x6fc) [] (unwind_frame) from [] (walk_stackframe+0x2c/0x38) [] (walk_stackframe) from [] (__save_stack_trace+0x84/0x8c) [] (__save_stack_trace) from [] (stack_trace_save+0x3c/0x5c) [] (stack_trace_save) from [] (set_track+0x40/0x9c) [] (set_track) from [] (free_debug_processing+0x1a4/0x418) [] (free_debug_processing) from [] (__slab_free+0x2d4/0x510) [] (__slab_free) from [] (kmem_cache_free+0x44c/0x49c) [] (kmem_cache_free) from [] (rcu_core+0x348/0x994) [] (rcu_core) from [] (__do_softirq+0x164/0x668) [] (__do_softirq) from [] (irq_exit+0x16c/0x170) [] (irq_exit) from [] (__handle_domain_irq+0x80/0xec) [] (__handle_domain_irq) from [] (gic_handle_irq+0x58/0x9c) [] (gic_handle_irq) from [] (__irq_svc+0x70/0xb0) Exception stack(0xef19bd30 to 0xef19bd78) bd20: c0d43e50 c0d43e60 ef19bebc c0d43e70 bd40: c0d43e20 c0d43e10 00000400 00000430 00000440 00000450 00000460 00000470 bd60: c0d43e40 ef19bd80 c0d43e30 c0625c00 20000013 ffffffff [] (__irq_svc) from [] (raid6_neon8_gen_syndrome_real+0x264/0x39c) --- Bisect: # bad: [738d2902773e30939a982c8df7a7f94293659810] Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net # good: [219d54332a09e8d8741c1e1982f5eae56099de85] Linux 5.4 git bisect start 'HEAD' 'v5.4' # bad: [8c39f71ee2019e77ee14f88b1321b2348db51820] Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net git bisect bad 8c39f71ee2019e77ee14f88b1321b2348db51820 # good: [3b397c7ccafe0624018cb09fc96729f8f6165573] Merge tag 'regmap-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap git bisect good 3b397c7ccafe0624018cb09fc96729f8f6165573 # bad: [89d57dddd7d319ded00415790a0bb3c954b7e386] Merge tag 'media/v5.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media git bisect bad 89d57dddd7d319ded00415790a0bb3c954b7e386 # good: [9e7a03233e02afd3ee061e373355f34d7254f1e6] Merge tag 'pm-5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm git bisect good 9e7a03233e02afd3ee061e373355f34d7254f1e6 # good: [09578eacaaa44149738267083ccc050990409f86] Merge tag 'asoc-v5.5-2' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus git bisect good 09578eacaaa44149738267083ccc050990409f86 # good: [1c7ae4a51298d52a21f63b2214657982036c7498] media: ad5820: Add support for of-autoload git bisect good 1c7ae4a51298d52a21f63b2214657982036c7498 # good: [99cf8a7074c4ce3ff3685cd389f54e7bd4bbf510] media: dt-bindings: Fix building error for dt_binding_check git bisect good 99cf8a7074c4ce3ff3685cd389f54e7bd4bbf510 # good: [782b59711e1561ee0da06bc478ca5e8249aa8d09] Merge branch 'acpi-mm' git bisect good 782b59711e1561ee0da06bc478ca5e8249aa8d09 # good: [0ca40f41d795fd91811e44506bb73d0b9ca33bdd] Merge branch 'patchwork' into v4l_for_linus git bisect good 0ca40f41d795fd91811e44506bb73d0b9ca33bdd # bad: [a00351687f8a05773c1c57be80a5bbca68fa9ae8] software node: remove DEV_PROP_MAX git bisect bad a00351687f8a05773c1c57be80a5bbca68fa9ae8 # good: [9af7706492f985867d070861fe39fee0fe41326f] lib/vsprintf: Remove support for %pF and %pf in favour of %pS and %ps git bisect good 9af7706492f985867d070861fe39fee0fe41326f # bad: [83abc5a77f3b028b8c845c39ce4053119e1de35b] lib/vsprintf: OF nodes are first and foremost, struct device_nodes git bisect bad 83abc5a77f3b028b8c845c39ce4053119e1de35b # bad: [a92eb7621b9fb2c28a588ce333d226f56fab6a85] lib/vsprintf: Make use of fwnode API to obtain node names and separators git bisect bad a92eb7621b9fb2c28a588ce333d226f56fab6a85 # good: [1586c5ae2f9310235b5e70abe712c73fc32eb98f] lib/vsprintf: Add a note on re-using %pf or %pF git bisect good 1586c5ae2f9310235b5e70abe712c73fc32eb98f # first bad commit: [a92eb7621b9fb2c28a588ce333d226f56fab6a85] lib/vsprintf: Make use of fwnode API to obtain node names and separators