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=-5.3 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 1935BC49ED9 for ; Wed, 11 Sep 2019 01:10:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 94CC22171F for ; Wed, 11 Sep 2019 01:10:17 +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="BSOQ/u91" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 94CC22171F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EB7696B0005; Tue, 10 Sep 2019 21:10:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E404F6B0006; Tue, 10 Sep 2019 21:10:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CDFD56B0007; Tue, 10 Sep 2019 21:10:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 9F5C36B0005 for ; Tue, 10 Sep 2019 21:10:16 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 309B98243768 for ; Wed, 11 Sep 2019 01:10:16 +0000 (UTC) X-FDA: 75920858832.03.line87_1f5d743ccd33d X-HE-Tag: line87_1f5d743ccd33d X-Filterd-Recvd-Size: 14303 Received: from mail-pf1-f193.google.com (mail-pf1-f193.google.com [209.85.210.193]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Wed, 11 Sep 2019 01:10:15 +0000 (UTC) Received: by mail-pf1-f193.google.com with SMTP id r12so12610153pfh.1 for ; Tue, 10 Sep 2019 18:10:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=ESLG1t6IreprN3RkgGIaM4Lu+h+CB2JumPRW4tm4Exo=; b=BSOQ/u91jh54LUC0H1dXoOioyZkLhI20WMwYU2psrg8kKoICo0yeyNZyUQt6rzjder DipA0Pg2A0n9OMtpze6Iuf2EXLxwwPAxzBHc6MK2ubUgpdJ8N2T/KL6OQS7oGo0nKEy4 BJObBC13qHFF0k4ppmrhI4ddOoH7EWEqUCJsAjbBIIsqwTYUKmt8FUX81k3+BvdidUei TLudA2g58dKcRnmHgId+CbRermXt7kE9UXEbVSXAI5wsxuyM9gZKCholmo3aTNzv54U2 zGJlb9gnd8LflECwAmHPd+MytLqNZWxjoRHGlUjYKhD4twp2tedKM5Rsytg7d/qFeiu3 sGYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=ESLG1t6IreprN3RkgGIaM4Lu+h+CB2JumPRW4tm4Exo=; b=rD68a9DSaQXj9sSFKGvA/7d0vcpcCoeUU/h1+Ie7vgW03x7diSToYZxIBkJ8BEMkAw Gd0bnHnbYkOsQCIaRhAVRho+QVlxbEcO1LooAxsFDrUniBVoBOaykic/8qN6QO6T1Z2Q sNydV+WDjiyVIpCREbtcbxGoLU85EeBWQne2K9CP3XI58aYHq6SGrL+JGGgXg1YUifo5 eWzVpZR9AQVi9qhK20ZU4bQxKvAwhHFnyb6Tk/Nnbtwh4n9X/CVOsPpqnFJhh1/zvsqU UJuxmJnLE4tHHMHQ66OupiZ0x0JF4KwucG5eq1HZB74/cnCEnFCuQE9nmL5RtN9LwHsJ tFDg== X-Gm-Message-State: APjAAAUKKGAgLbjbDHxID8x0A1GnKVXC5CRWQLSCWPZ9aOB3EPTEPpW0 iRFXBLdSp6fAt6F9bOSTXAY= X-Google-Smtp-Source: APXvYqzMlNjnumil4089/9G8uPqoaC1MxhFNFaUHMsfqpe5cc4iNVywNJfCAkgwHYwb8enPKrEh0Gg== X-Received: by 2002:a62:5ac1:: with SMTP id o184mr38187912pfb.67.1568164214174; Tue, 10 Sep 2019 18:10:14 -0700 (PDT) Received: from localhost ([110.70.15.70]) by smtp.gmail.com with ESMTPSA id u16sm18945653pgm.83.2019.09.10.18.10.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Sep 2019 18:10:13 -0700 (PDT) Date: Wed, 11 Sep 2019 10:10:08 +0900 From: Sergey Senozhatsky To: Qian Cai Cc: Petr Mladek , Steven Rostedt , Catalin Marinas , Will Deacon , Sergey Senozhatsky , Dan Williams , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Peter Zijlstra , Waiman Long , Thomas Gleixner , Theodore Ts'o , Arnd Bergmann , Greg Kroah-Hartman Subject: Re: page_alloc.shuffle=1 + CONFIG_PROVE_LOCKING=y = arm64 hang Message-ID: <20190911011008.GA4420@jagdpanzerIV> References: <1566509603.5576.10.camel@lca.pw> <1567717680.5576.104.camel@lca.pw> <1568128954.5576.129.camel@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1568128954.5576.129.camel@lca.pw> User-Agent: Mutt/1.12.1 (2019-06-15) Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Cc-ing Ted, Arnd, Greg On (09/10/19 11:22), Qian Cai wrote: > [ 1078.283869][T43784] -> #3 (&(&port->lock)->rlock){-.-.}: > [ 1078.291350][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__lock_acquire+0x5c8/0xbb= 0 > [ 1078.296394][T43784]=A0=A0=A0=A0=A0=A0=A0=A0lock_acquire+0x154/0x428 > [ 1078.301266][T43784]=A0=A0=A0=A0=A0=A0=A0=A0_raw_spin_lock_irqsave+0x= 80/0xa0 > [ 1078.306831][T43784]=A0=A0=A0=A0=A0=A0=A0=A0tty_port_tty_get+0x28/0x6= 8 > [ 1078.311873][T43784]=A0=A0=A0=A0=A0=A0=A0=A0tty_port_default_wakeup+0= x20/0x40 > [ 1078.317523][T43784]=A0=A0=A0=A0=A0=A0=A0=A0tty_port_tty_wakeup+0x38/= 0x48 > [ 1078.322827][T43784]=A0=A0=A0=A0=A0=A0=A0=A0uart_write_wakeup+0x2c/0x= 50 > [ 1078.327956][T43784]=A0=A0=A0=A0=A0=A0=A0=A0pl011_tx_chars+0x240/0x26= 0 > [ 1078.332999][T43784]=A0=A0=A0=A0=A0=A0=A0=A0pl011_start_tx+0x24/0xa8 > [ 1078.337868][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__uart_start+0x90/0xa0 > [ 1078.342563][T43784]=A0=A0=A0=A0=A0=A0=A0=A0uart_write+0x15c/0x2c8 > [ 1078.347261][T43784]=A0=A0=A0=A0=A0=A0=A0=A0do_output_char+0x1c8/0x2b= 0 > [ 1078.352304][T43784]=A0=A0=A0=A0=A0=A0=A0=A0n_tty_write+0x300/0x668 > [ 1078.357087][T43784]=A0=A0=A0=A0=A0=A0=A0=A0tty_write+0x2e8/0x430 > [ 1078.361696][T43784]=A0=A0=A0=A0=A0=A0=A0=A0redirected_tty_write+0xcc= /0xe8 > [ 1078.367086][T43784]=A0=A0=A0=A0=A0=A0=A0=A0do_iter_write+0x228/0x270 > [ 1078.372041][T43784]=A0=A0=A0=A0=A0=A0=A0=A0vfs_writev+0x10c/0x1c8 > [ 1078.376735][T43784]=A0=A0=A0=A0=A0=A0=A0=A0do_writev+0xdc/0x180 > [ 1078.381257][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__arm64_sys_writev+0x50/0= x60 > [ 1078.386476][T43784]=A0=A0=A0=A0=A0=A0=A0=A0el0_svc_handler+0x11c/0x1= f0 > [ 1078.391606][T43784]=A0=A0=A0=A0=A0=A0=A0=A0el0_svc+0x8/0xc > [ 1078.395691][T43784]=A0 uart_port->lock -> tty_port->lock This thing along is already a bit suspicious. We re-enter tty here: tty -> uart -> serial -> tty And we re-enter tty under uart_port->lock. > [ 1078.395691][T43784] -> #2 (&port_lock_key){-.-.}: > [ 1078.402561][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__lock_acquire+0x5c8/0xbb= 0 > [ 1078.407604][T43784]=A0=A0=A0=A0=A0=A0=A0=A0lock_acquire+0x154/0x428 > [ 1078.412474][T43784]=A0=A0=A0=A0=A0=A0=A0=A0_raw_spin_lock+0x68/0x88 > [ 1078.417343][T43784]=A0=A0=A0=A0=A0=A0=A0=A0pl011_console_write+0x2ac= /0x318 > [ 1078.422820][T43784]=A0=A0=A0=A0=A0=A0=A0=A0console_unlock+0x3c4/0x89= 8 > [ 1078.427863][T43784]=A0=A0=A0=A0=A0=A0=A0=A0vprintk_emit+0x2d4/0x460 > [ 1078.432732][T43784]=A0=A0=A0=A0=A0=A0=A0=A0vprintk_default+0x48/0x58 > [ 1078.437688][T43784]=A0=A0=A0=A0=A0=A0=A0=A0vprintk_func+0x194/0x250 > [ 1078.442557][T43784]=A0=A0=A0=A0=A0=A0=A0=A0printk+0xbc/0xec > [ 1078.446732][T43784]=A0=A0=A0=A0=A0=A0=A0=A0register_console+0x4a8/0x= 580 > [ 1078.451947][T43784]=A0=A0=A0=A0=A0=A0=A0=A0uart_add_one_port+0x748/0= x878 > [ 1078.457250][T43784]=A0=A0=A0=A0=A0=A0=A0=A0pl011_register_port+0x98/= 0x128 > [ 1078.462639][T43784]=A0=A0=A0=A0=A0=A0=A0=A0sbsa_uart_probe+0x398/0x4= 80 > [ 1078.467772][T43784]=A0=A0=A0=A0=A0=A0=A0=A0platform_drv_probe+0x70/0= x108 > [ 1078.473075][T43784]=A0=A0=A0=A0=A0=A0=A0=A0really_probe+0x15c/0x5d8 > [ 1078.477944][T43784]=A0=A0=A0=A0=A0=A0=A0=A0driver_probe_device+0x94/= 0x1d0 > [ 1078.483335][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__device_attach_driver+0x= 11c/0x1a8 > [ 1078.489072][T43784]=A0=A0=A0=A0=A0=A0=A0=A0bus_for_each_drv+0xf8/0x1= 58 > [ 1078.494201][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__device_attach+0x164/0x2= 40 > [ 1078.499331][T43784]=A0=A0=A0=A0=A0=A0=A0=A0device_initial_probe+0x24= /0x30 > [ 1078.504721][T43784]=A0=A0=A0=A0=A0=A0=A0=A0bus_probe_device+0xf0/0x1= 00 > [ 1078.509850][T43784]=A0=A0=A0=A0=A0=A0=A0=A0device_add+0x63c/0x960 > [ 1078.514546][T43784]=A0=A0=A0=A0=A0=A0=A0=A0platform_device_add+0x1ac= /0x3b8 > [ 1078.520023][T43784]=A0=A0=A0=A0=A0=A0=A0=A0platform_device_register_= full+0x1fc/0x290 > [ 1078.526373][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_create_platform_devi= ce.part.0+0x264/0x3a8 > [ 1078.533152][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_create_platform_devi= ce+0x68/0x80 > [ 1078.539150][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_default_enumeration+= 0x34/0x78 > [ 1078.544887][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_bus_attach+0x340/0x3= b8 > [ 1078.550015][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_bus_attach+0xf8/0x3b= 8 > [ 1078.555057][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_bus_attach+0xf8/0x3b= 8 > [ 1078.560099][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_bus_attach+0xf8/0x3b= 8 > [ 1078.565142][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_bus_scan+0x9c/0x100 > [ 1078.570015][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_scan_init+0x16c/0x32= 0 > [ 1078.575058][T43784]=A0=A0=A0=A0=A0=A0=A0=A0acpi_init+0x330/0x3b8 > [ 1078.579666][T43784]=A0=A0=A0=A0=A0=A0=A0=A0do_one_initcall+0x158/0x7= ec > [ 1078.584797][T43784]=A0=A0=A0=A0=A0=A0=A0=A0kernel_init_freeable+0x9a= 8/0xa70 > [ 1078.590360][T43784]=A0=A0=A0=A0=A0=A0=A0=A0kernel_init+0x18/0x138 > [ 1078.595055][T43784]=A0=A0=A0=A0=A0=A0=A0=A0ret_from_fork+0x10/0x1c > > [ 1078.599835][T43784] -> #1 (console_owner){-...}: > [ 1078.606618][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__lock_acquire+0x5c8/0xbb= 0 > [ 1078.611661][T43784]=A0=A0=A0=A0=A0=A0=A0=A0lock_acquire+0x154/0x428 > [ 1078.616530][T43784]=A0=A0=A0=A0=A0=A0=A0=A0console_unlock+0x298/0x89= 8 > [ 1078.621573][T43784]=A0=A0=A0=A0=A0=A0=A0=A0vprintk_emit+0x2d4/0x460 > [ 1078.626442][T43784]=A0=A0=A0=A0=A0=A0=A0=A0vprintk_default+0x48/0x58 > [ 1078.631398][T43784]=A0=A0=A0=A0=A0=A0=A0=A0vprintk_func+0x194/0x250 > [ 1078.636267][T43784]=A0=A0=A0=A0=A0=A0=A0=A0printk+0xbc/0xec > [ 1078.640443][T43784]=A0=A0=A0=A0=A0=A0=A0=A0_warn_unseeded_randomness= +0xb4/0xd0 > [ 1078.646267][T43784]=A0=A0=A0=A0=A0=A0=A0=A0get_random_u64+0x4c/0x100 > [ 1078.651224][T43784]=A0=A0=A0=A0=A0=A0=A0=A0add_to_free_area_random+0= x168/0x1a0 > [ 1078.657047][T43784]=A0=A0=A0=A0=A0=A0=A0=A0free_one_page+0x3dc/0xd08 > [ 1078.662003][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__free_pages_ok+0x490/0xd= 00 > [ 1078.667132][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__free_pages+0xc4/0x118 > [ 1078.671914][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__free_pages_core+0x2e8/0= x428 > [ 1078.677219][T43784]=A0=A0=A0=A0=A0=A0=A0=A0memblock_free_pages+0xa4/= 0xec > [ 1078.682522][T43784]=A0=A0=A0=A0=A0=A0=A0=A0memblock_free_all+0x264/0= x330 > [ 1078.687825][T43784]=A0=A0=A0=A0=A0=A0=A0=A0mem_init+0x90/0x148 > [ 1078.692259][T43784]=A0=A0=A0=A0=A0=A0=A0=A0start_kernel+0x368/0x684 zone->lock --> uart_port->lock Some debugging options/warnings/error print outs/etc introduce deadlock patterns. This adds zone->lock --> uart_port->lock, which then brings in uart_port->lock --> tty_port->lock, which in turn brings tty_port->lock --> zone->lock. > [ 1078.697126][T43784] -> #0 (&(&zone->lock)->rlock){-.-.}: > [ 1078.704604][T43784]=A0=A0=A0=A0=A0=A0=A0=A0check_prev_add+0x120/0x11= 38 > [ 1078.709733][T43784]=A0=A0=A0=A0=A0=A0=A0=A0validate_chain+0x888/0x12= 70 > [ 1078.714863][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__lock_acquire+0x5c8/0xbb= 0 > [ 1078.719906][T43784]=A0=A0=A0=A0=A0=A0=A0=A0lock_acquire+0x154/0x428 > [ 1078.724776][T43784]=A0=A0=A0=A0=A0=A0=A0=A0_raw_spin_lock+0x68/0x88 > [ 1078.729645][T43784]=A0=A0=A0=A0=A0=A0=A0=A0rmqueue_bulk.constprop.21= +0xb0/0x1218 > [ 1078.735643][T43784]=A0=A0=A0=A0=A0=A0=A0=A0get_page_from_freelist+0x= 898/0x24a0 > [ 1078.741467][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__alloc_pages_nodemask+0x= 2a8/0x1d08 > [ 1078.747291][T43784]=A0=A0=A0=A0=A0=A0=A0=A0alloc_pages_current+0xb4/= 0x150 > [ 1078.752682][T43784]=A0=A0=A0=A0=A0=A0=A0=A0allocate_slab+0xab8/0x235= 0 > [ 1078.757725][T43784]=A0=A0=A0=A0=A0=A0=A0=A0new_slab+0x98/0xc0 > [ 1078.762073][T43784]=A0=A0=A0=A0=A0=A0=A0=A0___slab_alloc+0x66c/0xa30 > [ 1078.767029][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__slab_alloc+0x68/0xc8 > [ 1078.771725][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__kmalloc+0x3d4/0x658 > [ 1078.776333][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__tty_buffer_request_room= +0xd4/0x220 > [ 1078.782244][T43784]=A0=A0=A0=A0=A0=A0=A0=A0tty_insert_flip_string_fi= xed_flag+0x6c/0x128 > [ 1078.788849][T43784]=A0=A0=A0=A0=A0=A0=A0=A0pty_write+0x98/0x100 > [ 1078.793370][T43784]=A0=A0=A0=A0=A0=A0=A0=A0n_tty_write+0x2a0/0x668 > [ 1078.798152][T43784]=A0=A0=A0=A0=A0=A0=A0=A0tty_write+0x2e8/0x430 > [ 1078.802760][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__vfs_write+0x5c/0xb0 > [ 1078.807368][T43784]=A0=A0=A0=A0=A0=A0=A0=A0vfs_write+0xf0/0x230 > [ 1078.811890][T43784]=A0=A0=A0=A0=A0=A0=A0=A0ksys_write+0xd4/0x180 > [ 1078.816498][T43784]=A0=A0=A0=A0=A0=A0=A0=A0__arm64_sys_write+0x4c/0x= 60 > [ 1078.821627][T43784]=A0=A0=A0=A0=A0=A0=A0=A0el0_svc_handler+0x11c/0x1= f0 > [ 1078.826756][T43784]=A0=A0=A0=A0=A0=A0=A0=A0el0_svc+0x8/0xc tty_port->lock --> zone->lock > [ 1078.830842][T43784] other info that might help us debug this: > [ 1078.830842][T43784]=A0 > [ 1078.840918][T43784] Chain exists of: > [ 1078.840918][T43784]=A0=A0=A0&(&zone->lock)->rlock --> &port_lock_key= --> &(&port-> >lock)->rlock > [ 1078.840918][T43784]=A0 > [ 1078.854731][T43784]=A0=A0Possible unsafe locking scenario: > [ 1078.854731][T43784]=A0 > [ 1078.862029][T43784]=A0=A0=A0=A0=A0=A0=A0=A0CPU0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0CPU1 > [ 1078.867243][T43784]=A0=A0=A0=A0=A0=A0=A0=A0----=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0---- > [ 1078.872457][T43784]=A0=A0=A0lock(&(&port->lock)->rlock); > [ 1078.877238][T43784]=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0lock(&port_lock_key); > [ 1078.883929][T43784]=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0lock(&(&port->lock)->rlock); > [ 1078.891228][T43784]=A0=A0=A0lock(&(&zone->lock)->rlock); > [ 1078.896010][T43784]=A0 > [ 1078.896010][T43784]=A0=A0*** DEADLOCK *** [..] > [ 1078.980932][T43784]=A0=A0dump_backtrace+0x0/0x228 > [ 1078.985279][T43784]=A0=A0show_stack+0x24/0x30 > [ 1078.989282][T43784]=A0=A0dump_stack+0xe8/0x13c > [ 1078.993370][T43784]=A0=A0print_circular_bug+0x334/0x3d8 > [ 1078.998240][T43784]=A0=A0check_noncircular+0x268/0x310 > [ 1079.003022][T43784]=A0=A0check_prev_add+0x120/0x1138 > [ 1079.007631][T43784]=A0=A0validate_chain+0x888/0x1270 > [ 1079.012241][T43784]=A0=A0__lock_acquire+0x5c8/0xbb0 > [ 1079.016763][T43784]=A0=A0lock_acquire+0x154/0x428 > [ 1079.021111][T43784]=A0=A0_raw_spin_lock+0x68/0x88 > [ 1079.025460][T43784]=A0=A0rmqueue_bulk.constprop.21+0xb0/0x1218 > [ 1079.030937][T43784]=A0=A0get_page_from_freelist+0x898/0x24a0 > [ 1079.036240][T43784]=A0=A0__alloc_pages_nodemask+0x2a8/0x1d08 > [ 1079.041542][T43784]=A0=A0alloc_pages_current+0xb4/0x150 > [ 1079.046412][T43784]=A0=A0allocate_slab+0xab8/0x2350 > [ 1079.050934][T43784]=A0=A0new_slab+0x98/0xc0 > [ 1079.054761][T43784]=A0=A0___slab_alloc+0x66c/0xa30 > [ 1079.059196][T43784]=A0=A0__slab_alloc+0x68/0xc8 > [ 1079.063371][T43784]=A0=A0__kmalloc+0x3d4/0x658 > [ 1079.067458][T43784]=A0=A0__tty_buffer_request_room+0xd4/0x220 > [ 1079.072847][T43784]=A0=A0tty_insert_flip_string_fixed_flag+0x6c/0x12= 8 > [ 1079.078932][T43784]=A0=A0pty_write+0x98/0x100 > [ 1079.082932][T43784]=A0=A0n_tty_write+0x2a0/0x668 > [ 1079.087193][T43784]=A0=A0tty_write+0x2e8/0x430 > [ 1079.091280][T43784]=A0=A0__vfs_write+0x5c/0xb0 > [ 1079.095367][T43784]=A0=A0vfs_write+0xf0/0x230 > [ 1079.099368][T43784]=A0=A0ksys_write+0xd4/0x180 > [ 1079.103455][T43784]=A0=A0__arm64_sys_write+0x4c/0x60 > [ 1079.108064][T43784]=A0=A0el0_svc_handler+0x11c/0x1f0 > [ 1079.112672][T43784]=A0=A0el0_svc+0x8/0xc tty_port->lock --> zone->lock For instance, I don't really like the re-entrant tty, at least not under uart_port->lock. This, maybe, can be one of the solutions. Another one, a quick and dirty one, (and so many people will blame me for this) would be to break zone->{printk}->uart chain... Something like this --- drivers/char/random.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 9b54cdb301d3..975015857200 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1687,8 +1687,9 @@ static void _warn_unseeded_randomness(const char *f= unc_name, void *caller, print_once =3D true; #endif if (__ratelimit(&unseeded_warning)) - pr_notice("random: %s called from %pS with crng_init=3D%d\n", - func_name, caller, crng_init); + printk_deferred(KERN_NOTICE "random: %s called from %pS " + "with crng_init=3D%d\n", func_name, caller, + crng_init); } =20 /* @@ -2462,4 +2463,4 @@ void add_bootloader_randomness(const void *buf, uns= igned int size) else add_device_randomness(buf, size); } -EXPORT_SYMBOL_GPL(add_bootloader_randomness); \ No newline at end of file +EXPORT_SYMBOL_GPL(add_bootloader_randomness);