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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2CDDAC05027 for ; Fri, 10 Feb 2023 17:44:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4K0WP+cecA9KKzOglBMusGvbJoGb0knOaRBMMnssH1c=; b=lgOziCBP3X9W69 R40NQ3j7zAJiDmVyeBXyrI4s3XP/m2xQeE5UE1seU28prl6y6g+KHPB7kqCn/6zv62GRq44xiNXIU t+p2NLCneiNVKB9J+s7TGlR0k8jM+iPnYbAls0vJmJecldw0gxp9oIsVCaPcAMEM/e8ouxX2DAvJr LrMvQUJmcROx8n7HJCHIj45bPLH1Ts3aDps8i93Y/pbNo6NYGqrkc2OSrmeUcwRPttIiDxXDcF6Cz 07Fpw3ScrJzxjROST0rcQniBw/3kHA7Dg2+ym9GDDCP/KWslR6s1uC6oxvYFIbGJY2n1aptAWijXI Eg4HiYvLCy2JxGCD2lLA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pQXQU-006l9E-Ej; Fri, 10 Feb 2023 17:43:10 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pQXQP-006l7u-V1 for linux-arm-kernel@lists.infradead.org; Fri, 10 Feb 2023 17:43:08 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 78DF72F4; Fri, 10 Feb 2023 09:43:43 -0800 (PST) Received: from [10.1.196.177] (eglon.cambridge.arm.com [10.1.196.177]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 183863F703; Fri, 10 Feb 2023 09:42:58 -0800 (PST) Message-ID: <5813b8c5-ae3e-87fd-fccc-94c9cd08816d@arm.com> Date: Fri, 10 Feb 2023 17:42:52 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [PATCH v2] firmware: arm_sdei: Fix sleep from invalid context BUG Content-Language: en-GB To: Pierre Gondois , linux-kernel@vger.kernel.org Cc: Will Deacon , Huacai Chen , John Garry , Shaokun Zhang , WANG Xuerui , Qi Liu , Bharat Bhushan , Huang Ying , Bibo Mao , "Jason A. Donenfeld" , Daniel Lezcano , linux-arm-kernel@lists.infradead.org References: <20221018130456.1356081-1-pierre.gondois@arm.com> From: James Morse In-Reply-To: <20221018130456.1356081-1-pierre.gondois@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230210_094306_140134_CECCC2C6 X-CRM114-Status: GOOD ( 22.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Pierre, Sorry its taken so long for me to catch up with this ... On 18/10/2022 14:04, Pierre Gondois wrote: > On an Ampere Altra, > Running a preemp_rt kernel based on v5.19-rc3-rt5 on an > Ampere Altra triggers: > [ 15.683141] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 > [ 15.683154] in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 24, name: cpuhp/0 > [ 15.683157] preempt_count: 0, expected: 0 > [ 15.683159] RCU nest depth: 0, expected: 0 > [ 15.683163] 3 locks held by cpuhp/0/24: > [ 15.683167] #0: ffffda30217c70d0 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x5c/0x248 > [ 15.683201] #1: ffffda30217c7120 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x5c/0x248 > [ 15.683205] #2: ffffda3021c711f0 (sdei_list_lock){....}-{3:3}, at: sdei_cpuhp_up+0x3c/0x130 > [ 15.683224] irq event stamp: 36 > [ 15.683226] hardirqs last enabled at (35): [] finish_task_switch+0xb4/0x2b0 > [ 15.683236] hardirqs last disabled at (36): [] cpuhp_thread_fun+0x21c/0x248 > [ 15.683238] softirqs last enabled at (0): [] copy_process+0x63c/0x1ac0 > [ 15.683245] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 15.683258] CPU: 0 PID: 24 Comm: cpuhp/0 Not tainted 5.19.0-rc3-rt5-[...] > [ 15.683265] Hardware name: WIWYNN Mt.Jade Server System B81.03001.0005/Mt.Jade Motherboard, BIOS 1.08.20220218 (SCP: 1.08.20220218) 2022/02/18 > [ 15.683268] Call trace: > [ 15.683271] dump_backtrace+0x114/0x120 > [ 15.683277] show_stack+0x20/0x70 > [ 15.683279] dump_stack_lvl+0x9c/0xd8 > [ 15.683288] dump_stack+0x18/0x34 > [ 15.683289] __might_resched+0x188/0x228 > [ 15.683292] rt_spin_lock+0x70/0x120 > [ 15.683301] sdei_cpuhp_up+0x3c/0x130 > [ 15.683303] cpuhp_invoke_callback+0x250/0xf08 > [ 15.683305] cpuhp_thread_fun+0x120/0x248 > [ 15.683308] smpboot_thread_fn+0x280/0x320 > [ 15.683315] kthread+0x130/0x140 > [ 15.683321] ret_from_fork+0x10/0x20 > sdei_cpuhp_up() is called in the STARTING hotplug section, > which runs whith interrupts disabled. Move CPUHP_AP_ARM_SDEI_ > state to the _ONLINE section to execute the cpuhp cb with > preemption enabled. The background to this is SDEI got its own cpuhp slot because 'perf NMI' support was one of the use-cases, but this got superseded by pNMI. Without an interaction with perf, the slot doesn't need to be that early. > Some SDEI calls (e.g. SDEI_1_0_FN_SDEI_PE_MASK) take actions on the > calling CPU. It is checked that preemption is disabled for them. > _ONLINE cpuhp cb are executed in the 'per CPU hotplug thread'. > Preemption is enabled in those threads, but their cpumask is limited > to 1 CPU. > Move 'WARN_ON_ONCE(preemptible())' statements so that SDEI cpuhp cb > don't trigger them. This means that no check will be done for some > cases, e.g. sdei_mask_local_cpu() invocations. (these things are documentation anyway) > Also add a check for the SDEI_1_0_FN_SDEI_PRIVATE_RESET SDEI call > which acts on the calling CPU. > diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c > index 1e1a51510e83..9b03e164a37a 100644 > --- a/drivers/firmware/arm_sdei.c > +++ b/drivers/firmware/arm_sdei.c > @@ -401,6 +399,8 @@ int sdei_event_enable(u32 event_num) > int err = -EINVAL; > struct sdei_event *event; > > + WARN_ON_ONCE(preemptible()); > + > mutex_lock(&sdei_events_lock); > event = sdei_event_find(event_num); > if (!event) { This doesn't look right. How can this code take a mutex if its in a non-preemptable context? > @@ -492,6 +490,7 @@ int sdei_event_unregister(u32 event_num) > struct sdei_event *event; > > WARN_ON(in_nmi()); > + WARN_ON_ONCE(preemptible()); > > mutex_lock(&sdei_events_lock); > event = sdei_event_find(event_num); Same again. > @@ -576,6 +573,7 @@ int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg) > struct sdei_event *event; > > WARN_ON(in_nmi()); > + WARN_ON_ONCE(preemptible()); > > mutex_lock(&sdei_events_lock); > if (sdei_event_find(event_num)) { Same again. I think you've copied these here because they called _local_event_unregister(), but they did that via on_each_cpu(), which is what made _local_event_unregister() non-preemtable. You can just remove these three, the original warnings were mostly documentation, and to catch myself out. (before RT moved the goal posts). With that: Reviewed-by: James Morse (could you trim the [timestamps] out of the commit log?) > @@ -765,7 +765,7 @@ static int sdei_device_freeze(struct device *dev) > int err; > > /* unregister private events */ > - cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING); > + cpuhp_remove_state(CPUHP_AP_ARM_SDEI_ONLINE); Is there any mileage in making this CPUHP_AP_ONLINE_DYN ? Perf really was the only reason that this needed to happen in any particular order. Thanks, James _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel