Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751740AbdGZKm7 (ORCPT ); Wed, 26 Jul 2017 06:42:59 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:47544 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750982AbdGZKm5 (ORCPT ); Wed, 26 Jul 2017 06:42:57 -0400 Date: Wed, 26 Jul 2017 12:42:49 +0200 (CEST) From: Thomas Gleixner To: Artem Savkov cc: Joerg Roedel , iommu@lists.linux-foundation.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: amd-iommu/x2apic: sleeping function called from invalid context In-Reply-To: <20170725135618.hev4vj7w24gm3a5q@shodan.usersys.redhat.com> Message-ID: References: <20170725135618.hev4vj7w24gm3a5q@shodan.usersys.redhat.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1509 Lines: 51 On Tue, 25 Jul 2017, Artem Savkov wrote: > Hi, > > Commit 1c3c5ea "sched/core: Enable might_sleep() and smp_processor_id() > checks early" seem to have uncovered an issue with amd-iommu/x2apic. > > Starting with that commit the following warning started to show up on AMD > systems during boot: > [ 0.160000] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747 > [ 0.160000] mutex_lock_nested+0x1b/0x20 > [ 0.160000] register_syscore_ops+0x1d/0x70 > [ 0.160000] state_next+0x119/0x910 > [ 0.160000] iommu_go_to_state+0x29/0x30 > [ 0.160000] amd_iommu_enable+0x13/0x23 > [ 0.160000] irq_remapping_enable+0x1b/0x39 > [ 0.160000] enable_IR_x2apic+0x91/0x196 > [ 0.160000] default_setup_apic_routing+0x16/0x6e > [ 0.160000] native_smp_prepare_cpus+0x257/0x2d5 Yep, that's clearly stupid. The completely untested patch below should cure the issue. Thanks, tglx 8<--------------- --- a/drivers/iommu/amd_iommu_init.c +++ b/drivers/iommu/amd_iommu_init.c @@ -2440,7 +2440,6 @@ static int __init state_next(void) break; case IOMMU_ACPI_FINISHED: early_enable_iommus(); - register_syscore_ops(&amd_iommu_syscore_ops); x86_platform.iommu_shutdown = disable_iommus; init_state = IOMMU_ENABLED; break; @@ -2559,6 +2558,8 @@ static int __init amd_iommu_init(void) for_each_iommu(iommu) iommu_flush_all_caches(iommu); } + } else { + register_syscore_ops(&amd_iommu_syscore_ops); } return ret;