From patchwork Thu Dec 18 12:23:23 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Larsson X-Patchwork-Id: 422562 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 7C1941400F1 for ; Thu, 18 Dec 2014 23:24:30 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752482AbaLRMY3 (ORCPT ); Thu, 18 Dec 2014 07:24:29 -0500 Received: from vsp-unauthed01.binero.net ([195.74.38.225]:28413 "EHLO bin-vsp-out-01.atm.binero.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752297AbaLRMY2 (ORCPT ); Thu, 18 Dec 2014 07:24:28 -0500 X-Halon-ID: cfe93669-86b0-11e4-a1ae-005056917a89 Authorized-sender: andreas@gaisler.com Received: from localhost.localdomain (unknown [92.33.28.242]) by bin-vsp-out-01.atm.binero.net (Halon Mail Gateway) with ESMTPA; Thu, 18 Dec 2014 13:24:28 +0100 (CET) From: Andreas Larsson To: davem@davemloft.net Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, software@gaisler.com Subject: [PATCH] sparc32: destroy_context() and switch_mm() needs to disable interrupts. Date: Thu, 18 Dec 2014 13:23:23 +0100 Message-Id: <1418905403-11154-1-git-send-email-andreas@gaisler.com> X-Mailer: git-send-email 1.7.10.4 Sender: sparclinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: sparclinux@vger.kernel.org Load balancing can be triggered in the critical sections protected by srmmu_context_spinlock in destroy_context() and switch_mm() and can hang the cpu waiting for the rq lock of another cpu that in turn has called switch_mm hangning on srmmu_context_spinlock leading to deadlock. So, disable interrupt while taking srmmu_context_spinlock in destroy_context() and switch_mm() so we don't deadlock. See also commit 77b838fa1ef0 ("[SPARC64]: destroy_context() needs to disable interrupts.") Signed-off-by: Andreas Larsson --- arch/sparc/mm/srmmu.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c index be65f03..5cbc96d 100644 --- a/arch/sparc/mm/srmmu.c +++ b/arch/sparc/mm/srmmu.c @@ -460,10 +460,12 @@ static void __init sparc_context_init(int numctx) void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, struct task_struct *tsk) { + unsigned long flags; + if (mm->context == NO_CONTEXT) { - spin_lock(&srmmu_context_spinlock); + spin_lock_irqsave(&srmmu_context_spinlock, flags); alloc_context(old_mm, mm); - spin_unlock(&srmmu_context_spinlock); + spin_unlock_irqrestore(&srmmu_context_spinlock, flags); srmmu_ctxd_set(&srmmu_context_table[mm->context], mm->pgd); } @@ -986,14 +988,15 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm) void destroy_context(struct mm_struct *mm) { + unsigned long flags; if (mm->context != NO_CONTEXT) { flush_cache_mm(mm); srmmu_ctxd_set(&srmmu_context_table[mm->context], srmmu_swapper_pg_dir); flush_tlb_mm(mm); - spin_lock(&srmmu_context_spinlock); + spin_lock_irqsave(&srmmu_context_spinlock, flags); free_context(mm->context); - spin_unlock(&srmmu_context_spinlock); + spin_unlock_irqrestore(&srmmu_context_spinlock, flags); mm->context = NO_CONTEXT; } }