Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753641AbbBKTne (ORCPT ); Wed, 11 Feb 2015 14:43:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33744 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752642AbbBKTnc (ORCPT ); Wed, 11 Feb 2015 14:43:32 -0500 Date: Wed, 11 Feb 2015 14:43:19 -0500 From: Rik van Riel To: fweisbec@gmail.com Cc: paulmck@linux.vnet.ibm.com, luto@amacapital.net, will.deacon@arm.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mtosatti@redhat.com, borntraeger@de.ibm.com, lcapitulino@redhat.com, pbonzini@redhat.com Subject: [PATCH -v5 6/5] context_tracking: fix exception_enter when already in IN_KERNEL Message-ID: <20150211144319.2a0c29d6@cuia.bos.redhat.com> In-Reply-To: <1423600074-2907-1-git-send-email-riel@redhat.com> References: <1423600074-2907-1-git-send-email-riel@redhat.com> Organization: Red Hat, Inc MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1406 Lines: 39 If exception_enter happens when already in IN_KERNEL state, the code still calls context_tracking_exit, which ends up in rcu_eqs_exit_common, which explodes with a WARN_ON when it is called in a situation where dynticks are not enabled. This can be avoided by having exception_enter only switch to IN_KERNEL state if the current state is not already IN_KERNEL. Signed-off-by: Rik van Riel Reported-by: Luiz Capitulino --- Frederic, you will want this "bonus" patch, too :) Thanks to Luiz for finding this one. Whatever I was running did not trigger this issue... include/linux/context_tracking.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index b65fd1420e53..9da230406e8c 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -37,7 +37,8 @@ static inline enum ctx_state exception_enter(void) return 0; prev_ctx = this_cpu_read(context_tracking.state); - context_tracking_exit(prev_ctx); + if (prev_ctx != IN_KERNEL) + context_tracking_exit(prev_ctx); return prev_ctx; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/