From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756226AbZKWQak (ORCPT ); Mon, 23 Nov 2009 11:30:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756441AbZKWQaB (ORCPT ); Mon, 23 Nov 2009 11:30:01 -0500 Received: from hera.kernel.org ([140.211.167.34]:52723 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756122AbZKWQ2W (ORCPT ); Mon, 23 Nov 2009 11:28:22 -0500 From: Tejun Heo To: peterz@infradead.org, torvalds@linux-foundation.org, awalls@radix.net, linux-kernel@vger.kernel.org, jeff@garzik.org, mingo@elte.hu, akpm@linux-foundation.org, jens.axboe@oracle.com, rusty@rustcorp.com.au, cl@linux-foundation.org, dhowells@redhat.com, arjan@linux.intel.com, avi@redhat.com, johannes@sipsolutions.net Cc: Tejun Heo Subject: [PATCH 01/14] sched, kvm: fix race condition involving sched_in_preempt_notifers Date: Tue, 24 Nov 2009 01:26:51 +0900 Message-Id: <1258993624-28735-2-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.6.5.3 In-Reply-To: <1258993624-28735-1-git-send-email-tj@kernel.org> References: <1258993624-28735-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In finish_task_switch(), fire_sched_in_preempt_notifiers() is called after finish_lock_switch(). However, depending on architecture, preemption can be enabled after finish_lock_switch() which breaks the semantics of preempt notifiers. Move it before finish_arch_switch(). This also makes in notifiers symmetric to out notifiers in terms of locking - now both are called under rq lock. Signed-off-by: Tejun Heo Cc: Avi Kivity --- kernel/sched.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 3c11ae0..de8a765 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2751,9 +2751,9 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev) prev_state = prev->state; finish_arch_switch(prev); perf_event_task_sched_in(current, cpu_of(rq)); + fire_sched_in_preempt_notifiers(current); finish_lock_switch(rq, prev); - fire_sched_in_preempt_notifiers(current); if (mm) mmdrop(mm); if (unlikely(prev_state == TASK_DEAD)) { -- 1.6.5.3