From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757851AbcAKAoM (ORCPT ); Sun, 10 Jan 2016 19:44:12 -0500 Received: from mail-yk0-f177.google.com ([209.85.160.177]:35692 "EHLO mail-yk0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757563AbcAKAoJ (ORCPT ); Sun, 10 Jan 2016 19:44:09 -0500 From: l@dorileo.org To: Sebastian Andrzej Siewior Cc: LKML , Thomas Gleixner , rostedt@goodmis.org, John Kacur , linux-mm@kvack.org, Leandro Dorileo Subject: [RFC][4.1.15-rt17 PATCH] mm: swap: lru drain don't use workqueue with PREEMPT_RT_FULL Date: Sun, 10 Jan 2016 22:43:21 -0200 Message-Id: <1452473001-10518-1-git-send-email-l@dorileo.org> X-Mailer: git-send-email 2.7.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Leandro Dorileo Running a smp system with an -rt kernel, with CONFIG_PREEMPT_RT_FULL, in a heavy cpu load scenario and an arbitrary process tries to mlockall with MCL_CURRENT flag that process will block indefinitely - until the process resulting in the heavy cpu load finishes(the process's set the sched priority > 0). Since MCL_CURRENT flag is passed to mlockall it will try to drain the lru in all cpus. The lru_add_drain_all() will start an workqueue to drain lru on each online cpu and then try to flush the work(will wait until the work's finished). The drain for the heavy loaded core will never finished - like mentioned before - until the process resulting in the heavy cpu load finishes. The work will never be scheduled, even if the calling process has been so. This patch adds an lru_add_drain_all() implementation for such situation, and synchronously do the lru drain on behalf of the calling process. Signed-off-by: Leandro Dorileo --- mm/swap.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/mm/swap.c b/mm/swap.c index 1785ac6..df807b4 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -864,6 +864,23 @@ void lru_add_drain(void) local_unlock_cpu(swapvec_lock); } +#ifdef CONFIG_PREEMPT_RT_FULL +void lru_add_drain_all(void) +{ + static DEFINE_MUTEX(lock); + int cpu; + + mutex_lock(&lock); + get_online_cpus(); + + for_each_online_cpu(cpu) { + smp_call_function_single(cpu, lru_add_drain, NULL, 1); + } + + put_online_cpus(); + mutex_unlock(&lock); +} +#else static void lru_add_drain_per_cpu(struct work_struct *dummy) { lru_add_drain(); @@ -900,6 +917,7 @@ void lru_add_drain_all(void) put_online_cpus(); mutex_unlock(&lock); } +#endif /** * release_pages - batched page_cache_release() -- 2.7.0