Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752029AbbERGqI (ORCPT ); Mon, 18 May 2015 02:46:08 -0400 Received: from mail-wg0-f47.google.com ([74.125.82.47]:36083 "EHLO mail-wg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751102AbbERGp6 (ORCPT ); Mon, 18 May 2015 02:45:58 -0400 Date: Mon, 18 May 2015 08:45:52 +0200 From: Ingo Molnar To: Gabriele Mazzotta Cc: juri.lelli@arm.com, mingo@redhat.com, peterz@infradead.org, linux-kernel@vger.kernel.org, len.brown@intel.com, andrey.semin@intel.com Subject: Re: Regression: turbostat stops working after suspend/resume cycle Message-ID: <20150518064552.GA12869@gmail.com> References: <3301457.KOfdo1KMTP@xps13> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3301457.KOfdo1KMTP@xps13> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4506 Lines: 149 * Gabriele Mazzotta wrote: > Hi, > > I've recently noticed that if I suspend and resume my laptop, I can no > longer execute turbostat. This is what I get when I try to start it: > # turbostat > Could not migrate to CPU 1 > turbostat: re-initialized with num_cpus 4 > Could not migrate to CPU 1 > > Since everything works as expected with v4.0, I ran a bisection and > found that commit 3c18d447b3b36a8d ("sched/core: Check for available > DL bandwidth in cpuset_cpu_inactive()") is the cause of the regression. > > I don't know if there's something else affected by that change, but > I can consistently reproduce the bug with turbostat. > > I can provide more info if needed. Does this commit: 533445c6e533 sched/core: Fix regression in cpuset_cpu_inactive() for suspend which is already in Linus's tree, and which should be part of -rc4, fix it? Also attached below. Thanks, Ingo ====================> >From 533445c6e53368569e50ab3fb712230c03d523f3 Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Mon, 4 May 2015 03:09:36 -0700 Subject: [PATCH] sched/core: Fix regression in cpuset_cpu_inactive() for suspend Commit 3c18d447b3b3 ("sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()"), a SCHED_DEADLINE bugfix, had a logic error that caused a regression in setting a CPU inactive during suspend. I ran into this when a program was failing pthread_setaffinity_np() with EINVAL after a suspend+wake up. A simple reproducer: $ ./a.out sched_setaffinity: Success $ systemctl suspend $ ./a.out sched_setaffinity: Invalid argument ... where ./a.out is: #define _GNU_SOURCE #include #include #include #include #include #include int main(void) { long num_cores; cpu_set_t cpu_set; int ret; num_cores = sysconf(_SC_NPROCESSORS_ONLN); CPU_ZERO(&cpu_set); CPU_SET(num_cores - 1, &cpu_set); errno = 0; ret = sched_setaffinity(getpid(), sizeof(cpu_set), &cpu_set); perror("sched_setaffinity"); return ret ? EXIT_FAILURE : EXIT_SUCCESS; } The mistake is that suspend is handled in the action == CPU_DOWN_PREPARE_FROZEN case of the switch statement in cpuset_cpu_inactive(). However, the commit in question masked out CPU_TASKS_FROZEN from the action, making this case dead. The fix is straightforward. Signed-off-by: Omar Sandoval Signed-off-by: Peter Zijlstra (Intel) Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Juri Lelli Cc: Thomas Gleixner Fixes: 3c18d447b3b3 ("sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()") Link: http://lkml.kernel.org/r/1cb5ecb3d6543c38cce5790387f336f54ec8e2bc.1430733960.git.osandov@osandov.com Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 28 ++++++++++++---------------- 1 file changed, 12 insertions(+), 16 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 34db9bf892a3..57bd333bc4ab 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6999,27 +6999,23 @@ static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, unsigned long flags; long cpu = (long)hcpu; struct dl_bw *dl_b; + bool overflow; + int cpus; - switch (action & ~CPU_TASKS_FROZEN) { + switch (action) { case CPU_DOWN_PREPARE: - /* explicitly allow suspend */ - if (!(action & CPU_TASKS_FROZEN)) { - bool overflow; - int cpus; - - rcu_read_lock_sched(); - dl_b = dl_bw_of(cpu); + rcu_read_lock_sched(); + dl_b = dl_bw_of(cpu); - raw_spin_lock_irqsave(&dl_b->lock, flags); - cpus = dl_bw_cpus(cpu); - overflow = __dl_overflow(dl_b, cpus, 0, 0); - raw_spin_unlock_irqrestore(&dl_b->lock, flags); + raw_spin_lock_irqsave(&dl_b->lock, flags); + cpus = dl_bw_cpus(cpu); + overflow = __dl_overflow(dl_b, cpus, 0, 0); + raw_spin_unlock_irqrestore(&dl_b->lock, flags); - rcu_read_unlock_sched(); + rcu_read_unlock_sched(); - if (overflow) - return notifier_from_errno(-EBUSY); - } + if (overflow) + return notifier_from_errno(-EBUSY); cpuset_update_active_cpus(false); break; case CPU_DOWN_PREPARE_FROZEN: -- 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/