Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753543AbdGNJPB (ORCPT ); Fri, 14 Jul 2017 05:15:01 -0400 Received: from terminus.zytor.com ([65.50.211.136]:33641 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750853AbdGNJO6 (ORCPT ); Fri, 14 Jul 2017 05:14:58 -0400 Date: Fri, 14 Jul 2017 02:10:14 -0700 From: tip-bot for Wanpeng Li Message-ID: Cc: wanpeng.li@hotmail.com, torvalds@linux-foundation.org, riel@redhat.com, peterz@infradead.org, tglx@linutronix.de, hpa@zytor.com, lcapitulino@redhat.com, linux-kernel@vger.kernel.org, xiaolong.ye@intel.com, fweisbec@gmail.com, mingo@kernel.org Reply-To: riel@redhat.com, peterz@infradead.org, wanpeng.li@hotmail.com, torvalds@linux-foundation.org, xiaolong.ye@intel.com, fweisbec@gmail.com, mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com, lcapitulino@redhat.com, linux-kernel@vger.kernel.org In-Reply-To: <1499586028-7402-1-git-send-email-wanpeng.li@hotmail.com> References: <1499586028-7402-1-git-send-email-wanpeng.li@hotmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched/cputime: Don't use smp_processor_id() in preemptible context Git-Commit-ID: 0e4097c3354e2f5a5ad8affd9dc7f7f7d00bb6b9 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2848 Lines: 83 Commit-ID: 0e4097c3354e2f5a5ad8affd9dc7f7f7d00bb6b9 Gitweb: http://git.kernel.org/tip/0e4097c3354e2f5a5ad8affd9dc7f7f7d00bb6b9 Author: Wanpeng Li AuthorDate: Sun, 9 Jul 2017 00:40:28 -0700 Committer: Ingo Molnar CommitDate: Fri, 14 Jul 2017 10:27:15 +0200 sched/cputime: Don't use smp_processor_id() in preemptible context Recent kernels trigger this warning: BUG: using smp_processor_id() in preemptible [00000000] code: 99-trinity/181 caller is debug_smp_processor_id+0x17/0x19 CPU: 0 PID: 181 Comm: 99-trinity Not tainted 4.12.0-01059-g2a42eb9 #1 Call Trace: dump_stack+0x82/0xb8 check_preemption_disabled() debug_smp_processor_id() vtime_delta() task_cputime() thread_group_cputime() thread_group_cputime_adjusted() wait_consider_task() do_wait() SYSC_wait4() do_syscall_64() entry_SYSCALL64_slow_path() As Frederic pointed out: | Although those sched_clock_cpu() things seem to only matter when the | sched_clock() is unstable. And that stability is a condition for nohz_full | to work anyway. So probably sched_clock() alone would be enough. This patch fixes it by replacing sched_clock_cpu() with sched_clock() to avoid calling smp_processor_id() in a preemptible context. Reported-by: Xiaolong Ye Signed-off-by: Wanpeng Li Cc: Frederic Weisbecker Cc: Linus Torvalds Cc: Luiz Capitulino Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1499586028-7402-1-git-send-email-wanpeng.li@hotmail.com [ Prettified the changelog. ] Signed-off-by: Ingo Molnar --- kernel/sched/cputime.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 6e3ea4a..14d2dbf 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -683,7 +683,7 @@ static u64 vtime_delta(struct vtime *vtime) { unsigned long long clock; - clock = sched_clock_cpu(smp_processor_id()); + clock = sched_clock(); if (clock < vtime->starttime) return 0; @@ -814,7 +814,7 @@ void arch_vtime_task_switch(struct task_struct *prev) write_seqcount_begin(&vtime->seqcount); vtime->state = VTIME_SYS; - vtime->starttime = sched_clock_cpu(smp_processor_id()); + vtime->starttime = sched_clock(); write_seqcount_end(&vtime->seqcount); } @@ -826,7 +826,7 @@ void vtime_init_idle(struct task_struct *t, int cpu) local_irq_save(flags); write_seqcount_begin(&vtime->seqcount); vtime->state = VTIME_SYS; - vtime->starttime = sched_clock_cpu(cpu); + vtime->starttime = sched_clock(); write_seqcount_end(&vtime->seqcount); local_irq_restore(flags); }