From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:49582 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751565AbdGZT4x (ORCPT ); Wed, 26 Jul 2017 15:56:53 -0400 Subject: Patch "sched/cputime: Don't use smp_processor_id() in preemptible context" has been added to the 4.12-stable tree To: wanpeng.li@hotmail.com, fweisbec@gmail.com, gregkh@linuxfoundation.org, lcapitulino@redhat.com, mgorman@suse.de, mingo@kernel.org, peterz@infradead.org, riel@redhat.com, tglx@linutronix.de, torvalds@linux-foundation.org, xiaolong.ye@intel.com Cc: , From: Date: Wed, 26 Jul 2017 12:56:46 -0700 Message-ID: <150109900698174@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled sched/cputime: Don't use smp_processor_id() in preemptible context to the 4.12-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sched-cputime-don-t-use-smp_processor_id-in-preemptible-context.patch and it can be found in the queue-4.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 0e4097c3354e2f5a5ad8affd9dc7f7f7d00bb6b9 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Sun, 9 Jul 2017 00:40:28 -0700 Subject: sched/cputime: Don't use smp_processor_id() in preemptible context From: Wanpeng Li commit 0e4097c3354e2f5a5ad8affd9dc7f7f7d00bb6b9 upstream. 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 Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman --- kernel/sched/cputime.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -683,7 +683,7 @@ static u64 vtime_delta(struct vtime *vti { 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_ 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 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); } Patches currently in stable-queue which might be from wanpeng.li@hotmail.com are queue-4.12/sched-cputime-don-t-use-smp_processor_id-in-preemptible-context.patch queue-4.12/sched-cputime-accumulate-vtime-on-top-of-nsec-clocksource.patch