From: Frederic Weisbecker <frederic@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Wanpeng Li <wanpengli@tencent.com>,
Thomas Gleixner <tglx@linutronix.de>,
Yauheni Kaliuta <yauheni.kaliuta@redhat.com>,
Ingo Molnar <mingo@kernel.org>, Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 20/25] sched/kcpustat: Introduce vtime-aware kcpustat accessor
Date: Tue, 20 Nov 2018 23:40:22 +0100 [thread overview]
Message-ID: <20181120224021.GB22332@lerouge> (raw)
In-Reply-To: <20181120142306.GX2131@hirez.programming.kicks-ass.net>
On Tue, Nov 20, 2018 at 03:23:06PM +0100, Peter Zijlstra wrote:
> On Wed, Nov 14, 2018 at 03:46:04AM +0100, Frederic Weisbecker wrote:
>
> > +void kcpustat_cputime(struct kernel_cpustat *kcpustat, int cpu,
> > + u64 *user, u64 *nice, u64 *system,
> > + u64 *guest, u64 *guest_nice)
> > +{
> > + struct task_struct *curr;
> > + struct vtime *vtime;
> > + int err;
> > +
> > + if (!vtime_accounting_enabled()) {
> > + kcpustat_cputime_raw(kcpustat, user, nice,
> > + system, guest, guest_nice);
> > + return;
> > + }
> > +
> > + rcu_read_lock();
> > +
> > + do {
> > + curr = rcu_dereference(kcpustat->curr);
>
> Like I explained earlier; I don't think the above is correct.
> task_struct is itself not RCU protected.
But there is at least one put_task_struct() that is enqueued as an RCU callback
on release_task(). That patchset (try to) make sure that kcpustat->curr can't
be assigned beyond that point.
Or did I misunderstand something?
next prev parent reply other threads:[~2018-11-20 22:40 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-14 2:45 [PATCH 00/25] sched/nohz: Make kcpustat vtime aware (Fix kcpustat on nohz_full) Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 01/25] sched/vtime: Fix guest/system mis-accounting on task switch Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 02/25] sched/vtime: Protect idle accounting under vtime seqcount Frederic Weisbecker
2018-11-20 13:19 ` Peter Zijlstra
2018-11-14 2:45 ` [PATCH 03/25] vtime: Rename vtime_account_system() to vtime_account_kernel() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 04/25] vtime: Spare a seqcount lock/unlock cycle on context switch Frederic Weisbecker
2018-11-20 13:25 ` Peter Zijlstra
2019-09-25 14:42 ` Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 05/25] sched/vtime: Record CPU under seqcount for kcpustat needs Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 06/25] sched/cputime: Add vtime idle task state Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 07/25] sched/cputime: Add vtime guest " Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 08/25] vtime: Exit vtime before exit_notify() Frederic Weisbecker
2018-11-20 13:54 ` Peter Zijlstra
2018-11-14 2:45 ` [PATCH 09/25] kcpustat: Track running task following vtime sequences Frederic Weisbecker
2018-11-20 13:58 ` Peter Zijlstra
2018-11-14 2:45 ` [PATCH 10/25] context_tracking: Remove context_tracking_active() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 11/25] context_tracking: s/context_tracking_is_enabled/context_tracking_enabled() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 12/25] context_tracking: Rename context_tracking_is_cpu_enabled() to context_tracking_enabled_this_cpu() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 13/25] context_tracking: Introduce context_tracking_enabled_cpu() Frederic Weisbecker
2018-11-20 14:02 ` Peter Zijlstra
2018-11-14 2:45 ` [PATCH 14/25] sched/vtime: Rename vtime_accounting_cpu_enabled() to vtime_accounting_enabled_this_cpu() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 15/25] sched/vtime: Introduce vtime_accounting_enabled_cpu() Frederic Weisbecker
2018-11-20 14:04 ` Peter Zijlstra
2018-11-14 2:46 ` [PATCH 16/25] sched/cputime: Allow to pass cputime index on user/guest accounting Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 17/25] sched/cputime: Standardize the kcpustat index based accounting functions Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 18/25] vtime: Track nice-ness on top of context switch Frederic Weisbecker
2018-11-20 14:09 ` Peter Zijlstra
2018-11-14 2:46 ` [PATCH 19/25] sched/vite: Handle nice updates under vtime Frederic Weisbecker
2018-11-20 14:17 ` Peter Zijlstra
2018-11-26 15:53 ` Frederic Weisbecker
2018-11-26 16:11 ` Peter Zijlstra
2018-11-26 18:41 ` Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 20/25] sched/kcpustat: Introduce vtime-aware kcpustat accessor Frederic Weisbecker
2018-11-20 14:23 ` Peter Zijlstra
2018-11-20 22:40 ` Frederic Weisbecker [this message]
2018-11-21 8:18 ` Peter Zijlstra
2018-11-21 8:35 ` Peter Zijlstra
2018-11-21 16:33 ` Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 21/25] procfs: Use vtime aware " Frederic Weisbecker
2018-11-20 14:24 ` Peter Zijlstra
2018-11-20 22:31 ` Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 22/25] cpufreq: " Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 23/25] leds: Use vtime aware kcpustat accessors Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 24/25] rackmeter: " Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 25/25] sched/vtime: Clarify vtime_task_switch() argument layout Frederic Weisbecker
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181120224021.GB22332@lerouge \
--to=frederic@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
--cc=tglx@linutronix.de \
--cc=wanpengli@tencent.com \
--cc=yauheni.kaliuta@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).