linux-next.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Qian Cai <cai@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@kernel.org>, x86 <x86@kernel.org>,
	linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
	Linux Next Mailing List <linux-next@vger.kernel.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Boqun Feng <boqun.feng@gmail.com>
Subject: Re: [tip: locking/core] lockdep: Fix lockdep recursion
Date: Fri, 09 Oct 2020 13:54:34 -0400	[thread overview]
Message-ID: <942e0ffb37a4580982206d72404c521d72d38314.camel@redhat.com> (raw)
In-Reply-To: <e8fce9c0db7985e132262fd508a519ade656bdd8.camel@redhat.com>

On Fri, 2020-10-09 at 13:36 -0400, Qian Cai wrote:
> Back to x86, we have:
> 
> start_secondary()
>   smp_callin()
>     apic_ap_setup()
>       setup_local_APIC()
>         printk() in certain conditions.
> 
> which is before smp_store_cpu_info().
> 
> Can't we add a rcu_cpu_starting() at the very top for each start_secondary(),
> secondary_start_kernel(), smp_start_secondary() etc, so we don't worry about
> any printk() later?

This is rather irony. rcu_cpu_starting() is taking a lock and then reports
itself.

[    8.826732][    T0]  __lock_acquire.cold.76+0x2ad/0x3e0
[    8.826732][    T0]  lock_acquire+0x1c8/0x820
[    8.826732][    T0]  _raw_spin_lock_irqsave+0x30/0x50
[    8.826732][    T0]  rcu_cpu_starting+0xd0/0x2c0
[    8.826732][    T0]  start_secondary+0x10/0x2a0
[    8.826732][    T0]  secondary_startup_64_no_verify+0xb8/0xbb



  parent reply	other threads:[~2020-10-09 17:54 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <160223032121.7002.1269740091547117869.tip-bot2@tip-bot2>
2020-10-09 13:41 ` [tip: locking/core] lockdep: Fix lockdep recursion Qian Cai
2020-10-09 13:58   ` Paul E. McKenney
2020-10-09 15:30     ` Qian Cai
2020-10-09 16:11       ` Paul E. McKenney
2020-10-09 16:23     ` Peter Zijlstra
2020-10-09 16:37       ` Paul E. McKenney
2020-10-09 17:36       ` Qian Cai
2020-10-09 17:50         ` Paul E. McKenney
2020-10-09 17:54         ` Qian Cai [this message]
2020-10-09 18:21           ` Paul E. McKenney
2020-10-12  3:11   ` Boqun Feng
2020-10-12 14:14     ` Qian Cai
2020-10-12 21:28     ` Paul E. McKenney
2020-10-13 10:34       ` Peter Zijlstra
2020-10-13 10:44         ` Peter Zijlstra
2020-10-13 11:25           ` Peter Zijlstra
2020-10-13 16:26             ` Paul E. McKenney
2020-10-13 19:30               ` Paul E. McKenney
2020-10-14 18:34                 ` Paul E. McKenney
2020-10-14 21:53                   ` Peter Zijlstra
2020-10-14 22:11                     ` Paul E. McKenney
2020-10-14 22:39                       ` Peter Zijlstra
2020-10-14 23:55                         ` Paul E. McKenney
2020-10-15  3:41                           ` Paul E. McKenney
2020-10-15  9:49                             ` Peter Zijlstra
2020-10-15  9:50                               ` Peter Zijlstra
2020-10-15 16:15                                 ` Paul E. McKenney
2020-10-15  9:52                               ` Peter Zijlstra
2020-10-15 16:20                                 ` Paul E. McKenney
2020-10-15 16:15                               ` Paul E. McKenney
2020-10-15 17:23                                 ` Paul E. McKenney
2020-10-13 16:15           ` Paul E. McKenney
2020-10-13 10:27     ` Peter Zijlstra
2020-10-13 16:24       ` Boqun Feng
2020-10-27 19:31     ` Qian Cai
2020-10-28  3:01       ` Paul E. McKenney
2020-10-28 14:39         ` Qian Cai
2020-10-28 15:53           ` Paul E. McKenney
2020-10-28 20:08             ` Qian Cai
2020-10-28 21:02               ` Paul E. McKenney

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=942e0ffb37a4580982206d72404c521d72d38314.camel@redhat.com \
    --to=cai@redhat.com \
    --cc=boqun.feng@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-next@vger.kernel.org \
    --cc=linux-tip-commits@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=paulmck@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=sfr@canb.auug.org.au \
    --cc=x86@kernel.org \
    /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).