From: Oleg Nesterov <oleg@redhat.com>
To: qianli zhao <zhaoqianligood@gmail.com>
Cc: christian@brauner.io, axboe@kernel.dk,
"Eric W. Biederman" <ebiederm@xmission.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Collingbourne <pcc@google.com>,
linux-kernel@vger.kernel.org, Qianli Zhao <zhaoqianli@xiaomi.com>
Subject: Re: [PATCH V3] exit: trigger panic when global init has exited
Date: Thu, 18 Mar 2021 19:04:51 +0100 [thread overview]
Message-ID: <20210318180450.GA9977@redhat.com> (raw)
In-Reply-To: <CAPx_LQG=tj+kM14wS79tLPJbVjC+79OFDgfv6zai_sJ74CGeug@mail.gmail.com>
On 03/18, qianli zhao wrote:
>
> Hi,Oleg
>
> Thank you for your reply.
>
> >> When init sub-threads running on different CPUs exit at the same time,
> >> zap_pid_ns_processe()->BUG() may be happened.
>
> > and why do you think your patch can't prevent this?
>
> > Sorry, I must have missed something. But it seems to me that you are trying
> > to fix the wrong problem. Yes, zap_pid_ns_processes() must not be called in
> > the root namespace, and this has nothing to do with CONFIG_PID_NS.
>
> Yes, i try to fix this exception by test SIGNAL_GROUP_EXIT and call
> panic before setting PF_EXITING to prevent zap_pid_ns_processes()
> being called when init do_exit().
Ah, I didn't notice your patch does atomic_dec_and_test(signal->live)
before exit_signals() which sets PF_EXITING. Thanks for correcting me.
So yes, I was wrong, your patch can prevent this. Although I'd like to
recheck if every do-something-if-group-dead action is correct in the
case we have a non-PF_EXITING thread...
But then I don't understand the SIGNAL_GROUP_EXIT check added by your
patch. Do we really need it if we want to avoid zap_pid_ns_processes()
when the global init exits?
> In addition, the patch also protects the init process state to
> successfully get usable init coredump.
Could you spell please?
Does this connect to SIGNAL_GROUP_EXIT check? Do you mean that you want
to panic earlier, before other init's sub-threads exit?
Thanks,
Oleg.
next prev parent reply other threads:[~2021-03-18 18:06 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 12:51 [PATCH V3] exit: trigger panic when global init has exited Qianli Zhao
2021-03-17 14:38 ` Oleg Nesterov
2021-03-18 2:47 ` qianli zhao
2021-03-18 18:04 ` Oleg Nesterov [this message]
2021-03-18 19:08 ` Eric W. Biederman
2021-03-19 6:33 ` qianli zhao
2021-03-19 16:34 ` Oleg Nesterov
2021-03-19 16:26 ` Oleg Nesterov
2021-03-21 16:00 ` qianli zhao
2021-03-22 17:07 ` Oleg Nesterov
2021-03-22 17:09 ` Oleg Nesterov
2021-03-19 5:08 ` qianli zhao
2021-03-19 16:32 ` Oleg Nesterov
2021-03-21 13:04 ` qianli zhao
2021-03-22 16:37 ` Oleg Nesterov
2021-03-23 3:14 ` qianli zhao
2021-03-23 9:00 ` Oleg Nesterov
2021-03-23 11:23 ` qianli zhao
2021-03-24 18:12 ` Oleg Nesterov
2021-03-25 3:00 ` qianli zhao
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