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: Fri, 19 Mar 2021 17:32:25 +0100 [thread overview]
Message-ID: <20210319163225.GB19971@redhat.com> (raw)
In-Reply-To: <CAPx_LQENxx0y5mFJjwRT2qMSLt7pbAmF30=eE-QduEwRVJEJ0Q@mail.gmail.com>
On 03/19, qianli zhao wrote:
>
> > 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?
>
> I think check SIGNAL_GROUP_EXIT is necessary,or panic() will happen
> after all init sub-threads do_exit(),so the following two situations
> will happen:
> 1.According to the timing in the changelog,
> zap_pid_ns_processes()->BUG() maybe happened.
How? Perhaps I missed something again, but I don't think this is possible.
zap_pid_ns_processes() simply won't be called, find_child_reaper() will
see the !PF_EXITING thread which calls panic().
So I think this should be documented somehow, at least in the changelog.
Oleg.
next prev parent reply other threads:[~2021-03-19 16:33 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
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 [this message]
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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