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Date: Mon, 22 Jan 2024 14:44:46 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Kees Cook <keescook@chromium.org>,
	Andy Lutomirski <luto@amacapital.net>,
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	Christian Brauner <brauner@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>, Serge Hallyn <serge@hallyn.com>,
	James Morris <jamorris@linux.microsoft.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Yafang Shao <laoar.shao@gmail.com>, Helge Deller <deller@gmx.de>,
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	Adrian Reber <areber@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>, Jens Axboe <axboe@kernel.dk>,
	Alexei Starovoitov <ast@kernel.org>,
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	tiozhang <tiozhang@didiglobal.com>,
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	Frederic Weisbecker <frederic@kernel.org>,
	YueHaibing <yuehaibing@huawei.com>,
	Paul Moore <paul@paul-moore.com>, Aleksa Sarai <cyphar@cyphar.com>,
	Stefan Roesch <shr@devkernel.io>, Chao Yu <chao@kernel.org>,
	xu xin <xu.xin16@zte.com.cn>, Jeff Layton <jlayton@kernel.org>,
	Jan Kara <jack@suse.cz>, David Hildenbrand <david@redhat.com>,
	Dave Chinner <dchinner@redhat.com>, Shuah Khan <shuah@kernel.org>,
	Zheng Yejian <zhengyejian1@huawei.com>,
	Elena Reshetova <elena.reshetova@intel.com>,
	David Windsor <dwindsor@gmail.com>,
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	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Hans Liljestrand <ishkamiel@gmail.com>
Subject: Re: [PATCH v14] exec: Fix dead-lock in de_thread with ptrace_attach
Message-ID: <20240122134446.GB22901@redhat.com>
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User-Agent: Mutt/1.5.24 (2015-08-30)

I'll try to read your email later, just one note for now...

On 01/22, Bernd Edlinger wrote:
>
> > I didn't say that t is a group leader. I said it can be a zombie sub-thread
> > with ->exit_state != 0.
>
> the condition here is
>
> (t != tsk->group_leader || !t->exit_state)
>
> so in other words, if t is a sub-thread, i.e. t != tsk->group_leader
> then the t->exit_state does not count,

Ah indeed, somehow I misread this check as if you skip the sub-threads
with ->exit_state != 0.

Sorry for noise.

Oleg.