From: Oleg Nesterov <oleg@redhat.com>
To: "Jürg Billeter" <j@bitron.ch>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Kees Cook <keescook@chromium.org>,
Andy Lutomirski <luto@kernel.org>,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT
Date: Fri, 30 Nov 2018 11:33:30 +0100 [thread overview]
Message-ID: <20181130103329.GB23670@redhat.com> (raw)
In-Reply-To: <f55261dbc41544363b4348820f67fb01c6d7aaec.camel@bitron.ch>
On 11/29, Jürg Billeter wrote:
>
> On Thu, 2018-11-29 at 13:34 +0100, Oleg Nesterov wrote:
> > To me it would be more clean to call walk_process_tree(kill_descendant_visitor)
> > unconditionally in find_new_reaper() right before "if (has_child_subreaper)", but
> > then we will need to shift read_lock(tasklist) from walk_process_tree().
>
> Yes, that's the reason why I added the call before the tasklist lock.
> Let me know if you want me to move the read lock from
> walk_process_tree() to PR_SET_CHILD_SUBREAPER (the only caller)
> instead.
I am fine either way. We can do this later, lets keep your patch simple.
> > So I think the patch is mostly fine, the only problem I can see is that
> > PR_SET_KILL_DESCENDANTS_ON_EXIT can race with PR_SET_CHILD_SUBREAPER, they both
> > need to update the bits in the same word.
>
> Good point. I'll make it a regular bool instead of a bitfield for v2,
Agreed,
> unless you have another approach in mind to fix this.
Well, I think that is_child_subreaper/has_child_subreaper and the new
kill_descendants_on_exit should live in signal->flags, but we need some
cleanups to make this possible, so I agree with the boolean.
Oleg.
next prev parent reply other threads:[~2018-11-30 10:33 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 22:54 [PATCH 0/1] Add prctl to kill descendants on exit Jürg Billeter
2018-11-27 22:54 ` [PATCH] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT Jürg Billeter
2018-11-28 14:42 ` Oleg Nesterov
2018-11-28 15:23 ` Eric W. Biederman
2018-11-29 12:34 ` Oleg Nesterov
2018-11-29 15:41 ` Jürg Billeter
2018-11-30 10:33 ` Oleg Nesterov [this message]
2018-12-01 4:28 ` Kees Cook
2018-11-30 8:00 ` [PATCH v2 0/1] Add prctl to kill descendants on exit Jürg Billeter
2018-11-30 8:00 ` [PATCH v2 1/1] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT Jürg Billeter
2018-11-30 11:22 ` Oleg Nesterov
2018-11-30 13:40 ` Florian Weimer
2018-12-01 10:39 ` Jürg Billeter
2018-12-01 12:28 ` Florian Weimer
2018-12-01 13:57 ` Jürg Billeter
2018-12-06 15:54 ` [PATCH v2 0/1] Add prctl to kill descendants on exit Jürg Billeter
2019-01-18 13:11 ` [RESEND PATCH " Jürg Billeter
2019-01-18 13:11 ` [RESEND PATCH v2 1/1] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT Jürg Billeter
2019-01-29 1:23 ` Andrew Morton
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