From: Oleg Nesterov <oleg@redhat.com>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Pavel Machek <pavel@ucw.cz>, Denys Vlasenko <dvlasenk@redhat.com>,
jan.kratochvil@redhat.com, palves@redhat.com,
Roland McGrath <roland@hack.frob.com>,
syzkaller <syzkaller@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: Unkillable processes due to PTRACE_TRACEME again
Date: Mon, 5 Dec 2016 11:46:52 +0100 [thread overview]
Message-ID: <20161205104652.GA29197@redhat.com> (raw)
In-Reply-To: <CACT4Y+ZnT3ngSvbs=U8=41TAMpaS8YqbVb7KdiK9QTM7Jd+JgA@mail.gmail.com>
On 12/02, Dmitry Vyukov wrote:
>
> I am not on 2caceb3294a78c389b462e7e236a4e744a53a474 (Dec 1). And see
> the same unwaitable zombie processes.
This is another thing, and notabug. This is how ptrace works,
> void *thr(void *arg)
> {
> ptrace(PTRACE_TRACEME, 0, 0, 0);
> }
>
> int main()
> {
> int pid = fork();
> if (pid == 0) {
> pthread_t th;
> pthread_create(&th, 0, thr, 0);
> usleep(100000);
> exit(0);
> }
> usleep(200000);
> kill(pid, SIGKILL);
> int status = 0;
> waitpid(pid, &status, __WALL);
waitpid(pid) hangs because you need to reap the sub-thread first.
Oleg.
next prev parent reply other threads:[~2016-12-05 10:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-02 18:48 Unkillable processes due to PTRACE_TRACEME again Dmitry Vyukov
2016-12-02 21:02 ` Pavel Machek
2016-12-03 15:55 ` Dmitry Vyukov
2016-12-03 19:11 ` Pavel Machek
2016-12-05 10:46 ` Oleg Nesterov [this message]
2016-12-05 11:00 ` Oleg Nesterov
2016-12-05 14:07 ` Dmitry Vyukov
2016-12-05 16:59 ` Oleg Nesterov
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=20161205104652.GA29197@redhat.com \
--to=oleg@redhat.com \
--cc=dvlasenk@redhat.com \
--cc=dvyukov@google.com \
--cc=jan.kratochvil@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=palves@redhat.com \
--cc=pavel@ucw.cz \
--cc=roland@hack.frob.com \
--cc=syzkaller@googlegroups.com \
/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).