linux-kernel - Re: [v3.13][v3.14][Regression] kthread: make kthread

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 18 Mar 2014 06:32:56 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:	akpm@...ux-foundation.org, joseph.salisbury@...onical.com
Cc:	oleg@...hat.com, rientjes@...gle.com,
	torvalds@...ux-foundation.org, tj@...nel.org, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, kernel-team@...ts.ubuntu.com
Subject: Re: [v3.13][v3.14][Regression] kthread: make kthread_create()killable

Andrew Morton wrote:
> What process is running here?  Presumably modprobe.

Yes. It is a worker systemd-udevd process who is acting like modprobe .

> A possible explanation is that modprobe has genuinely received a
> SIGKILL.  Can you identify anything in this setup which might send a
> SIGKILL to the modprobe process?

It is the systemd-udevd process who is sending SIGKILL to worker
systemd-udevd processes. It uses hard coded 30 seconds timeout.

> kthread_create_on_node() thinks that SIGKILL came from the oom-killer
> and it cheerfully returns -ENOMEM, which is incorrect if that signal
> came from userspace.  And I don't _think_ we prevent
> userspace-originated signals from unblocking
> wait_for_completion_killable()?

I prefer processes being killed upon SIGKILL as soon as possible.
I expect any unkillable operations should be replaced with killable
operations, or the OOM killer may fail to solve no memory state by
choosing a process in unkillable sleep.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/