linux-kernel - Re: [PATCH v4 04/22] kthread: Add create_kthread

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Message-ID: <20160216160801.GM3741@mtj.duckdns.org>
Date:	Tue, 16 Feb 2016 11:08:01 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Petr Mladek <pmladek@...e.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Josh Triplett <josh@...htriplett.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jiri Kosina <jkosina@...e.cz>, Borislav Petkov <bp@...e.de>,
	Michal Hocko <mhocko@...e.cz>, linux-mm@...ck.org,
	Vlastimil Babka <vbabka@...e.cz>, linux-api@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 04/22] kthread: Add create_kthread_worker*()

Hello,

On Tue, Feb 16, 2016 at 04:44:43PM +0100, Petr Mladek wrote:
> I wanted to be sure. The cpu number is later passed to
> cpu_to_node(cpu) in kthread_create_on_cpu().
> 
> I am going to replace this with a check against nr_cpu_ids in
> kthread_create_on_cpu() which makes more sense.
> 
> I might be too paranoid. But this is slow path. People
> do mistakes...

idk, that just ended up adding a subtly broken code which checks for
an unlikely condition which would cause a crash anyway.  I don't see
the point.  If you want to insist on it, please at least make it a
WARN_ON().  It's a clear kernel bug.

Thanks.

-- 
tejun