linux-kernel - Re: [RFC PATCH 09/18] kthread: Make it easier to correctly sleep in iterant kthreads

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Message-ID: <20150609073253.GZ21465@mtj.duckdns.org>
Date:	Tue, 9 Jun 2015 16:32:53 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Petr Mladek <pmladek@...e.cz>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	Richard Weinberger <richard@....at>,
	Steven Rostedt <rostedt@...dmis.org>,
	David Woodhouse <dwmw2@...radead.org>,
	linux-mtd@...ts.infradead.org,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	Anna Schumaker <anna.schumaker@...app.com>,
	linux-nfs@...r.kernel.org, Chris Mason <clm@...com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	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>, live-patching@...r.kernel.org,
	linux-api@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 09/18] kthread: Make it easier to correctly sleep in
 iterant kthreads

Hello,

On Mon, Jun 08, 2015 at 12:01:07PM +0200, Petr Mladek wrote:
> BTW: What is the preferred way of freezing, please? Is it better
> to end up in the fridge or is it fine to call freezer_do_not_count();
> or set PF_NOFREEZE when it is safe?

There's no one good answer.  The closest would be "don't use freezer
on kthreads".  As Peter said, exit points are always safe freezing
points and it's generally a good idea to avoid adding one anywhere
else.

Thanks.

-- 
tejun
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