linux-kernel - Re: deferring _

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Message-ID: <1340625805.2507.56.camel@laptop>
Date:	Mon, 25 Jun 2012 14:03:25 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	". James Morris" <jmorris@...ei.org>,
	linux-security-module@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Oleg Nesterov <oleg@...hat.com>,
	David Miller <davem@...emloft.net>
Subject: Re: deferring __fput()

On Sat, 2012-06-23 at 21:57 +0100, Al Viro wrote:
> 3) at that point task_work is equal in size (and layout, BTW) to rcu_head.  So we can add it
> into the same union in struct file where we already have list_head and rcu_head.  No space
> eaten up.  fput() would, once the counter reaches 0, remove the file from list (the only
> place walking that list skips the ones with zero refcount anyway) and, if we are in a normal
> process, use task_work_add() to have __fput() done to it.  If we are in kernel thread or
> atomic context, just move the sucker to global list and use schedule_work() to have said
> list emptied and everything in it fed to __fput(). 

So we're now Ok with doing fput() async?

Last time I remember this coming up people thought this wasn't such a
hot idea.

  https://lkml.org/lkml/2010/1/5/208



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