linux-kernel - Re: [PATCH 0/2] finx argv

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Message-ID: <20130316205634.GU11268@two.firstfloor.org>
Date:	Sat, 16 Mar 2013 21:56:34 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Lucas De Marchi <lucas.de.marchi@...il.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@...ba.org>, david@...son.dropbear.id.au,
	Kees Cook <keescook@...omium.org>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Feng Hong <hongfeng@...vell.com>,
	Lucas De Marchi <lucas.demarchi@...fusion.mobi>
Subject: Re: [PATCH 0/2] finx argv_split() vs sysctl race

> Perhaps rcu can be better, although a global rwsem looks simpler,
> I dunno.

It's a general problem with lots of sysctls.
> 
> But argv_split() or its usage should be changed anyway, and GFP_KERNEL
> won't work under rcu_read_lock().

rcu strings has a helper function to copy the string for sleepy cases.

> 
> To me 1/2 looks as a simplification anyway, but I won't argue if we
> decide to add rcu/locking and avoid this patch.

Ok I'll revisit. I think the problem last time was that the rcu strings
needed a kernel_text_address() function that worked on all
architectures.

Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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