linux-kernel - Re: [PATCH 2/6] uprobes: introduce is_swbp_at_addr

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Message-ID: <20120416153408.GA8852@redhat.com>
Date:	Mon, 16 Apr 2012 17:34:08 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux-mm <linux-mm@...ck.org>, Andi Kleen <andi@...stfloor.org>,
	Christoph Hellwig <hch@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Anton Arapov <anton@...hat.com>
Subject: Re: [PATCH 2/6] uprobes: introduce is_swbp_at_addr_fast()

On 04/16, Peter Zijlstra wrote:
>
> Can't we 'optimize' read_opcode() by doing the pagefault_disable() +
> __copy_from_user_inatomic() optimistically before going down the whole
> gup()+lock+kmap path?

Unlikely, the task is not current.

Oleg.

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