From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 44A428D0039 for ; Tue, 8 Mar 2011 21:33:12 -0500 (EST) Date: Wed, 9 Mar 2011 02:33:04 +0000 From: Al Viro Subject: Re: [PATCH 0/6] enable writing to /proc/pid/mem Message-ID: <20110309023303.GZ22723@ZenIV.linux.org.uk> References: <1299631343-4499-1-git-send-email-wilsons@start.ca> <20110309013017.GY22723@ZenIV.linux.org.uk> <20110309021524.GA4838@fibrous.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110309021524.GA4838@fibrous.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Stephen Wilson Cc: linux-mm@kvack.org, Andrew Morton , Rik van Riel , KOSAKI Motohiro , Roland McGrath , Matt Mackall , David Rientjes , Nick Piggin , Andrea Arcangeli , Mel Gorman , Ingo Molnar , Michel Lespinasse , Hugh Dickins , linux-kernel@vger.kernel.org On Tue, Mar 08, 2011 at 09:15:25PM -0500, Stephen Wilson wrote: > I think we could also remove the intermediate copy in both mem_read() and > mem_write() as well, but I think such optimizations could be left for > follow on patches. How? We do copy_.._user() in there; it can trigger page faults and that's not something you want while holding mmap_sem on some mm. Looks like a deadlock country... So we can't do that from inside access_process_vm() or its analogs, which means buffering in caller. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org