From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f175.google.com (mail-we0-f175.google.com [74.125.82.175]) by kanga.kvack.org (Postfix) with ESMTP id 827D66B0035 for ; Thu, 1 May 2014 05:57:44 -0400 (EDT) Received: by mail-we0-f175.google.com with SMTP id q58so2836052wes.20 for ; Thu, 01 May 2014 02:57:43 -0700 (PDT) Received: from casper.infradead.org (casper.infradead.org. [2001:770:15f::2]) by mx.google.com with ESMTPS id dm4si583098wib.8.2014.05.01.02.57.42 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 May 2014 02:57:43 -0700 (PDT) Date: Thu, 1 May 2014 11:57:39 +0200 From: Peter Zijlstra Subject: Re: [RFC PATCH V4 6/7] arm64: mm: Enable HAVE_RCU_TABLE_FREE logic Message-ID: <20140501095739.GO11096@twins.programming.kicks-ass.net> References: <1396018892-6773-1-git-send-email-steve.capper@linaro.org> <1396018892-6773-7-git-send-email-steve.capper@linaro.org> <20140430152047.GF31220@arm.com> <20140430153317.GG31220@arm.com> <20140430153824.GA7166@linaro.org> <20140430172114.GI31220@arm.com> <20140501073402.GA30358@linaro.org> <20140501095246.GB22316@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140501095246.GB22316@arm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Catalin Marinas Cc: Steve Capper , "linux-arm-kernel@lists.infradead.org" , "linux@arm.linux.org.uk" , "linux-mm@kvack.org" , "linux-arch@vger.kernel.org" , "gary.robertson@linaro.org" , "anders.roxell@linaro.org" , "akpm@linux-foundation.org" On Thu, May 01, 2014 at 10:52:47AM +0100, Catalin Marinas wrote: > Does gup_fast walking increment the mm_users? Or is it a requirement of > the calling code? I can't seem to find where this happens. No, its not required at all. One should only walk current->mm with gup_fast, any other usage is broken. And by delaying TLB shootdown, either through disabling IRQs and stalling IPIs or by using RCU freeing, you're guaranteed your own page tables won't disappear underneath your feet. -- 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/ . Don't email: email@kvack.org