From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFC1CC282C2 for ; Thu, 7 Feb 2019 19:26:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C6F76206BA for ; Thu, 7 Feb 2019 19:26:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726843AbfBGT0G (ORCPT ); Thu, 7 Feb 2019 14:26:06 -0500 Received: from mx2.suse.de ([195.135.220.15]:36472 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726654AbfBGT0F (ORCPT ); Thu, 7 Feb 2019 14:26:05 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 68F3DAF29; Thu, 7 Feb 2019 19:26:04 +0000 (UTC) Date: Thu, 7 Feb 2019 11:25:55 -0800 From: Davidlohr Bueso To: Paul Burton Cc: "akpm@linux-foundation.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Ralf Baechle , James Hogan , "linux-mips@vger.kernel.org" , Davidlohr Bueso Subject: Re: [PATCH 2/2] MIPS/c-r4k: do no use mmap_sem for gup_fast() Message-ID: <20190207192555.n3qtle4yqmfb2tpo@linux-r8p5> Mail-Followup-To: Paul Burton , "akpm@linux-foundation.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Ralf Baechle , James Hogan , "linux-mips@vger.kernel.org" , Davidlohr Bueso References: <20190207053740.26915-1-dave@stgolabs.net> <20190207053740.26915-3-dave@stgolabs.net> <20190207190007.jz4rz6e6qxwazxm7@pburton-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20190207190007.jz4rz6e6qxwazxm7@pburton-laptop> User-Agent: NeoMutt/20180323 Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Thu, 07 Feb 2019, Paul Burton wrote: >Hi Davidlohr, > >On Wed, Feb 06, 2019 at 09:37:40PM -0800, Davidlohr Bueso wrote: >> It is well known that because the mm can internally >> call the regular gup_unlocked if the lockless approach >> fails and take the sem there, the caller must not hold >> the mmap_sem already. >> >> Fixes: e523f289fe4d (MIPS: c-r4k: Fix sigtramp SMP call to use kmap) >> Cc: Ralf Baechle >> Cc: Paul Burton >> Cc: James Hogan >> Cc: linux-mips@vger.kernel.org >> Signed-off-by: Davidlohr Bueso > >Thanks - this looks good, but: > > 1) The problem it fixes was introduced in v4.8. > > 2) Commit adcc81f148d7 ("MIPS: math-emu: Write-protect delay slot > emulation pages") actually left flush_cache_sigtramp unused, and has > been backported to stable kernels also as far as v4.8. > >Therefore this will just fix code that never gets called, and I'll go >delete the whole thing instead. Even better. Thanks, Davidlohr