From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xGT5345mvzDrFG for ; Tue, 25 Jul 2017 03:34:15 +1000 (AEST) Date: Mon, 24 Jul 2017 19:34:02 +0200 Message-ID: <20170724193402.Horde.6aHXbQVl2cfpW3l9leYB8Q2@messagerie.c-s.fr> From: LEROY Christophe To: Michael Ellerman Cc: aneesh.kumar@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, Benjamin Herrenschmidt Subject: Re: [PATCH 23/24] powerpc/mm: Cleanup check for stack expansion References: <20170719044946.22030-1-benh@kernel.crashing.org> <20170719044946.22030-23-benh@kernel.crashing.org> <20170721185947.Horde.e8_0DAuKLUb1znI0Zfx-aQ2@messagerie.c-s.fr> <87pocqjemx.fsf@concordia.ellerman.id.au> In-Reply-To: <87pocqjemx.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=UTF-8; format=flowed; DelSp=Yes MIME-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Michael Ellerman a =C3=A9crit=C2=A0: > LEROY Christophe writes: > >> Benjamin Herrenschmidt a =C3=A9crit=C2=A0: >> >>> When hitting below a VM_GROWSDOWN vma (typically growing the stack), >>> we check whether it's a valid stack-growing instruction and we >>> check the distance to GPR1. This is largely open coded with lots >>> of comments, so move it out to a helper. >> >> Did you have a look at the following patch ? It's been waiting for >> application for some weeks now. >> https://patchwork.ozlabs.org/patch/771869 > > I actually merged it last merge window, but found I had no good way to > test it, so I took it out again until I can write a test case for it. > > The way I realised it wasn't being tested was by removing all the > store_updates_sp logic entirely and having my system run happily for > several days :} Which demonstrates how unlikely this is, hence doing that get_user()=20=20 at=20every fault is waste of time. How do you plan to handle that in parralele to ben's serie ? I'll be back from vacation next week and may help finding a way to=20=20 test=20that. (A test program using alloca() ?) Christophe > > cheers