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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CCB6BC32771 for ; Fri, 19 Aug 2022 11:22:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348780AbiHSLWm (ORCPT ); Fri, 19 Aug 2022 07:22:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51872 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348787AbiHSLWj (ORCPT ); Fri, 19 Aug 2022 07:22:39 -0400 Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D85D7FEC40 for ; Fri, 19 Aug 2022 04:22:37 -0700 (PDT) Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4M8K9P1v8Qz4x1G; Fri, 19 Aug 2022 21:22:33 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1660908155; bh=SXvhcATHeAzGrsMP2ajJM02RREFpXI38PV8xlqpBvfk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=Dj5/0PZNbcvmmBLC1vxc+g8hIrgyxyVrvDiueNMAUKwl+xNjN80XyTFh6mcL3oo88 JhI4NCwCYx4vx1guEND4xEfN602aY988zTA9BEVr/wBtSUBng7mjVYFRd54CfaNV7L AzlxqMoecTz26IeIoVfSYwYkbqdW/dWTJBpg7v+Df9GFmEHhjHTzfNo5Cc+h8jBBGN /wTMmny+SRgk1jqhkGFt+qR/9XwyQ8/ZL3licVyZcBan4ftPMvNnrJY4G8bpPi6g62 boV22S7BcUl47iUzKvn+Zwpcp+K42mIHbBDhssIFl1XIJKxDOfb8hanzYqJ34Hy+qF 49CXJER8bAuPg== From: Michael Ellerman To: Mike Kravetz , Andrew Morton Cc: "Wang, Haiyue" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "david@redhat.com" , "apopple@nvidia.com" , "linmiaohe@huawei.com" , "Huang, Ying" , "songmuchun@bytedance.com" , "naoya.horiguchi@linux.dev" , "alex.sierra@amd.com" , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Subject: Re: [PATCH v6 1/2] mm: migration: fix the FOLL_GET failure on following huge page In-Reply-To: References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220816022102.582865-1-haiyue.wang@intel.com> <20220816022102.582865-2-haiyue.wang@intel.com> <20220816175838.211a1b1e85bc68c439101995@linux-foundation.org> <20220816224322.33e0dfbcbf522fcdc2026f0e@linux-foundation.org> Date: Fri, 19 Aug 2022 21:22:32 +1000 Message-ID: <875yiomq9z.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mike Kravetz writes: > On 08/16/22 22:43, Andrew Morton wrote: >> On Wed, 17 Aug 2022 03:31:37 +0000 "Wang, Haiyue" wrote: >> >> > > > } >> > > >> > > I would be better to fix this for real at those three client code sites? >> > >> > Then 5.19 will break for a while to wait for the final BIG patch ? >> >> If that's the proposal then your [1/2] should have had a cc:stable and >> changelog words describing the plan for 6.0. >> >> But before we do that I'd like to see at least a prototype of the final >> fixes to s390 and hugetlb, so we can assess those as preferable for >> backporting. I don't think they'll be terribly intrusive or risky? > > I will start on adding follow_huge_pgd() support. Although, I may need > some help with verification from the powerpc folks, as that is the only > architecture which supports hugetlb pages at that level. > > mpe any suggestions? I'm happy to test. I have a system where I can allocate 1GB huge pages. I'm not sure how to actually test this path though. I hacked up the vm/migration.c test to allocate 1GB hugepages, but I can't see it going through follow_huge_pgd() (using ftrace). Maybe I hacked it up badly, I'll have a closer look on Monday. But if you have any tips on how to trigger that path let me know :) cheers