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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 AEE78C433DF for ; Wed, 8 Jul 2020 07:41:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87AB920656 for ; Wed, 8 Jul 2020 07:41:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594194070; bh=QiMxQc+GA1mkpDvnpswbM0K1G53EGWM+DhSPgG7EKAU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=gvVCL2K1OBSzA6TbWBgtMqrD8tfQSxQzbZYsVe0I139PXVj/G9OTnPV0dO+ROit4y jQUeXq79EiWrorps2xQMYQRQ3l6frwpOTZVMcoG3f2gZGCARSqQ/kWnsuElIt46laI vc1r/s3NP4DEbXMQUZMS5MjFti3Rz6Nv1y7UOow4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726744AbgGHHlJ (ORCPT ); Wed, 8 Jul 2020 03:41:09 -0400 Received: from mail-ej1-f67.google.com ([209.85.218.67]:44994 "EHLO mail-ej1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726523AbgGHHlH (ORCPT ); Wed, 8 Jul 2020 03:41:07 -0400 Received: by mail-ej1-f67.google.com with SMTP id ga4so49256676ejb.11 for ; Wed, 08 Jul 2020 00:41:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=6/A3VQ/K8xvCKHiyxktO8Rg8OAtA4BCJ+I3Yp4ab7mc=; b=NJzm+HIF2hx8/UUUuYmkSUKZ+NW5fJHtFPOu4S88YzzlQQdoafkFhs5Le7U7verTtB oFZwC3+ExXDldatNQV0U2I+OLvM9orHbr/jAhD7esfGpohx+xct2lYBjFi6A69CunYeL 4bPc83J8fhfmLbyo58LGcm4tNAVFwhiOzKqHD3JKM2txMywuC02QsL4/m3qpfTtKmllo 0OhSe8i8mqbqu6m4we8vJIGbb2V2faumUGsehLfjWmZJjiSko0ZZqcfgunX3VLRgQuqS 9Pa5bYEHoo5IHswuf6iayoXLpy3CJmJ3YqJfAX/SSrtDfpMKetGqG7Ktm+AfAQ+xQw2h RSVg== X-Gm-Message-State: AOAM533KvzzTg+z5HziQfbG/WaSLetvDpq4UZDa0Vhda2hTocNiuXQFk 9mKpQ0Gmc1/10k2g2zkTiUk= X-Google-Smtp-Source: ABdhPJykdLeci86uEzWsDP8J/cfe/eHujJtWTsPQHzS01KxobrOSRY5slASSTgDt2Pwhj70aOnSZNA== X-Received: by 2002:a17:906:6d49:: with SMTP id a9mr48950522ejt.435.1594194065679; Wed, 08 Jul 2020 00:41:05 -0700 (PDT) Received: from localhost (ip-37-188-179-51.eurotel.cz. [37.188.179.51]) by smtp.gmail.com with ESMTPSA id dn15sm1605732ejc.26.2020.07.08.00.41.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jul 2020 00:41:04 -0700 (PDT) Date: Wed, 8 Jul 2020 09:41:03 +0200 From: Michal Hocko To: Joonsoo Kim Cc: Vlastimil Babka , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@lge.com, Christoph Hellwig , Roman Gushchin , Mike Kravetz , Naoya Horiguchi Subject: Re: [PATCH v4 04/11] mm/hugetlb: make hugetlb migration callback CMA aware Message-ID: <20200708074103.GD7271@dhcp22.suse.cz> References: <1594107889-32228-1-git-send-email-iamjoonsoo.kim@lge.com> <1594107889-32228-5-git-send-email-iamjoonsoo.kim@lge.com> <20200708071602.GB16543@js1304-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200708071602.GB16543@js1304-desktop> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 08-07-20 16:16:02, Joonsoo Kim wrote: > On Tue, Jul 07, 2020 at 01:22:31PM +0200, Vlastimil Babka wrote: > > On 7/7/20 9:44 AM, js1304@gmail.com wrote: > > > From: Joonsoo Kim > > > > > > new_non_cma_page() in gup.c which try to allocate migration target page > > > requires to allocate the new page that is not on the CMA area. > > > new_non_cma_page() implements it by removing __GFP_MOVABLE flag. This way > > > works well for THP page or normal page but not for hugetlb page. > > > > > > hugetlb page allocation process consists of two steps. First is dequeing > > > from the pool. Second is, if there is no available page on the queue, > > > allocating from the page allocator. > > > > > > new_non_cma_page() can control allocation from the page allocator by > > > specifying correct gfp flag. However, dequeing cannot be controlled until > > > now, so, new_non_cma_page() skips dequeing completely. It is a suboptimal > > > since new_non_cma_page() cannot utilize hugetlb pages on the queue so this > > > patch tries to fix this situation. > > > > > > This patch makes the deque function on hugetlb CMA aware and skip CMA > > > pages if newly added skip_cma argument is passed as true. > > > > Hmm, can't you instead change dequeue_huge_page_node_exact() to test the PF_ > > flag and avoid adding bool skip_cma everywhere? > > Okay! Please check following patch. > > > > I think that's what Michal suggested [1] except he said "the code already does > > by memalloc_nocma_{save,restore} API". It needs extending a bit though, AFAICS. > > __gup_longterm_locked() indeed does the save/restore, but restore comes before > > check_and_migrate_cma_pages() and thus new_non_cma_page() is called, so an > > adjustment is needed there, but that's all? > > > > Hm the adjustment should be also done because save/restore is done around > > __get_user_pages_locked(), but check_and_migrate_cma_pages() also calls > > __get_user_pages_locked(), and that call not being between nocma save and > > restore is thus also a correctness issue? > > Simply, I call memalloc_nocma_{save,restore} in new_non_cma_page(). It > would not cause any problem. I believe a proper fix is the following. The scope is really defined for FOLL_LONGTERM pins and pushing it inside check_and_migrate_cma_pages will solve the problem as well but it imho makes more sense to do it in the caller the same way we do for any others. Fixes: 9a4e9f3b2d73 ("mm: update get_user_pages_longterm to migrate pages allocated from CMA region") I am not sure this is worth backporting to stable yet. diff --git a/mm/gup.c b/mm/gup.c index de9e36262ccb..75980dd5a2fc 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1794,7 +1794,6 @@ static long __gup_longterm_locked(struct task_struct *tsk, vmas_tmp, NULL, gup_flags); if (gup_flags & FOLL_LONGTERM) { - memalloc_nocma_restore(flags); if (rc < 0) goto out; @@ -1802,11 +1801,13 @@ static long __gup_longterm_locked(struct task_struct *tsk, for (i = 0; i < rc; i++) put_page(pages[i]); rc = -EOPNOTSUPP; + memalloc_nocma_restore(flags); goto out; } rc = check_and_migrate_cma_pages(tsk, mm, start, rc, pages, vmas_tmp, gup_flags); + memalloc_nocma_restore(flags); } out: -- Michal Hocko SUSE Labs