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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 ED8E6C43381 for ; Wed, 10 Mar 2021 21:11:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCE4264FD6 for ; Wed, 10 Mar 2021 21:11:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233825AbhCJVLa (ORCPT ); Wed, 10 Mar 2021 16:11:30 -0500 Received: from mx2.suse.de ([195.135.220.15]:38774 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233809AbhCJVL0 (ORCPT ); Wed, 10 Mar 2021 16:11:26 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1615410684; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6GUjnkXjBs1KtZmnlih/UvqUZNGHdMWjAjgw8SoXP3g=; b=Gu5UZClhRbGMERTYbpCARsXtae9aRA04srw0EVXmmZO4aQTUCX2Zs0Qbr5Sr8+BDlzEj0G l8pGFJa4Vq116BU1/YmH0dqtEFV8fGdw+gKGqh6qXtdxuCdLWa3t6NgoSdAFaYQv3nzoWm 2XS2v3LzCrH+44JAXJFCIBCsMEkAoLU= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B550DAC8C; Wed, 10 Mar 2021 21:11:24 +0000 (UTC) Date: Wed, 10 Mar 2021 22:11:22 +0100 From: Michal Hocko To: Mike Kravetz Cc: Muchun Song , corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, osalvador@suse.de, song.bao.hua@hisilicon.com, david@redhat.com, naoya.horiguchi@nec.com, joao.m.martins@oracle.com, duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Chen Huang , Bodeddula Balasubramaniam Subject: Re: [PATCH v18 4/9] mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page Message-ID: References: <20210308102807.59745-1-songmuchun@bytedance.com> <20210308102807.59745-5-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 10-03-21 10:56:08, Mike Kravetz wrote: > On 3/10/21 7:19 AM, Michal Hocko wrote: > > On Mon 08-03-21 18:28:02, Muchun Song wrote: > > [...] > >> @@ -1447,7 +1486,7 @@ void free_huge_page(struct page *page) > >> /* > >> * Defer freeing if in non-task context to avoid hugetlb_lock deadlock. > >> */ > >> - if (!in_task()) { > >> + if (in_atomic()) { > > > > As I've said elsewhere in_atomic doesn't work for CONFIG_PREEMPT_COUNT=n. > > We need this change for other reasons and so it would be better to pull > > it out into a separate patch which also makes HUGETLB depend on > > PREEMPT_COUNT. > > Yes, the issue of calling put_page for hugetlb pages from any context > still needs work. IMO, that is outside the scope of this series. We > already have code in this path which blocks/sleeps. > > Making HUGETLB depend on PREEMPT_COUNT is too restrictive. IIUC, > PREEMPT_COUNT will only be enabled if we enable: > PREEMPT "Preemptible Kernel (Low-Latency Desktop)" > PREEMPT_RT "Fully Preemptible Kernel (Real-Time)" > or, other 'debug' options. These are not enabled in 'more common' > kernels. Of course, we do not want to disable HUGETLB in common > configurations. I haven't tried that but PREEMPT_COUNT should be selectable even without any change to the preemption model (e.g. !PREEMPT). -- Michal Hocko SUSE Labs