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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 3B509C433DB for ; Mon, 22 Feb 2021 10:52:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E2C7564E5C for ; Mon, 22 Feb 2021 10:52:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230310AbhBVKvq (ORCPT ); Mon, 22 Feb 2021 05:51:46 -0500 Received: from mx2.suse.de ([195.135.220.15]:45744 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230270AbhBVKvo (ORCPT ); Mon, 22 Feb 2021 05:51:44 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5B719AFE1; Mon, 22 Feb 2021 10:51:02 +0000 (UTC) Date: Mon, 22 Feb 2021 11:50:56 +0100 From: Oscar Salvador To: Muchun Song Cc: Michal Hocko , Jonathan Corbet , Mike Kravetz , Thomas Gleixner , mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, Peter Zijlstra , viro@zeniv.linux.org.uk, Andrew Morton , paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, Randy Dunlap , oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, Mina Almasry , David Rientjes , Matthew Wilcox , "Song Bao Hua (Barry Song)" , David Hildenbrand , HORIGUCHI =?utf-8?B?TkFPWUEo5aCA5Y+jIOebtOS5nyk=?= , Joao Martins , Xiongchun duan , linux-doc@vger.kernel.org, LKML , Linux Memory Management List , linux-fsdevel Subject: Re: [External] Re: [PATCH v16 4/9] mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page Message-ID: <20210222105051.GA23063@linux> References: <20210219104954.67390-1-songmuchun@bytedance.com> <20210219104954.67390-5-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Feb 22, 2021 at 06:31:12PM +0800, Muchun Song wrote: > On Mon, Feb 22, 2021 at 5:25 PM Michal Hocko wrote: > > > > On Sat 20-02-21 12:20:36, Muchun Song wrote: > > > On Fri, Feb 19, 2021 at 10:12 PM Michal Hocko wrote: > > [...] > > > > What about hugetlb page poisoning on HW failure (resp. soft offlining)? > > > > > > If the HW poisoned hugetlb page failed to be dissolved, the page > > > will go back to the free list with PG_HWPoison set. But the page > > > will not be used, because we will check whether the page is HW > > > poisoned when it is dequeued from the free list. If so, we will skip > > > this page. Not really. If the huge page is dissolved, we will take the page out of the the freelist. See take_page_off_buddy in memory_failure_hugetlb. In an ideal world, we should inspect that page in free_pages_prepare(), remove the HPWpoisoned page and process the others, without letting that page hit Buddy. And not only for hugetlb, but for any higher order page. See how memory_failure() happily disengage itself when it finds a higher order page. It does it because we have the premise that once that page hits Buddy, it will stay there as the check_new_page guards us. But this has been proofed to be quite a weak measure, as compaction does not performs such a check, and so the page can sneak in. I fixed that for soft-offline, and for memory-failure in some cases, but more needs to be done and is it in my TODO list. > > Can this lead to an under provisioned pool then? Or is there a new > > hugetlb allocated to replace the poisoned one? > > Actually, no page will be allocated. Your concern is right. But without > this patch, the result does not change. e.g. The HW poisoned page > can fail to be dissolved when h->free_huge_pages is equal to > h->resv_huge_pages. But no one seems to have reported this issue so > far. Maybe this behavior needs improvement in the feature. Yes, something to improve. I shall have a look. -- Oscar Salvador SUSE L3