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 23899C433EF for ; Wed, 27 Apr 2022 07:11:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358622AbiD0HOu (ORCPT ); Wed, 27 Apr 2022 03:14:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358632AbiD0HOr (ORCPT ); Wed, 27 Apr 2022 03:14:47 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72BC43B00C for ; Wed, 27 Apr 2022 00:11:34 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Kp9022Tw8zhYKN; Wed, 27 Apr 2022 15:11:14 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 27 Apr 2022 15:11:32 +0800 Subject: Re: [RFC PATCH v1 1/4] mm, hwpoison, hugetlb: introduce SUBPAGE_INDEX_HWPOISON to save raw error page To: Naoya Horiguchi CC: Andrew Morton , David Hildenbrand , Mike Kravetz , Yang Shi , Oscar Salvador , Muchun Song , Naoya Horiguchi , , Linux-MM References: <20220427042841.678351-1-naoya.horiguchi@linux.dev> <20220427042841.678351-2-naoya.horiguchi@linux.dev> From: Miaohe Lin Message-ID: <5b956156-887b-1d91-7831-28a66db53c6a@huawei.com> Date: Wed, 27 Apr 2022 15:11:31 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220427042841.678351-2-naoya.horiguchi@linux.dev> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/4/27 12:28, Naoya Horiguchi wrote: > From: Naoya Horiguchi > > When handling memory error on a hugetlb page, the error handler tries to > dissolve and turn it into 4kB pages. If it's successfully dissolved, > PageHWPoison flag is moved to the raw error page, so but that's all s/so but/so/ > right. However, dissolve sometimes fails, then the error page is left > as hwpoisoned hugepage. It's useful if we can retry to dissolve it to > save healthy pages, but that's not possible now because the information > about where the raw error page is lost. > > Use the private field of a tail page to keep that information. The code Only one raw error page is saved now. Should this be ok? I think so as memory failure should be rare anyway? > path of shrinking hugepage pool used this info to try delayed dissolve. > > Signed-off-by: Naoya Horiguchi > --- > include/linux/hugetlb.h | 24 ++++++++++++++++++++++++ > mm/hugetlb.c | 9 +++++++++ > mm/memory-failure.c | 2 ++ > 3 files changed, 35 insertions(+) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index ac2a1d758a80..689e69cb556b 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -42,6 +42,9 @@ enum { > SUBPAGE_INDEX_CGROUP, /* reuse page->private */ > SUBPAGE_INDEX_CGROUP_RSVD, /* reuse page->private */ > __MAX_CGROUP_SUBPAGE_INDEX = SUBPAGE_INDEX_CGROUP_RSVD, > +#endif > +#ifdef CONFIG_CGROUP_HUGETLB > + SUBPAGE_INDEX_HWPOISON, > #endif Do we rely on the CONFIG_CGROUP_HUGETLB to store the raw error page? > __NR_USED_SUBPAGE, > }; > @@ -784,6 +787,27 @@ extern int dissolve_free_huge_page(struct page *page); > extern int dissolve_free_huge_pages(unsigned long start_pfn, > unsigned long end_pfn); > > +#ifdef CONFIG_MEMORY_FAILURE > +/* > + * pointer to raw error page is located in hpage[SUBPAGE_INDEX_HWPOISON].private > + */ > +static inline struct page *hugetlb_page_hwpoison(struct page *hpage) > +{ > + return (void *)page_private(hpage + SUBPAGE_INDEX_HWPOISON); > +} > + > +static inline void hugetlb_set_page_hwpoison(struct page *hpage, > + struct page *page) > +{ > + set_page_private(hpage + SUBPAGE_INDEX_HWPOISON, (unsigned long)page); > +} > +#else > +static inline struct page *hugetlb_page_hwpoison(struct page *hpage) > +{ > + return NULL; > +} > +#endif > + > #ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION > #ifndef arch_hugetlb_migration_supported > static inline bool arch_hugetlb_migration_supported(struct hstate *h) > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index f8e048b939c7..6867ea8345d1 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1547,6 +1547,15 @@ static void __update_and_free_page(struct hstate *h, struct page *page) > return; > } > > + if (unlikely(PageHWPoison(page))) { > + struct page *raw_error = hugetlb_page_hwpoison(page); > + > + if (raw_error && raw_error != page) { > + SetPageHWPoison(raw_error); > + ClearPageHWPoison(page); > + } > + } > + > for (i = 0; i < pages_per_huge_page(h); > i++, subpage = mem_map_next(subpage, page, i)) { > subpage->flags &= ~(1 << PG_locked | 1 << PG_error | > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 3e36fc19c4d1..73948a00ad4a 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1535,6 +1535,8 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > goto out; > } > > + hugetlb_set_page_hwpoison(head, page); > + > return ret; > out: > if (count_increased) > This patch looks good to me. I will learn this series more when I get more time. Many thanks for your hard work! :)