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 0EB23C433FE for ; Sat, 15 Oct 2022 01:58:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229555AbiJOB6T (ORCPT ); Fri, 14 Oct 2022 21:58:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229470AbiJOB6P (ORCPT ); Fri, 14 Oct 2022 21:58:15 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D245781685 for ; Fri, 14 Oct 2022 18:58:12 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Mq5rh0FyczVj74; Sat, 15 Oct 2022 09:53:40 +0800 (CST) Received: from [10.174.151.185] (10.174.151.185) 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 15.1.2375.31; Sat, 15 Oct 2022 09:58:10 +0800 Subject: Re: [PATCH v6 1/4] mm,hwpoison,hugetlb,memory_hotplug: hotremove memory section with hwpoisoned hugepage To: Naoya Horiguchi , CC: Andrew Morton , David Hildenbrand , Mike Kravetz , Yang Shi , Oscar Salvador , Muchun Song , Jane Chu , Naoya Horiguchi , References: <20221007010706.2916472-1-naoya.horiguchi@linux.dev> <20221007010706.2916472-2-naoya.horiguchi@linux.dev> From: Miaohe Lin Message-ID: Date: Sat, 15 Oct 2022 09:58:09 +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: <20221007010706.2916472-2-naoya.horiguchi@linux.dev> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.151.185] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) 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 2022/10/7 9:07, Naoya Horiguchi wrote: > From: Naoya Horiguchi > > HWPoisoned page is not supposed to be accessed once marked, but currently > such accesses can happen during memory hotremove because do_migrate_range() > can be called before dissolve_free_huge_pages() is called. > > Clear HPageMigratable for hwpoisoned hugepages to prevent them from being > migrated. This should be done in hugetlb_lock to avoid race against > isolate_hugetlb(). > > get_hwpoison_huge_page() needs to have a flag to show it's called from > unpoison to take refcount of hwpoisoned hugepages, so add it. > > Reported-by: Miaohe Lin > Signed-off-by: Naoya Horiguchi Sorry for late respond. I was spending a busy week. :) And thanks for your work, Naoya. > --- > ChangeLog v3 -> v6: > - introduce migratable_cleared to remember that HPageMigratable is > cleared in error handling. It's needed to cancel when an error event > is filtered by hwpoison_filter(). (Thanks to Miaohe) > > ChangeLog v2 -> v3 > - move to the approach of clearing HPageMigratable instead of shifting > dissolve_free_huge_pages. > --- > include/linux/hugetlb.h | 10 ++++++---- > include/linux/mm.h | 6 ++++-- > mm/hugetlb.c | 9 +++++---- > mm/memory-failure.c | 21 +++++++++++++++++---- > 4 files changed, 32 insertions(+), 14 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 32d45e96a894..19b99ff7fea0 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -183,8 +183,9 @@ bool hugetlb_reserve_pages(struct inode *inode, long from, long to, > long hugetlb_unreserve_pages(struct inode *inode, long start, long end, > long freed); > int isolate_hugetlb(struct page *page, struct list_head *list); > -int get_hwpoison_huge_page(struct page *page, bool *hugetlb); > -int get_huge_page_for_hwpoison(unsigned long pfn, int flags); > +int get_hwpoison_huge_page(struct page *page, bool *hugetlb, bool unpoison); > +int get_huge_page_for_hwpoison(unsigned long pfn, int flags, > + bool *migratable_cleared); > void putback_active_hugepage(struct page *page); > void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason); > void free_huge_page(struct page *page); > @@ -391,12 +392,13 @@ static inline int isolate_hugetlb(struct page *page, struct list_head *list) > return -EBUSY; > } > > -static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb) > +static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb, bool unpoison) > { > return 0; > } > > -static inline int get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +static inline int get_huge_page_for_hwpoison(unsigned long pfn, int flags, > + bool *migratable_cleared) > { > return 0; > } > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8bbcccbc5565..3264bf993ad8 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3277,9 +3277,11 @@ extern void shake_page(struct page *p); > extern atomic_long_t num_poisoned_pages __read_mostly; > extern int soft_offline_page(unsigned long pfn, int flags); > #ifdef CONFIG_MEMORY_FAILURE > -extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags); > +extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags, > + bool *migratable_cleared); > #else > -static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags, > + bool *migratable_cleared) > { > return 0; > } > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 63fe47a0240a..0e482dfaf92e 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -7253,7 +7253,7 @@ int isolate_hugetlb(struct page *page, struct list_head *list) > return ret; > } > > -int get_hwpoison_huge_page(struct page *page, bool *hugetlb) > +int get_hwpoison_huge_page(struct page *page, bool *hugetlb, bool unpoison) > { > int ret = 0; > > @@ -7263,7 +7263,7 @@ int get_hwpoison_huge_page(struct page *page, bool *hugetlb) > *hugetlb = true; > if (HPageFreed(page)) > ret = 0; > - else if (HPageMigratable(page)) > + else if (HPageMigratable(page) || unpoison) > ret = get_page_unless_zero(page); > else > ret = -EBUSY; > @@ -7272,12 +7272,13 @@ int get_hwpoison_huge_page(struct page *page, bool *hugetlb) > return ret; > } > > -int get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +int get_huge_page_for_hwpoison(unsigned long pfn, int flags, > + bool *migratable_cleared) > { > int ret; > > spin_lock_irq(&hugetlb_lock); > - ret = __get_huge_page_for_hwpoison(pfn, flags); > + ret = __get_huge_page_for_hwpoison(pfn, flags, migratable_cleared); > spin_unlock_irq(&hugetlb_lock); > return ret; > } > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 145bb561ddb3..d4fef56c0438 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1244,7 +1244,7 @@ static int __get_hwpoison_page(struct page *page, unsigned long flags) > int ret = 0; > bool hugetlb = false; > > - ret = get_hwpoison_huge_page(head, &hugetlb); > + ret = get_hwpoison_huge_page(head, &hugetlb, false); > if (hugetlb) > return ret; > > @@ -1334,7 +1334,7 @@ static int __get_unpoison_page(struct page *page) > int ret = 0; > bool hugetlb = false; > > - ret = get_hwpoison_huge_page(head, &hugetlb); > + ret = get_hwpoison_huge_page(head, &hugetlb, true); > if (hugetlb) > return ret; > > @@ -1785,7 +1785,8 @@ void hugetlb_clear_page_hwpoison(struct page *hpage) > * -EBUSY - the hugepage is busy (try to retry) > * -EHWPOISON - the hugepage is already hwpoisoned > */ > -int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +int __get_huge_page_for_hwpoison(unsigned long pfn, int flags, > + bool *migratable_cleared) > { > struct page *page = pfn_to_page(pfn); > struct page *head = compound_head(page); > @@ -1815,6 +1816,15 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > goto out; > } > > + /* > + * Clearing HPageMigratable for hwpoisoned hugepages to prevent them > + * from being migrated by memory hotremove. > + */ > + if (count_increased) { > + *migratable_cleared = true; > + ClearHPageMigratable(head); I think I might be nitpicking... But it seems ClearHPageMigratable is not enough here. 1. In MF_COUNT_INCREASED case, we don't know whether HPageMigratable is set. 2. Even if HPageMigratable is set, there might be a race window before we clear HPageMigratable? So "*migratable_cleared = TestClearHPageMigratable" might be better? But I might be wrong. With above fixed (if it's really a problem), this patch looks good to me. Reviewed-by: Miaohe Lin Thanks, Miaohe Lin