From patchwork Fri Jan 14 22:09:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12714137 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 99639C433EF for ; Fri, 14 Jan 2022 22:09:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 299FA6B015F; Fri, 14 Jan 2022 17:09:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 248EB6B0161; Fri, 14 Jan 2022 17:09:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0EA666B0162; Fri, 14 Jan 2022 17:09:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id F2B196B015F for ; Fri, 14 Jan 2022 17:09:08 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id AD67180C7BF8 for ; Fri, 14 Jan 2022 22:09:08 +0000 (UTC) X-FDA: 79030283976.11.8B887D7 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf14.hostedemail.com (Postfix) with ESMTP id DDB7C10000E for ; Fri, 14 Jan 2022 22:09:07 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 661B8CE19A9; Fri, 14 Jan 2022 22:09:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40547C36AE5; Fri, 14 Jan 2022 22:09:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1642198143; bh=8YVev0luQKHfSKmGcdBlF001qT6IsletKbXz5bXpA98=; h=Date:From:To:Subject:In-Reply-To:From; b=OTRHQqQnj2pX4SESqTWgsFLqYHEdBltIPHwFXzIie3Heq/G62exfY+MRBEOYrwvsG EC/lF1M2vsixT54b/bb+TFw6I/HoJT4SUH+GIRRr5CBbx1U5CvYPfDrpa7IjAJ0v+k PiD1SxpFE1+y5EvYVzma2KgxGNPwVOIHO4QC0JOQ= Date: Fri, 14 Jan 2022 14:09:02 -0800 From: Andrew Morton To: akpm@linux-foundation.org, aneesh.kumar@linux.vnet.ibm.com, david@redhat.com, dinghui@sangfor.com.cn, linmiaohe@huawei.com, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, naoya.horiguchi@nec.com, osalvador@suse.de, peterx@redhat.com, shy828301@gmail.com, tony.luck@intel.com, torvalds@linux-foundation.org Subject: [patch 111/146] mm/hwpoison: mf_mutex for soft offline and unpoison Message-ID: <20220114220902.48bKohjgW%akpm@linux-foundation.org> In-Reply-To: <20220114140222.6b14f0061194d3200000c52d@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: DDB7C10000E X-Stat-Signature: pwfxk5oyua7fb3zsq8i6p6wsge7h4jjn Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=OTRHQqQn; dmarc=none; spf=pass (imf14.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam06 X-HE-Tag: 1642198147-628842 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Naoya Horiguchi Subject: mm/hwpoison: mf_mutex for soft offline and unpoison Patch series "mm/hwpoison: fix unpoison_memory()", v4. Main purpose of this series is to sync unpoison code to recent changes around how hwpoison code takes page refcount. Unpoison should work or simply fail (without crash) if impossible. The recent works of keeping hwpoison pages in shmem pagecache introduce a new state of hwpoisoned pages, but unpoison for such pages is not supported yet with this series. It seems that soft-offline and unpoison can be used as general purpose page offline/online mechanism (not in the context of memory error). I think that we need some additional works to realize it because currently soft-offline and unpoison are assumed not to happen so frequently (print out too many messages for aggressive usecases). But anyway this could be another interesting next topic. v1: https://lore.kernel.org/linux-mm/20210614021212.223326-1-nao.horiguchi@gmail.com/ v2: https://lore.kernel.org/linux-mm/20211025230503.2650970-1-naoya.horiguchi@linux.dev/ v3: https://lore.kernel.org/linux-mm/20211105055058.3152564-1-naoya.horiguchi@linux.dev/ This patch (of 3): Originally mf_mutex is introduced to serialize multiple MCE events, but it is not that useful to allow unpoison to run in parallel with memory_failure() and soft offline. So apply mf_mutex to soft offline and unpoison. The memory failure handler and soft offline handler get simpler with this. Link: https://lkml.kernel.org/r/20211115084006.3728254-1-naoya.horiguchi@linux.dev Link: https://lkml.kernel.org/r/20211115084006.3728254-2-naoya.horiguchi@linux.dev Signed-off-by: Naoya Horiguchi Reviewed-by: Yang Shi Cc: "Aneesh Kumar K.V" Cc: David Hildenbrand Cc: Ding Hui Cc: Miaohe Lin Cc: Michal Hocko Cc: Oscar Salvador Cc: Peter Xu Cc: Tony Luck Signed-off-by: Andrew Morton --- mm/memory-failure.c | 62 ++++++++++++------------------------------ 1 file changed, 18 insertions(+), 44 deletions(-) --- a/mm/memory-failure.c~mm-hwpoison-mf_mutex-for-soft-offline-and-unpoison +++ a/mm/memory-failure.c @@ -1502,14 +1502,6 @@ static int memory_failure_hugetlb(unsign lock_page(head); page_flags = head->flags; - if (!PageHWPoison(head)) { - pr_err("Memory failure: %#lx: just unpoisoned\n", pfn); - num_poisoned_pages_dec(); - unlock_page(head); - put_page(head); - return 0; - } - /* * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so * simply disable it. In order to make it work properly, we need @@ -1623,6 +1615,8 @@ out: return rc; } +static DEFINE_MUTEX(mf_mutex); + /** * memory_failure - Handle memory failure of a page. * @pfn: Page Number of the corrupted page @@ -1649,7 +1643,6 @@ int memory_failure(unsigned long pfn, in int res = 0; unsigned long page_flags; bool retry = true; - static DEFINE_MUTEX(mf_mutex); if (!sysctl_memory_failure_recovery) panic("Memory failure on page %lx", pfn); @@ -1783,16 +1776,6 @@ try_again: */ page_flags = p->flags; - /* - * unpoison always clear PG_hwpoison inside page lock - */ - if (!PageHWPoison(p)) { - pr_err("Memory failure: %#lx: just unpoisoned\n", pfn); - num_poisoned_pages_dec(); - unlock_page(p); - put_page(p); - goto unlock_mutex; - } if (hwpoison_filter(p)) { if (TestClearPageHWPoison(p)) num_poisoned_pages_dec(); @@ -1973,6 +1956,7 @@ int unpoison_memory(unsigned long pfn) struct page *page; struct page *p; int freeit = 0; + int ret = 0; unsigned long flags = 0; static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); @@ -1983,39 +1967,30 @@ int unpoison_memory(unsigned long pfn) p = pfn_to_page(pfn); page = compound_head(p); + mutex_lock(&mf_mutex); + if (!PageHWPoison(p)) { unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n", pfn, &unpoison_rs); - return 0; + goto unlock_mutex; } if (page_count(page) > 1) { unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n", pfn, &unpoison_rs); - return 0; + goto unlock_mutex; } if (page_mapped(page)) { unpoison_pr_info("Unpoison: Someone maps the hwpoison page %#lx\n", pfn, &unpoison_rs); - return 0; + goto unlock_mutex; } if (page_mapping(page)) { unpoison_pr_info("Unpoison: the hwpoison page has non-NULL mapping %#lx\n", pfn, &unpoison_rs); - return 0; - } - - /* - * unpoison_memory() can encounter thp only when the thp is being - * worked by memory_failure() and the page lock is not held yet. - * In such case, we yield to memory_failure() and make unpoison fail. - */ - if (!PageHuge(page) && PageTransHuge(page)) { - unpoison_pr_info("Unpoison: Memory failure is now running on %#lx\n", - pfn, &unpoison_rs); - return 0; + goto unlock_mutex; } if (!get_hwpoison_page(p, flags)) { @@ -2023,29 +1998,23 @@ int unpoison_memory(unsigned long pfn) num_poisoned_pages_dec(); unpoison_pr_info("Unpoison: Software-unpoisoned free page %#lx\n", pfn, &unpoison_rs); - return 0; + goto unlock_mutex; } - lock_page(page); - /* - * This test is racy because PG_hwpoison is set outside of page lock. - * That's acceptable because that won't trigger kernel panic. Instead, - * the PG_hwpoison page will be caught and isolated on the entrance to - * the free buddy page pool. - */ if (TestClearPageHWPoison(page)) { unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n", pfn, &unpoison_rs); num_poisoned_pages_dec(); freeit = 1; } - unlock_page(page); put_page(page); if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1)) put_page(page); - return 0; +unlock_mutex: + mutex_unlock(&mf_mutex); + return ret; } EXPORT_SYMBOL(unpoison_memory); @@ -2226,9 +2195,12 @@ int soft_offline_page(unsigned long pfn, return -EIO; } + mutex_lock(&mf_mutex); + if (PageHWPoison(page)) { pr_info("%s: %#lx page already poisoned\n", __func__, pfn); put_ref_page(ref_page); + mutex_unlock(&mf_mutex); return 0; } @@ -2247,5 +2219,7 @@ retry: } } + mutex_unlock(&mf_mutex); + return ret; }