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=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 BFAABC2B9F4 for ; Fri, 25 Jun 2021 06:08:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A0A65613B9 for ; Fri, 25 Jun 2021 06:08:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233157AbhFYGKx (ORCPT ); Fri, 25 Jun 2021 02:10:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:59648 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230192AbhFYGKw (ORCPT ); Fri, 25 Jun 2021 02:10:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624601311; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UtxZ0EJDwdcCMvCNH9EVJ4BJyKK4v0Z5I/IrQpjJgpY=; b=XCeUH6WUtovdCXjGkIYNowfj/SYGVMK+0b1ail6NEm4pLEn60QbCN2JJ1Sr9yNYzQUmE9h s93T/5BiWTynrbRckSd5fahmgQos9uIolPiyGxrTQC/656sIKecwckEZVLWeqJSclKkADC dGyvjRukpDut1kMH7dJgVBlRzV1V0nM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-52-LOt0lbSiMOGbobY68_uarA-1; Fri, 25 Jun 2021 02:08:27 -0400 X-MC-Unique: LOt0lbSiMOGbobY68_uarA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 819521084F4C; Fri, 25 Jun 2021 06:08:26 +0000 (UTC) Received: from [10.64.54.233] (vpn2-54-233.bne.redhat.com [10.64.54.233]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B8D3A60622; Fri, 25 Jun 2021 06:08:15 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH v4 2/4] mm/page_reporting: Export reporting order as module parameter To: "Michael S. Tsirkin" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, alexander.duyck@gmail.com, david@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, catalin.marinas@arm.com, will@kernel.org, shan.gavin@gmail.com References: <20210625014710.42954-1-gshan@redhat.com> <20210625014710.42954-3-gshan@redhat.com> <20210625014928-mutt-send-email-mst@kernel.org> From: Gavin Shan Message-ID: Date: Fri, 25 Jun 2021 16:08:13 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <20210625014928-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/25/21 3:53 PM, Michael S. Tsirkin wrote: > On Fri, Jun 25, 2021 at 09:47:08AM +0800, Gavin Shan wrote: >> The macro PAGE_REPORTING_MIN_ORDER is defined as the page reporting >> threshold. It can't be adjusted at runtime. >> >> This introduces a variable (@page_reporting_order) to replace the >> marcro (PAGE_REPORTING_MIN_ORDER). MAX_ORDER is assigned to it initially, >> meaning the page reporting is disabled. It will be specified by driver >> if valid one is provided. Otherwise, it will fall back to @pageblock_order. >> It's also exported so that the page reporting order can be adjusted at >> runtime. >> >> Suggested-by: David Hildenbrand >> Signed-off-by: Gavin Shan >> Reviewed-by: Alexander Duyck >> --- >> Documentation/admin-guide/kernel-parameters.txt | 6 ++++++ >> mm/page_reporting.c | 9 +++++++-- >> mm/page_reporting.h | 5 ++--- >> 3 files changed, 15 insertions(+), 5 deletions(-) >> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index cb89dbdedc46..566c4b9af3cd 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -3566,6 +3566,12 @@ >> off: turn off poisoning (default) >> on: turn on poisoning >> >> + page_reporting.page_reporting_order= >> + [KNL] Minimal page reporting order >> + Format: >> + Adjust the minimal page reporting order. The page >> + reporting is disabled when it exceeds (MAX_ORDER-1). > > Which the admin knows how? Run grep in the kernel source? > Well, I guess it's fine as it's used for debugging purpose. I guess it's mostly used by developers. Also, the value can be changed by the module parameter in "/sys/module/page_reporting" either. >> + >> panic= [KNL] Kernel behaviour on panic: delay >> timeout > 0: seconds before rebooting >> timeout = 0: wait forever >> diff --git a/mm/page_reporting.c b/mm/page_reporting.c >> index df9c5054e1b4..34bf4d26c2c4 100644 >> --- a/mm/page_reporting.c >> +++ b/mm/page_reporting.c >> @@ -4,12 +4,17 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> >> #include "page_reporting.h" >> #include "internal.h" >> >> +unsigned int page_reporting_order = MAX_ORDER; >> +module_param(page_reporting_order, uint, 0644); >> +MODULE_PARM_DESC(page_reporting_order, "Set page reporting order"); >> + >> #define PAGE_REPORTING_DELAY (2 * HZ) >> static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly; >> >> @@ -229,7 +234,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev, >> >> /* Generate minimum watermark to be able to guarantee progress */ >> watermark = low_wmark_pages(zone) + >> - (PAGE_REPORTING_CAPACITY << PAGE_REPORTING_MIN_ORDER); >> + (PAGE_REPORTING_CAPACITY << page_reporting_order); > > > Looks like this makes it easy to trigger undefined behaviour. Just use > any value > 31. > This function won't be run if page_reporting_order is more than (MAX_ORDER-1). >> >> /* >> * Cancel request if insufficient free memory or if we failed >> @@ -239,7 +244,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev, >> return err; >> >> /* Process each free list starting from lowest order/mt */ >> - for (order = PAGE_REPORTING_MIN_ORDER; order < MAX_ORDER; order++) { >> + for (order = page_reporting_order; order < MAX_ORDER; order++) { >> for (mt = 0; mt < MIGRATE_TYPES; mt++) { >> /* We do not pull pages from the isolate free list */ >> if (is_migrate_isolate(mt)) >> diff --git a/mm/page_reporting.h b/mm/page_reporting.h >> index 2c385dd4ddbd..c51dbc228b94 100644 >> --- a/mm/page_reporting.h >> +++ b/mm/page_reporting.h >> @@ -10,10 +10,9 @@ >> #include >> #include >> >> -#define PAGE_REPORTING_MIN_ORDER pageblock_order >> - >> #ifdef CONFIG_PAGE_REPORTING >> DECLARE_STATIC_KEY_FALSE(page_reporting_enabled); >> +extern unsigned int page_reporting_order; >> void __page_reporting_notify(void); >> >> static inline bool page_reported(struct page *page) >> @@ -38,7 +37,7 @@ static inline void page_reporting_notify_free(unsigned int order) >> return; >> >> /* Determine if we have crossed reporting threshold */ >> - if (order < PAGE_REPORTING_MIN_ORDER) >> + if (order < page_reporting_order) >> return; >> >> /* This will add a few cycles, but should be called infrequently */ >> -- >> 2.23.0 > Thanks, Gavin