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=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 E41BAC04AB3 for ; Thu, 9 May 2019 13:55:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B15E02089E for ; Thu, 9 May 2019 13:55:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="oQCvYs9j" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726730AbfEINzh (ORCPT ); Thu, 9 May 2019 09:55:37 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:41816 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbfEINzh (ORCPT ); Thu, 9 May 2019 09:55:37 -0400 Received: by mail-ed1-f66.google.com with SMTP id m4so2107131edd.8; Thu, 09 May 2019 06:55:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=rj8sR0p1Edqa94H02tBjaXnEUtoaRjwEJVzZPumNj1g=; b=oQCvYs9jZqA0mKZRzCMWu05oFj2Zz17/PVNd4bwpPPpxmMr0K+ZQCs7yxqlPtfjuMy 8OjUA2czA5H6SB9uPKPi/jS92gskpNjvYeYP/Q4yo9+o9Xrd9/e5lEK5NKwBomh3Cy8d txu9rR8KNjutQFiKex2oKNITF45PZElb82I9QA/6KUxfMCLsrY1lDcu5LtawuUioBTcj C363GL59Zdaxz2o8wF08BTrzO41fdEKqPgs6o4QzXc1PYVqQv9UpbOEWVkNzzqcmKdVj 852r0xVwgC3ApDh6OJFtIWvfw2X6OVJBAUv3KUKUNUdncpeZkAmD/cq2XxXLjQEZfw5F hPxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=rj8sR0p1Edqa94H02tBjaXnEUtoaRjwEJVzZPumNj1g=; b=FuxIhKCyoP/mbxqCoMMNNVHiTYFRLY6GeGczcDgWkaMrhAo4/IM96TTtJtJiR/jR5O x3AGXBl42VneTXnGLSEB0o4/Ade9YqNqDYyJyH//xncwf+2pyxsv47IaP/22/sbZs403 lSTdGYvZrl8j8AILwnGfetf2fLjgKqiHo20AFYGtXl56pGwWsWCg2l8CUXIvPI3yuBM3 F4SX/1CdlAJeHn5TBQ0RxN/8D8JtK3OnctkU5l6p+t957XgnxXWqfMOyvRM5LsXhpYV6 MwE1fR8YJWSHUOZEVSlIR24yJIl9ARLU6L+1oPBsH60gl+BwyLldEnIMGouQJpX7LjmK 7BNQ== X-Gm-Message-State: APjAAAVmgkQWbBZcBGVqIZNh5g3+KkWJfHuJpQbAc0FunZsOxmDIOtlb ciQzYEVcUke/lt+WBOEdaSc= X-Google-Smtp-Source: APXvYqyqamcbXYaLythnIDnP0cKrQ7Jqxn1LlTAxYUXRdkLE65y8UJdLAseURDgvrzBfIKf7YsPB9w== X-Received: by 2002:a50:a5b4:: with SMTP id a49mr4299981edc.30.1557410134597; Thu, 09 May 2019 06:55:34 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id j55sm611135ede.27.2019.05.09.06.55.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 09 May 2019 06:55:33 -0700 (PDT) Date: Thu, 9 May 2019 13:55:33 +0000 From: Wei Yang To: David Hildenbrand Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, akpm@linux-foundation.org, Dan Williams , Greg Kroah-Hartman , "Rafael J. Wysocki" , "mike.travis@hpe.com" , Ingo Molnar , Andrew Banman , Oscar Salvador , Michal Hocko , Pavel Tatashin , Qian Cai , Wei Yang , Arun KS , Mathieu Malaterre Subject: Re: [PATCH v2 4/8] mm/memory_hotplug: Create memory block devices after arch_add_memory() Message-ID: <20190509135533.6xok3v7rxxaohc77@master> Reply-To: Wei Yang References: <20190507183804.5512-1-david@redhat.com> <20190507183804.5512-5-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190507183804.5512-5-david@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 07, 2019 at 08:38:00PM +0200, David Hildenbrand wrote: >Only memory to be added to the buddy and to be onlined/offlined by >user space using memory block devices needs (and should have!) memory >block devices. > >Factor out creation of memory block devices Create all devices after >arch_add_memory() succeeded. We can later drop the want_memblock parameter, >because it is now effectively stale. > >Only after memory block devices have been added, memory can be onlined >by user space. This implies, that memory is not visible to user space at >all before arch_add_memory() succeeded. > >Cc: Greg Kroah-Hartman >Cc: "Rafael J. Wysocki" >Cc: David Hildenbrand >Cc: "mike.travis@hpe.com" >Cc: Andrew Morton >Cc: Ingo Molnar >Cc: Andrew Banman >Cc: Oscar Salvador >Cc: Michal Hocko >Cc: Pavel Tatashin >Cc: Qian Cai >Cc: Wei Yang >Cc: Arun KS >Cc: Mathieu Malaterre >Signed-off-by: David Hildenbrand >--- > drivers/base/memory.c | 70 ++++++++++++++++++++++++++---------------- > include/linux/memory.h | 2 +- > mm/memory_hotplug.c | 15 ++++----- > 3 files changed, 53 insertions(+), 34 deletions(-) > >diff --git a/drivers/base/memory.c b/drivers/base/memory.c >index 6e0cb4fda179..862c202a18ca 100644 >--- a/drivers/base/memory.c >+++ b/drivers/base/memory.c >@@ -701,44 +701,62 @@ static int add_memory_block(int base_section_nr) > return 0; > } > >+static void unregister_memory(struct memory_block *memory) >+{ >+ BUG_ON(memory->dev.bus != &memory_subsys); >+ >+ /* drop the ref. we got via find_memory_block() */ >+ put_device(&memory->dev); >+ device_unregister(&memory->dev); >+} >+ > /* >- * need an interface for the VM to add new memory regions, >- * but without onlining it. >+ * Create memory block devices for the given memory area. Start and size >+ * have to be aligned to memory block granularity. Memory block devices >+ * will be initialized as offline. > */ >-int hotplug_memory_register(int nid, struct mem_section *section) >+int hotplug_memory_register(unsigned long start, unsigned long size) > { >- int ret = 0; >+ unsigned long block_nr_pages = memory_block_size_bytes() >> PAGE_SHIFT; >+ unsigned long start_pfn = PFN_DOWN(start); >+ unsigned long end_pfn = start_pfn + (size >> PAGE_SHIFT); >+ unsigned long pfn; > struct memory_block *mem; >+ int ret = 0; > >- mutex_lock(&mem_sysfs_mutex); >+ BUG_ON(!IS_ALIGNED(start, memory_block_size_bytes())); >+ BUG_ON(!IS_ALIGNED(size, memory_block_size_bytes())); > >- mem = find_memory_block(section); >- if (mem) { >- mem->section_count++; >- put_device(&mem->dev); >- } else { >- ret = init_memory_block(&mem, section, MEM_OFFLINE); >+ mutex_lock(&mem_sysfs_mutex); >+ for (pfn = start_pfn; pfn != end_pfn; pfn += block_nr_pages) { >+ mem = find_memory_block(__pfn_to_section(pfn)); >+ if (mem) { >+ WARN_ON_ONCE(false); One question here, the purpose of WARN_ON_ONCE(false) is? Would we trigger this? >+ put_device(&mem->dev); >+ continue; >+ } >+ ret = init_memory_block(&mem, __pfn_to_section(pfn), >+ MEM_OFFLINE); > if (ret) >- goto out; >- mem->section_count++; >+ break; >+ mem->section_count = memory_block_size_bytes() / >+ MIN_MEMORY_BLOCK_SIZE; Maybe we can leverage sections_per_block variable. mem->section_count = sections_per_block; >+ } >+ if (ret) { >+ end_pfn = pfn; >+ for (pfn = start_pfn; pfn != end_pfn; pfn += block_nr_pages) { >+ mem = find_memory_block(__pfn_to_section(pfn)); >+ if (!mem) >+ continue; >+ mem->section_count = 0; >+ unregister_memory(mem); >+ } > } -- Wei Yang Help you, Help me