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[209.85.220.65]) by mx.google.com with SMTPS id k18sor2103097ede.0.2019.05.09.06.55.34 for (Google Transport Security); Thu, 09 May 2019 06:55:35 -0700 (PDT) Received-SPF: pass (google.com: domain of richard.weiyang@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=oQCvYs9j; spf=pass (google.com: domain of richard.weiyang@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=richard.weiyang@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com 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-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) 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: 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