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=-4.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_DBL_ABUSE_MALW,USER_AGENT_GIT autolearn=no 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 7CB45C2D0DB for ; Tue, 28 Jan 2020 14:30:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B4DB2469D for ; Tue, 28 Jan 2020 14:30:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580221816; bh=6+sIeDCWL98kM1rSX+iQdcZOPtQDuFTgs2Qm7V7R0Jk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=oQhrqSMCBJ2wse1HdeGpm1uLL96SHlJael2JS07vpLaGxaIJqxwFFjLkJ0rWxHBrV bMTIK3Jlvb/iQ6NwfQNwE84mO4OherBnBfuIGHiwUCzh764TvtV50UFuIk9UiK3ndg MGrZKfx+UZGHGj9BbYPJwn5rHtuLc8j0Q0fJoCl4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387716AbgA1OaP (ORCPT ); Tue, 28 Jan 2020 09:30:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:59874 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729012AbgA1OaO (ORCPT ); Tue, 28 Jan 2020 09:30:14 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4118D24692; Tue, 28 Jan 2020 14:30:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580221812; bh=6+sIeDCWL98kM1rSX+iQdcZOPtQDuFTgs2Qm7V7R0Jk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QMPzbNaGiDxTNs78peVZ7m+tLuwDCGu5PLzwcSIENvBmy/JgZ73pcw/A77eTdx35u r8W4EQhd824l/Qb792rAFrCMjMvjJ5hnSaZS0Ento4FZmYEPkabP7v2KkV/2mh7grH BB2+5Tk+s9GslxXTNZcLBye7HyqvF1lyH1vvLx+k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , David Hildenbrand , Masayoshi Mizuma , Tang Chen , "Rafael J. Wysocki" , Keith Busch , Jiri Olsa , "Peter Zijlstra (Intel)" , Jani Nikula , Nayna Jain , Michal Hocko , Oscar Salvador , Stephen Rothwell , Dan Williams , Pavel Tatashin , Andrew Morton , Linus Torvalds Subject: [PATCH 4.19 91/92] mm/memory_hotplug: fix try_offline_node() Date: Tue, 28 Jan 2020 15:08:59 +0100 Message-Id: <20200128135821.195654439@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200128135809.344954797@linuxfoundation.org> References: <20200128135809.344954797@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Hildenbrand commit 2c91f8fc6c999fe10185d8ad99fda1759f662f70 upstream. -- snip -- Only contextual issues: - Unrelated check_and_unmap_cpu_on_node() changes are missing. - Unrelated walk_memory_blocks() has not been moved/refactored yet. -- snip -- try_offline_node() is pretty much broken right now: - The node span is updated when onlining memory, not when adding it. We ignore memory that was mever onlined. Bad. - We touch possible garbage memmaps. The pfn_to_nid(pfn) can easily trigger a kernel panic. Bad for memory that is offline but also bad for subsection hotadd with ZONE_DEVICE, whereby the memmap of the first PFN of a section might contain garbage. - Sections belonging to mixed nodes are not properly considered. As memory blocks might belong to multiple nodes, we would have to walk all pageblocks (or at least subsections) within present sections. However, we don't have a way to identify whether a memmap that is not online was initialized (relevant for ZONE_DEVICE). This makes things more complicated. Luckily, we can piggy pack on the node span and the nid stored in memory blocks. Currently, the node span is grown when calling move_pfn_range_to_zone() - e.g., when onlining memory, and shrunk when removing memory, before calling try_offline_node(). Sysfs links are created via link_mem_sections(), e.g., during boot or when adding memory. If the node still spans memory or if any memory block belongs to the nid, we don't set the node offline. As memory blocks that span multiple nodes cannot get offlined, the nid stored in memory blocks is reliable enough (for such online memory blocks, the node still spans the memory). Introduce for_each_memory_block() to efficiently walk all memory blocks. Note: We will soon stop shrinking the ZONE_DEVICE zone and the node span when removing ZONE_DEVICE memory to fix similar issues (access of garbage memmaps) - until we have a reliable way to identify whether these memmaps were properly initialized. This implies later, that once a node had ZONE_DEVICE memory, we won't be able to set a node offline - which should be acceptable. Since commit f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") memory that is added is not assoziated with a zone/node (memmap not initialized). The introducing commit 60a5a19e7419 ("memory-hotplug: remove sysfs file of node") already missed that we could have multiple nodes for a section and that the zone/node span is updated when onlining pages, not when adding them. I tested this by hotplugging two DIMMs to a memory-less and cpu-less NUMA node. The node is properly onlined when adding the DIMMs. When removing the DIMMs, the node is properly offlined. Masayoshi Mizuma reported: : Without this patch, memory hotplug fails as panic: : : BUG: kernel NULL pointer dereference, address: 0000000000000000 : ... : Call Trace: : remove_memory_block_devices+0x81/0xc0 : try_remove_memory+0xb4/0x130 : __remove_memory+0xa/0x20 : acpi_memory_device_remove+0x84/0x100 : acpi_bus_trim+0x57/0x90 : acpi_bus_trim+0x2e/0x90 : acpi_device_hotplug+0x2b2/0x4d0 : acpi_hotplug_work_fn+0x1a/0x30 : process_one_work+0x171/0x380 : worker_thread+0x49/0x3f0 : kthread+0xf8/0x130 : ret_from_fork+0x35/0x40 [david@redhat.com: v3] Link: http://lkml.kernel.org/r/20191102120221.7553-1-david@redhat.com Link: http://lkml.kernel.org/r/20191028105458.28320-1-david@redhat.com Fixes: 60a5a19e7419 ("memory-hotplug: remove sysfs file of node") Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") # visiable after d0dc12e86b319 Signed-off-by: David Hildenbrand Tested-by: Masayoshi Mizuma Cc: Tang Chen Cc: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" Cc: Keith Busch Cc: Jiri Olsa Cc: "Peter Zijlstra (Intel)" Cc: Jani Nikula Cc: Nayna Jain Cc: Michal Hocko Cc: Oscar Salvador Cc: Stephen Rothwell Cc: Dan Williams Cc: Pavel Tatashin Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: David Hildenbrand Signed-off-by: Greg Kroah-Hartman --- drivers/base/memory.c | 36 ++++++++++++++++++++++++++++++++++++ include/linux/memory.h | 2 ++ mm/memory_hotplug.c | 47 +++++++++++++++++++++++++++++------------------ 3 files changed, 67 insertions(+), 18 deletions(-) --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -862,3 +862,39 @@ out: printk(KERN_ERR "%s() failed: %d\n", __func__, ret); return ret; } + +struct for_each_memory_block_cb_data { + walk_memory_blocks_func_t func; + void *arg; +}; + +static int for_each_memory_block_cb(struct device *dev, void *data) +{ + struct memory_block *mem = to_memory_block(dev); + struct for_each_memory_block_cb_data *cb_data = data; + + return cb_data->func(mem, cb_data->arg); +} + +/** + * for_each_memory_block - walk through all present memory blocks + * + * @arg: argument passed to func + * @func: callback for each memory block walked + * + * This function walks through all present memory blocks, calling func on + * each memory block. + * + * In case func() returns an error, walking is aborted and the error is + * returned. + */ +int for_each_memory_block(void *arg, walk_memory_blocks_func_t func) +{ + struct for_each_memory_block_cb_data cb_data = { + .func = func, + .arg = arg, + }; + + return bus_for_each_dev(&memory_subsys, NULL, &cb_data, + for_each_memory_block_cb); +} --- a/include/linux/memory.h +++ b/include/linux/memory.h @@ -119,6 +119,8 @@ extern int memory_isolate_notify(unsigne extern struct memory_block *find_memory_block_hinted(struct mem_section *, struct memory_block *); extern struct memory_block *find_memory_block(struct mem_section *); +typedef int (*walk_memory_blocks_func_t)(struct memory_block *, void *); +extern int for_each_memory_block(void *arg, walk_memory_blocks_func_t func); #define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<nid == nid ? -EEXIST : 0; +} + /** * try_offline_node * @nid: the node ID @@ -1824,25 +1836,24 @@ static int check_and_unmap_cpu_on_node(p void try_offline_node(int nid) { pg_data_t *pgdat = NODE_DATA(nid); - unsigned long start_pfn = pgdat->node_start_pfn; - unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages; - unsigned long pfn; - - for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { - unsigned long section_nr = pfn_to_section_nr(pfn); - - if (!present_section_nr(section_nr)) - continue; - - if (pfn_to_nid(pfn) != nid) - continue; - - /* - * some memory sections of this node are not removed, and we - * can't offline node now. - */ + int rc; + + /* + * If the node still spans pages (especially ZONE_DEVICE), don't + * offline it. A node spans memory after move_pfn_range_to_zone(), + * e.g., after the memory block was onlined. + */ + if (pgdat->node_spanned_pages) + return; + + /* + * Especially offline memory blocks might not be spanned by the + * node. They will get spanned by the node once they get onlined. + * However, they link to the node in sysfs and can get onlined later. + */ + rc = for_each_memory_block(&nid, check_no_memblock_for_node_cb); + if (rc) return; - } if (check_and_unmap_cpu_on_node(pgdat)) return;