From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:50122 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730937AbhATIeQ (ORCPT ); Wed, 20 Jan 2021 03:34:16 -0500 From: Anshuman Khandual Subject: Re: [PATCH V3 1/3] mm/memory_hotplug: Prevalidate the address range being added with platform References: <1610975582-12646-1-git-send-email-anshuman.khandual@arm.com> <1610975582-12646-2-git-send-email-anshuman.khandual@arm.com> <691872bb-b251-83e0-126e-afd54683c83e@redhat.com> Message-ID: <3d4f3b14-0715-b2b3-b015-04b8a77abfb8@arm.com> Date: Wed, 20 Jan 2021 14:03:45 +0530 MIME-Version: 1.0 In-Reply-To: <691872bb-b251-83e0-126e-afd54683c83e@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit List-ID: To: David Hildenbrand , linux-mm@kvack.org, akpm@linux-foundation.org, hca@linux.ibm.com, catalin.marinas@arm.com Cc: Oscar Salvador , Vasily Gorbik , Will Deacon , Ard Biesheuvel , Mark Rutland , linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org On 1/19/21 5:51 PM, David Hildenbrand wrote: > On 18.01.21 14:12, Anshuman Khandual wrote: >> This introduces memhp_range_allowed() which can be called in various memory >> hotplug paths to prevalidate the address range which is being added, with >> the platform. Then memhp_range_allowed() calls memhp_get_pluggable_range() >> which provides applicable address range depending on whether linear mapping >> is required or not. For ranges that require linear mapping, it calls a new >> arch callback arch_get_mappable_range() which the platform can override. So >> the new callback, in turn provides the platform an opportunity to configure >> acceptable memory hotplug address ranges in case there are constraints. >> >> This mechanism will help prevent platform specific errors deep down during >> hotplug calls. This drops now redundant check_hotplug_memory_addressable() >> check in __add_pages() but instead adds a VM_BUG_ON() check which would > > In this patch, you keep the __add_pages() checks. But as discussed, we > could perform it in mm/memremap.c:pagemap_range() insted and convert it > to a VM_BUG_ON(). Just to be sure, will the following change achieve what you are suggesting here. pagemap_range() after this change, will again be the same like the V1 series. --- mm/memory_hotplug.c | 3 +-- mm/memremap.c | 12 +++++------- 2 files changed, 6 insertions(+), 9 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 46faa914aa25..10d4ec8f349c 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -304,8 +304,7 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages, if (WARN_ON_ONCE(!params->pgprot.pgprot)) return -EINVAL; - if(!memhp_range_allowed(PFN_PHYS(pfn), nr_pages * PAGE_SIZE, false)) - return -E2BIG; + VM_BUG_ON(!memhp_range_allowed(PFN_PHYS(pfn), nr_pages * PAGE_SIZE, false)); if (altmap) { /* diff --git a/mm/memremap.c b/mm/memremap.c index e15b13736f6a..26c1825756cc 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -185,6 +185,7 @@ static void dev_pagemap_percpu_release(struct percpu_ref *ref) static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, int range_id, int nid) { + const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE; struct range *range = &pgmap->ranges[range_id]; struct dev_pagemap *conflict_pgmap; int error, is_ram; @@ -230,6 +231,9 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, if (error) goto err_pfn_remap; + if (!memhp_range_allowed(range->start, range_len(range), !is_private)) + goto err_pfn_remap; + mem_hotplug_begin(); /* @@ -243,7 +247,7 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, * the CPU, we do want the linear mapping and thus use * arch_add_memory(). */ - if (pgmap->type == MEMORY_DEVICE_PRIVATE) { + if (is_private) { error = add_pages(nid, PHYS_PFN(range->start), PHYS_PFN(range_len(range)), params); } else { @@ -253,12 +257,6 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, goto err_kasan; } - if (!memhp_range_allowed(range->start, range_len(range), true)) { - error = -ERANGE; - mem_hotplug_done(); - goto err_add_memory; - } - error = arch_add_memory(nid, range->start, range_len(range), params); } -- 2.20.1