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From: Michal Hocko <mhocko@suse.com>
To: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/5] mm,memory_hotplug: Allocate memmap from the added memory range
Date: Thu, 25 Mar 2021 17:47:30 +0100	[thread overview]
Message-ID: <YFy+olsdS4iwrovN@dhcp22.suse.cz> (raw)
In-Reply-To: <YFy8ARml4R7/snVs@dhcp22.suse.cz>

On Thu 25-03-21 17:36:22, Michal Hocko wrote:
> If all it takes is to make pfn_to_online_page work (and my
> previous attempt is incorrect because it should consult block rather
> than section pfn range)

This should work.

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 9697acfe96eb..e50d685be8ab 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -510,6 +510,23 @@ static struct memory_block *find_memory_block_by_id(unsigned long block_id)
 	return mem;
 }
 
+struct page *is_vmemmap_page(unsigned long pfn)
+{
+	unsigned long nr = pfn_to_section_nr(pfn);
+	struct memory_block *mem;
+	unsigned long block_pfn;
+
+	mem = find_memory_block_by_id(memory_block_id(nr));
+	if (!mem || !mem->nr_vmemmap_pages)
+		return NULL;
+
+	block_pfn = section_nr_to_pfn(mem->start_section_nr);
+	if (pfn - block_pfn > mem->nr_vmemmap_pages)
+		return NULL;
+
+	return pfn_to_page(pfn);
+}
+
 /*
  * Called under device_hotplug_lock.
  */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 754026a9164d..760bf3ad48d5 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -304,8 +304,16 @@ struct page *pfn_to_online_page(unsigned long pfn)
 		return NULL;
 
 	ms = __nr_to_section(nr);
-	if (!online_section(ms))
+	if (!online_section(ms)) {
+		/*
+		 * vmemmap reserved space can eat up a whole section which then
+		 * never gets onlined because it doesn't contain any memory to
+		 * online.
+		 */
+		if (memmap_on_memory)
+			return is_vmemmap_page(pfn);
 		return NULL;
+	}
 
 	/*
 	 * Save some code text when online_section() +
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2021-03-25 16:48 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-19  9:26 [PATCH v5 0/5] Allocate memmap from hotadded memory (per device) Oscar Salvador
2021-03-19  9:26 ` [PATCH v5 1/5] mm,memory_hotplug: Allocate memmap from the added memory range Oscar Salvador
2021-03-19 10:20   ` David Hildenbrand
2021-03-19 10:31     ` Oscar Salvador
2021-03-19 12:04       ` David Hildenbrand
2021-03-23 10:11   ` Michal Hocko
2021-03-24 10:12     ` Oscar Salvador
2021-03-24 12:03       ` Michal Hocko
2021-03-24 12:10         ` Michal Hocko
2021-03-24 12:23           ` David Hildenbrand
2021-03-24 12:37             ` Michal Hocko
2021-03-24 13:13               ` David Hildenbrand
2021-03-24 13:40                 ` Michal Hocko
2021-03-24 14:05                   ` David Hildenbrand
2021-03-24 13:27         ` Oscar Salvador
2021-03-24 14:42         ` Michal Hocko
2021-03-24 14:52           ` David Hildenbrand
2021-03-24 16:04             ` Michal Hocko
2021-03-24 19:16               ` David Hildenbrand
2021-03-25  8:07                 ` Oscar Salvador
2021-03-25  9:17                   ` Michal Hocko
2021-03-25 10:55                     ` Oscar Salvador
2021-03-25 11:08                       ` David Hildenbrand
2021-03-25 11:23                         ` Oscar Salvador
2021-03-25 12:35                         ` Michal Hocko
2021-03-25 12:40                           ` David Hildenbrand
2021-03-25 14:08                             ` Michal Hocko
2021-03-25 14:09                               ` David Hildenbrand
2021-03-25 14:34                                 ` Michal Hocko
2021-03-25 14:46                                   ` David Hildenbrand
2021-03-25 15:12                                     ` Michal Hocko
2021-03-25 15:19                                       ` David Hildenbrand
2021-03-25 15:35                                         ` Michal Hocko
2021-03-25 15:40                                           ` David Hildenbrand
2021-03-25 16:07                                           ` Michal Hocko
2021-03-25 16:20                                             ` David Hildenbrand
2021-03-25 16:36                                               ` Michal Hocko
2021-03-25 16:47                                                 ` Michal Hocko [this message]
2021-03-25 16:55                                                   ` David Hildenbrand
2021-03-25 22:06                                                   ` Oscar Salvador
2021-03-26  8:35                                                     ` Michal Hocko
2021-03-26  8:52                                                       ` David Hildenbrand
2021-03-26  8:57                                                         ` Oscar Salvador
2021-03-26 12:15                                                           ` Oscar Salvador
2021-03-26 13:36                                                             ` David Hildenbrand
2021-03-26 14:38                                                         ` Michal Hocko
2021-03-26 14:53                                                           ` David Hildenbrand
2021-03-26 15:31                                                             ` Michal Hocko
2021-03-26 16:03                                                               ` David Hildenbrand
2021-03-26  8:55                                                       ` Oscar Salvador
2021-03-26  9:11                                                         ` Michal Hocko
2021-03-25 18:08                                                 ` David Hildenbrand
2021-03-25 12:26                       ` Michal Hocko
2021-03-25 14:02                         ` Oscar Salvador
2021-03-25 14:40                           ` Michal Hocko
2021-03-19  9:26 ` [PATCH v5 2/5] acpi,memhotplug: Enable MHP_MEMMAP_ON_MEMORY when supported Oscar Salvador
2021-03-23 10:40   ` Michal Hocko
2021-03-19  9:26 ` [PATCH v5 3/5] mm,memory_hotplug: Add kernel boot option to enable memmap_on_memory Oscar Salvador
2021-03-23 10:47   ` Michal Hocko
2021-03-24  8:45     ` Oscar Salvador
2021-03-24  9:02       ` Michal Hocko
2021-03-19  9:26 ` [PATCH v5 4/5] x86/Kconfig: Introduce ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE Oscar Salvador
2021-03-19  9:26 ` [PATCH v5 5/5] arm64/Kconfig: " Oscar Salvador

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