diff mbox series

[126/143] mm,memory_hotplug: relax fully spanned sections check

Message ID 20210505013936.UBlNm_lxU%akpm@linux-foundation.org (mailing list archive)
State New
Headers show
Series [001/143] mm: introduce and use mapping_empty() | expand

Commit Message

Andrew Morton May 5, 2021, 1:39 a.m. UTC
From: Oscar Salvador <osalvador@suse.de>
Subject: mm,memory_hotplug: relax fully spanned sections check

We want {online,offline}_pages to operate on whole memblocks, but
memmap_on_memory will poke pageblock_nr_pages aligned holes in the
beginning, which is a special case we want to allow.  Relax the check to
account for that case.

Link: https://lkml.kernel.org/r/20210421102701.25051-3-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory_hotplug.c |   22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)
diff mbox series

Patch

--- a/mm/memory_hotplug.c~mmmemory_hotplug-relax-fully-spanned-sections-check
+++ a/mm/memory_hotplug.c
@@ -838,9 +838,16 @@  int __ref online_pages(unsigned long pfn
 	int ret;
 	struct memory_notify arg;
 
-	/* We can only online full sections (e.g., SECTION_IS_ONLINE) */
+	/*
+	 * {on,off}lining is constrained to full memory sections (or more
+	 * precisly to memory blocks from the user space POV).
+	 * memmap_on_memory is an exception because it reserves initial part
+	 * of the physical memory space for vmemmaps. That space is pageblock
+	 * aligned.
+	 */
 	if (WARN_ON_ONCE(!nr_pages ||
-			 !IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION)))
+			 !IS_ALIGNED(pfn, pageblock_nr_pages) ||
+			 !IS_ALIGNED(pfn + nr_pages, PAGES_PER_SECTION)))
 		return -EINVAL;
 
 	mem_hotplug_begin();
@@ -1573,9 +1580,16 @@  int __ref offline_pages(unsigned long st
 	int ret, node;
 	char *reason;
 
-	/* We can only offline full sections (e.g., SECTION_IS_ONLINE) */
+	/*
+	 * {on,off}lining is constrained to full memory sections (or more
+	 * precisly to memory blocks from the user space POV).
+	 * memmap_on_memory is an exception because it reserves initial part
+	 * of the physical memory space for vmemmaps. That space is pageblock
+	 * aligned.
+	 */
 	if (WARN_ON_ONCE(!nr_pages ||
-			 !IS_ALIGNED(start_pfn | nr_pages, PAGES_PER_SECTION)))
+			 !IS_ALIGNED(start_pfn, pageblock_nr_pages) ||
+			 !IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION)))
 		return -EINVAL;
 
 	mem_hotplug_begin();