The patch titled
Subject: mm/memory_hotplug: enforce section granularity when onlining/offlining
has been added to the -mm tree. Its filename is
mm-memory_hotplug-enforce-section-granularity-when-onlining-offlining.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-enforce-section-granularity-when-onlining-offlining.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-memory_hotplug-enforce-section-granularity-when-onlining-offlining.patch
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/memory_hotplug: enforce section granularity when onlining/offlining
Already two people (including me) tried to offline subsections, because
the function looks like it can deal with it. But we really can only
online/offline full sections that are properly aligned (e.g., we can only
mark full sections online/offline via SECTION_IS_ONLINE).
Add a simple safety net to document the restriction now. Current users
(core and powernv/memtrace) respect these restrictions.
Link: https://lkml.kernel.org/r/20200819175957.28465-3-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Charan Teja Reddy <charante@xxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/mm/memory_hotplug.c~mm-memory_hotplug-enforce-section-granularity-when-onlining-offlining
+++ a/mm/memory_hotplug.c
@@ -801,6 +801,11 @@ int __ref online_pages(unsigned long pfn
int ret;
struct memory_notify arg;
+ /* We can only online full sections (e.g., SECTION_IS_ONLINE) */
+ if (WARN_ON_ONCE(!nr_pages ||
+ !IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION)))
+ return -EINVAL;
+
mem_hotplug_begin();
/* associate pfn range with the zone */
@@ -1485,6 +1490,11 @@ int __ref offline_pages(unsigned long st
struct memory_notify arg;
char *reason;
+ /* We can only offline full sections (e.g., SECTION_IS_ONLINE) */
+ if (WARN_ON_ONCE(!nr_pages ||
+ !IS_ALIGNED(start_pfn | nr_pages, PAGES_PER_SECTION)))
+ return -EINVAL;
+
mem_hotplug_begin();
/*
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-page_alloc-tweak-comments-in-has_unmovable_pages.patch
mm-page_isolation-exit-early-when-pageblock-is-isolated-in-set_migratetype_isolate.patch
mm-page_isolation-drop-warn_on_once-in-set_migratetype_isolate.patch
mm-page_isolation-cleanup-set_migratetype_isolate.patch
virtio-mem-dont-special-case-zone_movable.patch
mm-document-semantics-of-zone_movable.patch
mm-memory_hotplug-inline-__offline_pages-into-offline_pages.patch
mm-memory_hotplug-enforce-section-granularity-when-onlining-offlining.patch
mm-memory_hotplug-simplify-page-offlining.patch
mm-page_alloc-simplify-__offline_isolated_pages.patch
mm-memory_hotplug-drop-nr_isolate_pageblock-in-offline_pages.patch
mm-page_isolation-simplify-return-value-of-start_isolate_page_range.patch
mm-memory_hotplug-simplify-page-onlining.patch
mm-page_alloc-drop-stale-pageblock-comment-in-memmap_init_zone.patch
mm-pass-migratetype-into-memmap_init_zone-and-move_pfn_range_to_zone.patch
mm-memory_hotplug-mark-pageblocks-migrate_isolate-while-onlining-memory.patch
