[merged] mm-memory_hotplug-enforce-section-granularity-when-onlining-offlining.patch removed from -mm tree

[merged] mm-memory_hotplug-enforce-section-granularity-when-onlining-offlining.patch removed from -mm tree

[akpm]

The patch titled
     Subject: mm/memory_hotplug: enforce section granularity when onlining/offlining
has been removed from the -mm tree.  Its filename was
     mm-memory_hotplug-enforce-section-granularity-when-onlining-offlining.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: David Hildenbrand <david@redhat.com>
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@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Charan Teja Reddy <charante@codeaurora.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michel Lespinasse <walken@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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
@@ -809,6 +809,11 @@ 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 */
@@ -1494,6 +1499,11 @@ 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@redhat.com are