path: root/mm/memory_hotplug.c
diff options
authorDavid Hildenbrand <david@redhat.com>2019-11-30 17:54:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-01 12:59:04 -0800
commit0ee5f4f31d365ff9867a8002a8b37f9aa61b21d2 (patch)
treef103b41c0c65cf1f904dd18718bbea6e179e7eba /mm/memory_hotplug.c
parentmm/memory_hotplug: remove __online_page_free() and __online_page_increment_counters() (diff)
mm/page_alloc.c: don't set pages PageReserved() when offlining
Patch series "mm: Memory offlining + page isolation cleanups", v2. This patch (of 2): We call __offline_isolated_pages() from __offline_pages() after all pages were isolated and are either free (PageBuddy()) or PageHWPoison. Nothing can stop us from offlining memory at this point. In __offline_isolated_pages() we first set all affected memory sections offline (offline_mem_sections(pfn, end_pfn)), to mark the memmap as invalid (pfn_to_online_page() will no longer succeed), and then walk over all pages to pull the free pages from the free lists (to the isolated free lists, to be precise). Note that re-onlining a memory block will result in the whole memmap getting reinitialized, overwriting any old state. We already poision the memmap when offlining is complete to find any access to stale/uninitialized memmaps. So, setting the pages PageReserved() is not helpful. The memap is marked offline and all pageblocks are isolated. As soon as offline, the memmap is stale either way. This looks like a leftover from ancient times where we initialized the memmap when adding memory and not when onlining it (the pages were set PageReserved so re-onling would work as expected). Link: http://lkml.kernel.org/r/20191021172353.3056-2-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Oscar Salvador <osalvador@suse.de> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
1 files changed, 1 insertions, 3 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 5e9d18849a0c..929d4209e78b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1384,9 +1384,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
return ret;
- * remove from free_area[] and mark all as Reserved.
- */
+/* Mark all sections offline and remove all free pages from the buddy. */
static int
offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
void *data)