[merged] mm-page_alloc-tweak-comments-in-has_unmovable_pages.patch removed from -mm tree

[merged] mm-page_alloc-tweak-comments-in-has_unmovable_pages.patch removed from -mm tree

[akpm]

The patch titled
     Subject: mm/page_alloc: tweak comments in has_unmovable_pages()
has been removed from the -mm tree.  Its filename was
     mm-page_alloc-tweak-comments-in-has_unmovable_pages.patch

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

------------------------------------------------------
From: David Hildenbrand <david@redhat.com>
Subject: mm/page_alloc: tweak comments in has_unmovable_pages()

Patch series "mm / virtio-mem: support ZONE_MOVABLE", v5.

When introducing virtio-mem, the semantics of ZONE_MOVABLE were rather
unclear, which is why we special-cased ZONE_MOVABLE such that partially
plugged blocks would never end up in ZONE_MOVABLE.

Now that the semantics are much clearer (and are documented in patch #6),
let's support partially plugged memory blocks in ZONE_MOVABLE, allowing
partially plugged memory blocks to be online to ZONE_MOVABLE and also
unplugging from such memory blocks.  This avoids surprises when onlining
of memory blocks suddenly fails, just because they are not completely
populated by virtio-mem (yet).

This is especially helpful for testing, but also paves the way for
virtio-mem optimizations, allowing more memory to get reliably unplugged.

Cleanup has_unmovable_pages() and set_migratetype_isolate(), providing
better documentation of how ZONE_MOVABLE interacts with different kind of
unmovable pages (memory offlining vs.  alloc_contig_range()).


This patch (of 6):

Let's move the split comment regarding bootmem allocations and memory
holes, especially in the context of ZONE_MOVABLE, to the PageReserved()
check.

Link: http://lkml.kernel.org/r/20200816125333.7434-1-david@redhat.com
Link: http://lkml.kernel.org/r/20200816125333.7434-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |   22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

--- a/mm/page_alloc.c~mm-page_alloc-tweak-comments-in-has_unmovable_pages
+++ a/mm/page_alloc.c
@@ -8235,14 +8235,6 @@ struct page *has_unmovable_pages(struct
 	unsigned long iter = 0;
 	unsigned long pfn = page_to_pfn(page);
 
-	/*
-	 * TODO we could make this much more efficient by not checking every
-	 * page in the range if we know all of them are in MOVABLE_ZONE and
-	 * that the movable zone guarantees that pages are migratable but
-	 * the later is not the case right now unfortunatelly. E.g. movablecore
-	 * can still lead to having bootmem allocations in zone_movable.
-	 */
-
 	if (is_migrate_cma_page(page)) {
 		/*
 		 * CMA allocations (alloc_contig_range) really need to mark
@@ -8261,6 +8253,12 @@ struct page *has_unmovable_pages(struct
 
 		page = pfn_to_page(pfn + iter);
 
+		/*
+		 * Both, bootmem allocations and memory holes are marked
+		 * PG_reserved and are unmovable. We can even have unmovable
+		 * allocations inside ZONE_MOVABLE, for example when
+		 * specifying "movablecore".
+		 */
 		if (PageReserved(page))
 			return page;
 
@@ -8334,14 +8332,6 @@ struct page *has_unmovable_pages(struct
 		 * it.  But now, memory offline itself doesn't call
 		 * shrink_node_slabs() and it still to be fixed.
 		 */
-		/*
-		 * If the page is not RAM, page_count()should be 0.
-		 * we don't need more check. This is an _used_ not-movable page.
-		 *
-		 * The problematic thing here is PG_reserved pages. PG_reserved
-		 * is set to both of a memory hole page and a _used_ kernel
-		 * page at boot.
-		 */
 		return page;
 	}
 	return NULL;
_

Patches currently in -mm which might be from david@redhat.com are

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
kernel-resource-make-release_mem_region_adjustable-never-fail.patch
kernel-resource-move-and-rename-ioresource_mem_driver_managed.patch
mm-memory_hotplug-guard-more-declarations-by-config_memory_hotplug.patch
mm-memory_hotplug-prepare-passing-flags-to-add_memory-and-friends.patch
mm-memory_hotplug-memhp_merge_resource-to-specify-merging-of-system-ram-resources.patch
virtio-mem-try-to-merge-system-ram-resources.patch
xen-balloon-try-to-merge-system-ram-resources.patch
hv_balloon-try-to-merge-system-ram-resources.patch
kernel-resource-make-iomem_resource-implicit-in-release_mem_region_adjustable.patch
mm-page_alloc-convert-report-flag-of-__free_one_page-to-a-proper-flag.patch
mm-page_alloc-place-pages-to-tail-in-__putback_isolated_page.patch
mm-page_alloc-move-pages-to-tail-in-move_to_free_list.patch
mm-page_alloc-place-pages-to-tail-in-__free_pages_core.patch
mm-memory_hotplug-update-comment-regarding-zone-shuffling.patch