+ virtio_balloon-specify-page-reporting-order-if-needed.patch added to -mm tree

* + virtio_balloon-specify-page-reporting-order-if-needed.patch added to -mm tree
@ 2021-06-23  4:21 akpm
  0 siblings, 0 replies; 2+ messages in thread
From: akpm @ 2021-06-23  4:21 UTC (permalink / raw)
  To: alexanderduyck, anshuman.khandual, catalin.marinas, david, gshan,
	mm-commits, mst, will


The patch titled
     Subject: virtio_balloon: specify page reporting order if needed
has been added to the -mm tree.  Its filename is
     virtio_balloon-specify-page-reporting-order-if-needed.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/virtio_balloon-specify-page-reporting-order-if-needed.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/virtio_balloon-specify-page-reporting-order-if-needed.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Gavin Shan <gshan@redhat.com>
Subject: virtio_balloon: specify page reporting order if needed

The page reporting won't be triggered if the freeing page can't come up
with a free area, whose size is equal or bigger than the threshold (page
reporting order).  The default page reporting order, equal to
@pageblock_order, is too huge on some architectures to trigger page
reporting.  One example is ARM64 when 64KB base page size is used.

      PAGE_SIZE:          64KB
      pageblock_order:    13       (512MB)
      MAX_ORDER:          14

This specifies the page reporting order to 5 (2MB) for this specific case
so that page reporting can be triggered.

Link: https://lkml.kernel.org/r/20210623023418.350616-5-gshan@redhat.com
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/virtio/virtio_balloon.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

--- a/drivers/virtio/virtio_balloon.c~virtio_balloon-specify-page-reporting-order-if-needed
+++ a/drivers/virtio/virtio_balloon.c
@@ -993,6 +993,23 @@ static int virtballoon_probe(struct virt
 			goto out_unregister_oom;
 		}
 
+		/*
+		 * The default page reporting order is @pageblock_order, which
+		 * corresponds to 512MB in size on ARM64 when 64KB base page
+		 * size is used. The page reporting won't be triggered if the
+		 * freeing page can't come up with a free area like that huge.
+		 * So we specify the page reporting order to 5, corresponding
+		 * to 2MB. It helps to avoid THP splitting if 4KB base page
+		 * size is used by host.
+		 *
+		 * Ideally, the page reporting order is selected based on the
+		 * host's base page size. However, it needs more work to report
+		 * that value. The hard-coded order would be fine currently.
+		 */
+#if defined(CONFIG_ARM64) && defined(CONFIG_ARM64_64K_PAGES)
+		vb->pr_dev_info.order = 5;
+#endif
+
 		err = page_reporting_register(&vb->pr_dev_info);
 		if (err)
 			goto out_unregister_oom;
_

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

mm-page_reporting-fix-code-style-in-__page_reporting_request.patch
mm-page_reporting-export-reporting-order-as-module-parameter.patch
mm-page_reporting-allow-driver-to-specify-reporting-order.patch
virtio_balloon-specify-page-reporting-order-if-needed.patch


^ permalink raw reply	[flat|nested] 2+ messages in thread