The patch titled
Subject: mm/page_reporting: allow driver to specify reporting order
has been added to the -mm tree. Its filename is
mm-page_reporting-allow-driver-to-specify-reporting-order.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-page_reporting-allow-driver-to-specify-reporting-order.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-page_reporting-allow-driver-to-specify-reporting-order.patch
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------------------------------------------------------
From: Gavin Shan <gshan@xxxxxxxxxx>
Subject: mm/page_reporting: allow driver to specify reporting order
The page reporting order (threshold) is sticky to @pageblock_order by
default. The page reporting can never be triggered because the freeing
page can't come up with a free area like that huge. The situation becomes
worse when the system memory becomes heavily fragmented.
For example, the following configurations are used on ARM64 when 64KB base
page size is enabled. In this specific case, the page reporting won't be
triggered until the freeing page comes up with a 512MB free area. That's
hard to be met, especially when the system memory becomes heavily
fragmented.
PAGE_SIZE: 64KB
HPAGE_SIZE: 512MB
pageblock_order: 13 (512MB)
MAX_ORDER: 14
This allows the drivers to specify the page reporting order when the page
reporting device is registered. It falls back to @pageblock_order if it's
not specified by the driver. The existing users (hv_balloon and
virtio_balloon) don't specify it and @pageblock_order is still taken as
their page reporting order. So this shouldn't introduce any functional
changes.
Link: https://lkml.kernel.org/r/20210625014710.42954-4-gshan@xxxxxxxxxx
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
Reviewed-by: Alexander Duyck <alexanderduyck@xxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page_reporting.h | 3 +++
mm/page_reporting.c | 6 ++++++
2 files changed, 9 insertions(+)
--- a/include/linux/page_reporting.h~mm-page_reporting-allow-driver-to-specify-reporting-order
+++ a/include/linux/page_reporting.h
@@ -18,6 +18,9 @@ struct page_reporting_dev_info {
/* Current state of page reporting */
atomic_t state;
+
+ /* Minimal order of page reporting */
+ unsigned int order;
};
/* Tear-down and bring-up for page reporting devices */
--- a/mm/page_reporting.c~mm-page_reporting-allow-driver-to-specify-reporting-order
+++ a/mm/page_reporting.c
@@ -329,6 +329,12 @@ int page_reporting_register(struct page_
goto err_out;
}
+ /*
+ * Update the page reporting order if it's specified by driver.
+ * Otherwise, it falls back to @pageblock_order.
+ */
+ page_reporting_order = prdev->order ? : pageblock_order;
+
/* initialize state and work structures */
atomic_set(&prdev->state, PAGE_REPORTING_IDLE);
INIT_DELAYED_WORK(&prdev->work, &page_reporting_process);
_
Patches currently in -mm which might be from gshan@xxxxxxxxxx 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
