On 6/25/21 5:02 AM, Michael S. Tsirkin wrote:

On Thu, Jun 24, 2021 at 06:55:13AM -0700, Alexander Duyck wrote:

quoted

On Tue, Jun 22, 2021 at 5:34 PM Gavin Shan [off-list ref] wrote:

quoted

The macro PAGE_REPORTING_MIN_ORDER is defined as the page reporting
threshold. It can't be adjusted at runtime.

This introduces a variable (@page_reporting_order) to replace the
marcro (PAGE_REPORTING_MIN_ORDER). It's also exported so that the
page reporting order can be adjusted at runtime.

Suggested-by: David Hildenbrand <redacted>
Signed-off-by: Gavin Shan <redacted>
---
  Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
  mm/page_reporting.c                             | 8 ++++++--
  mm/page_reporting.h                             | 5 ++---
  3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index cb89dbdedc46..566c4b9af3cd 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt

@@ -3566,6 +3566,12 @@
                         off: turn off poisoning (default)
                         on: turn on poisoning

+       page_reporting.page_reporting_order=
+                       [KNL] Minimal page reporting order
+                       Format: <integer>
+                       Adjust the minimal page reporting order. The page
+                       reporting is disabled when it exceeds (MAX_ORDER-1).
+

Based on the issue found by Stephen I think we may need to tweak this
a bit. I think we may want to just default this value to MAX_ORDER. We
can override this value at registration time with the value provided
either by the reporting device or pageblock_order if prdev->order is
not set.

quoted

diff --git a/mm/page_reporting.c b/mm/page_reporting.c
index df9c5054e1b4..293a8713ef7c 100644
--- a/mm/page_reporting.c
+++ b/mm/page_reporting.c

@@ -10,6 +10,10 @@
  #include "page_reporting.h"
  #include "internal.h"

+unsigned int page_reporting_order = pageblock_order;

Rather than setting this to pageblock_order directly you can set this
to MAX_ORDER which should be constant. Then we can just add some
checks in page_reporting_register to update it when pageblock_order is
less than page_reporting_order.

Then in the next patch you could tweak it so that it will use
"prdev->order ? : pageblock_order" instead of just pageblock_order.

I like that! Much cleaner ... the patch is in -mm now, I think it's a
good idea to drop it and update to use this idea.

Thanks, Alex and Michael. v4 was posted to include the changes. Besides,
"module.h" is missed in page_reporting.c as Andrew found. All the changes
are squeezed to PATCH[2] and PATCH[3].

Andrew, could you help to replace the patches with v4 in linux-mm tree?
Sorry for work to you :)

Thanks,
Gavin