Re: [PATCH v3 2/4] mm/page_reporting: Export reporting order as module parameter

[Gavin Shan <gshan@redhat.com>]

On 6/25/21 5:02 AM, Michael S. Tsirkin wrote:
> On Thu, Jun 24, 2021 at 06:55:13AM -0700, Alexander Duyck wrote:
>> On Tue, Jun 22, 2021 at 5:34 PM Gavin Shan <gshan@redhat.com> wrote:
>>>
>>> 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 <david@redhat.com>
>>> Signed-off-by: Gavin Shan <gshan@redhat.com>
>>> ---
>>>   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.
>>
>>> 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