On 6/26/21 12:18 AM, Alexander Duyck wrote:

On Thu, Jun 24, 2021 at 7:20 PM Gavin Shan [off-list ref] wrote:

quoted

The page reporting threshold is currently equal to @pageblock_order, which
is 13 and 512MB on arm64 with 64KB base page size selected. The page
reporting won't be triggered if the freeing page can't come up with a free
area like that huge. The condition is hard to be met, especially when the
system memory becomes fragmented.

This series intends to solve the issue by having page reporting threshold
as 5 (2MB) on arm64 with 64KB base page size. The patches are organized as:

    PATCH[1/4] Fix some coding style in __page_reporting_request().
    PATCH[2/4] Represents page reporting order with variable so that it can
               be exported as module parameter.
    PATCH[3/4] Allows the device driver (e.g. virtio_balloon) to specify
               the page reporting order when the device info is registered.
    PATCH[4/4] Specifies the page reporting order to 5, corresponding to
               2MB in size on ARM64 when 64KB base page size is used.

Changelog
=========
v5:
    * Restore @page_reporting_order to @pageblock_order when
      device is registered in PATCH[2/4] to keep "git bisect"
      friendly at least.                                           (Alex)

These latest changes address the concerns I had.

Thanks again for your review, Alex. However, v4 was merged and it's fine
since v5 only resolves 'git-bisect' friendly issue on PATCH[v4 2/4].

Thanks,
Gavin