On 01.07.25 08:13, Harry Yoo wrote:
On Mon, Jun 30, 2025 at 12:14:01PM -0400, Zi Yan wrote:
On 30 Jun 2025, at 12:01, Lorenzo Stoakes wrote:
On Mon, Jun 30, 2025 at 02:59:46PM +0200, David Hildenbrand wrote:
Let the page freeing code handle clearing the page type.
Why is this advantageous? We want to keep the page marked offline for longer?
Acked-by: Zi Yan <ziy@xxxxxxxxxx>
Acked-by: Harry Yoo <harry.yoo@xxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
On assumption this UINT_MAX stuff is sane :)) I mean this is straightforward I
guess:
This is how page type is cleared.
See: https://elixir.bootlin.com/linux/v6.15.4/source/include/linux/page-flags.h#L1013.
I agree with you that patch 4 should have a comment in free_pages_prepare()
about what the code is for and why UINT_MAX is used.
Or instead of comment, maybe something like this:
/* Clear any page type */
static __always_inline void __ClearPageType(struct page *page)
{
VM_WARN_ON_ONCE_PAGE(!page_has_type(page), page);
page->page_type = UINT_MAX;
}
in patch 4:
if (unlikely(page_has_type(page)))
__ClearPageType(page);
I don't think we should do that. It's very specialized code that nobody
should be reusing.
And it will all change once Willy reworks the page_type vs. _mapcount
overlay.
--
Cheers,
David / dhildenb
