Re: [PATCH RFC 04/29] mm/page_alloc: allow for making page types sticky until freed
From: Zi Yan <ziy@nvidia.com>
Date: 2025-06-18 18:43:36
Also in:
linux-doc, linux-fsdevel, linux-mm, lkml, virtualization
On 18 Jun 2025, at 13:39, David Hildenbrand wrote:
quoted hunk ↗ jump to hunk
Let's allow for not clearing a page type before freeing a page to the buddy. We'll focus on having a type set on the first page of a larger allocation only. With this change, we can reliably identify typed folios even though they might be in the process of getting freed, which will come in handy in migration code (at least in the transition phase). Signed-off-by: David Hildenbrand <redacted> --- mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 858bc17653af9..44e56d31cfeb1 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c@@ -1380,6 +1380,9 @@ __always_inline bool free_pages_prepare(struct page *page, mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); page->mapping = NULL; } + if (unlikely(page_has_type(page))) + page->page_type = UINT_MAX; + if (is_check_pages_enabled()) { if (free_page_is_bad(page)) bad++;
Should we be pedantic to only do this for PageOffline and PageZsmalloc
and warn for the rest page types?
Something like:
if (unlikely(page_has_type(page))) {
if (PageOffline(page) || PageZsmalloc(page))
page->page_type = UINT_MAX;
else
VM_WARN_ONCE_PAGE(1, page);
}
Best Regards,
Yan, Zi