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mm/memory_hotplug: move debug_pagealloc_map_pages() into online_pages_range()

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In the near future, we want to have a single way to handover PageOffline
pages to the buddy, whereby they could have:

(a) Never been exposed to the buddy before: kept PageOffline when onlining
    the memory block.
(b) Been allocated from the buddy, for example using
    alloc_contig_range() to then be set PageOffline,

Let's start by making generic_online_page()->__free_pages_core() less
special compared to ordinary page freeing (e.g., free_contig_range()),
and perform the debug_pagealloc_map_pages() call unconditionally, even
when the online callback might decide to keep the pages offline.

All pages are already initialized with PageOffline, so nobody touches them
either way.

Link: https://lkml.kernel.org/r/20241203102050.223318-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand
2024-12-03 11:20:50 +01:00
committed by Andrew Morton
parent bef5418d1f
commit dd467f92db
2 changed files with 9 additions and 7 deletions
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10
mm/memory_hotplug.c
View File

@@ -650,6 +650,7 @@ static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
* this and the first chunk to online will be pageblock_nr_pages.
*/
for (pfn = start_pfn; pfn < end_pfn;) {
struct page *page = pfn_to_page(pfn);
int order;
/*
@@ -664,7 +665,14 @@ static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
else
order = MAX_PAGE_ORDER;
(*online_page_callback)(pfn_to_page(pfn), order);
/*
* Exposing the page to the buddy by freeing can cause
* issues with debug_pagealloc enabled: some archs don't
* like double-unmappings. So treat them like any pages that
* were allocated from the buddy.
*/
debug_pagealloc_map_pages(page, 1 << order);
(*online_page_callback)(page, order);
pfn += (1UL << order);
}

6
mm/page_alloc.c
View File

@@ -1295,12 +1295,6 @@ void __meminit __free_pages_core(struct page *page, unsigned int order,
set_page_count(p, 0);
}
/*
* Freeing the page with debug_pagealloc enabled will try to
* unmap it; some archs don't like double-unmappings, so
* map it first.
*/
debug_pagealloc_map_pages(page, nr_pages);
adjust_managed_page_count(page, nr_pages);
} else {
for (loop = 0; loop < nr_pages; loop++, p++) {