Messages in this thread Patch in this message | | | From | Zi Yan <> | Subject | [PATCH v1 02/12] mm: check page validity when find a buddy page in a non-contiguous zone | Date | Wed, 21 Sep 2022 21:12:42 -0400 |
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From: Zi Yan <ziy@nvidia.com>
When MAX_ORDER > section size, buddy page might not be valid when the zone is non-contiguous. Check it and return NULL if buddy page is not valid.
For PFNs that not aligned to MAX_ORDER (usually at the beginning and end of a zone), __free_pages_memory() clamps down the order to make sure invalid PFN will not show up as a buddy PFN.
Signed-off-by: Zi Yan <ziy@nvidia.com> --- mm/internal.h | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/mm/internal.h b/mm/internal.h index b3002e03c28f..22fb1e6e3541 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -330,12 +330,16 @@ static inline struct page *find_buddy_page_pfn(struct page *page, unsigned long pfn, unsigned int order, unsigned long *buddy_pfn) { unsigned long __buddy_pfn = __find_buddy_pfn(pfn, order); + struct zone *zone = page_zone(page); struct page *buddy; buddy = page + (__buddy_pfn - pfn); if (buddy_pfn) *buddy_pfn = __buddy_pfn; + if (unlikely(!zone->contiguous && !pfn_valid(__buddy_pfn))) + return NULL; + if (page_is_buddy(page, buddy, order)) return buddy; return NULL; -- 2.35.1
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