Commit a9deb800 authored by Kefeng Wang's avatar Kefeng Wang Committed by Andrew Morton
Browse files

mm: page_alloc: add __split_page() 

Factor out the splitting of non-compound page from make_alloc_exact() and
split_page() into a new helper function __split_page().

While at it, convert the VM_BUG_ON_PAGE() into a VM_WARN_ON_PAGE().

Link: https://lkml.kernel.org/r/20260109093136.1491549-3-wangkefeng.wang@huawei.com


Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarMuchun Song <muchun.song@linux.dev>
Reviewed-by: default avatarZi Yan <ziy@nvidia.com>
Reviewed-by: default avatarSidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 01152bd2

include/linux/mmdebug.h

+10 −0
Original line number Diff line number Diff line
@@ -47,6 +47,15 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); 
			BUG();						\

		}							\

	} while (0)

#define VM_WARN_ON_PAGE(cond, page)		({			\

	int __ret_warn = !!(cond);					\

									\

	if (unlikely(__ret_warn)) {					\

		dump_page(page, "VM_WARN_ON_PAGE(" __stringify(cond)")");\

		WARN_ON(1);						\

	}								\

	unlikely(__ret_warn);						\

})

#define VM_WARN_ON_ONCE_PAGE(cond, page)	({			\

	static bool __section(".data..once") __warned;			\

	int __ret_warn_once = !!(cond);					\
@@ -122,6 +131,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); 
#define VM_BUG_ON_MM(cond, mm) VM_BUG_ON(cond)

#define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)

#define VM_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)

#define VM_WARN_ON_PAGE(cond, page)  BUILD_BUG_ON_INVALID(cond)

#define VM_WARN_ON_ONCE_PAGE(cond, page)  BUILD_BUG_ON_INVALID(cond)

#define VM_WARN_ON_FOLIO(cond, folio)  BUILD_BUG_ON_INVALID(cond)

#define VM_WARN_ON_ONCE_FOLIO(cond, folio)  BUILD_BUG_ON_INVALID(cond)

mm/page_alloc.c

+13 −8
Original line number Diff line number Diff line
@@ -3107,6 +3107,15 @@ void free_unref_folios(struct folio_batch *folios) 
	folio_batch_reinit(folios);

}



static void __split_page(struct page *page, unsigned int order)

{

	VM_WARN_ON_PAGE(PageCompound(page), page);



	split_page_owner(page, order, 0);

	pgalloc_tag_split(page_folio(page), order, 0);

	split_page_memcg(page, order);

}



/*

 * split_page takes a non-compound higher-order page, and splits it into

 * n (1<<order) sub-pages: page[0..n]
@@ -3119,14 +3128,12 @@ void split_page(struct page *page, unsigned int order) 
{

	int i;



	VM_BUG_ON_PAGE(PageCompound(page), page);

	VM_BUG_ON_PAGE(!page_count(page), page);

	VM_WARN_ON_PAGE(!page_count(page), page);



	for (i = 1; i < (1 << order); i++)

		set_page_refcounted(page + i);

	split_page_owner(page, order, 0);

	pgalloc_tag_split(page_folio(page), order, 0);

	split_page_memcg(page, order);



	__split_page(page, order);

}

EXPORT_SYMBOL_GPL(split_page);
@@ -5389,9 +5396,7 @@ static void *make_alloc_exact(unsigned long addr, unsigned int order, 
		struct page *page = virt_to_page((void *)addr);

		struct page *last = page + nr;



		split_page_owner(page, order, 0);

		pgalloc_tag_split(page_folio(page), order, 0);

		split_page_memcg(page, order);

		__split_page(page, order);

		while (page < --last)

			set_page_refcounted(last);