Commit 91f386bf authored by Mike Kravetz's avatar Mike Kravetz Committed by Andrew Morton
Browse files

hugetlb: batch freeing of vmemmap pages 

Now that batching of hugetlb vmemmap optimization processing is possible,
batch the freeing of vmemmap pages.  When freeing vmemmap pages for a
hugetlb page, we add them to a list that is freed after the entire batch
has been processed.

This enhances the ability to return contiguous ranges of memory to the low
level allocators.

Link: https://lkml.kernel.org/r/20231019023113.345257-6-mike.kravetz@oracle.com


Signed-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: default avatarMuchun Song <songmuchun@bytedance.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Konrad Dybcio <konradybcio@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Usama Arif <usama.arif@bytedance.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent cfb8c750

mm/hugetlb_vmemmap.c

+56 −26
Original line number Diff line number Diff line
@@ -251,7 +251,7 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, 
	}



	entry = mk_pte(walk->reuse_page, pgprot);

	list_add_tail(&page->lru, walk->vmemmap_pages);

	list_add(&page->lru, walk->vmemmap_pages);

	set_pte_at(&init_mm, addr, pte, entry);

}
@@ -306,18 +306,20 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, 
 * @end:	end address of the vmemmap virtual address range that we want to

 *		remap.

 * @reuse:	reuse address.

 * @vmemmap_pages: list to deposit vmemmap pages to be freed.  It is callers

 *		responsibility to free pages.

 *

 * Return: %0 on success, negative error code otherwise.

 */

static int vmemmap_remap_free(unsigned long start, unsigned long end,

			      unsigned long reuse)

			      unsigned long reuse,

			      struct list_head *vmemmap_pages)

{

	int ret;

	LIST_HEAD(vmemmap_pages);

	struct vmemmap_remap_walk walk = {

		.remap_pte	= vmemmap_remap_pte,

		.reuse_addr	= reuse,

		.vmemmap_pages	= &vmemmap_pages,

		.vmemmap_pages	= vmemmap_pages,

	};

	int nid = page_to_nid((struct page *)reuse);

	gfp_t gfp_mask = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
@@ -334,7 +336,7 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, 
	if (walk.reuse_page) {

		copy_page(page_to_virt(walk.reuse_page),

			  (void *)walk.reuse_addr);

		list_add(&walk.reuse_page->lru, &vmemmap_pages);

		list_add(&walk.reuse_page->lru, vmemmap_pages);

	}



	/*
@@ -365,15 +367,13 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, 
		walk = (struct vmemmap_remap_walk) {

			.remap_pte	= vmemmap_restore_pte,

			.reuse_addr	= reuse,

			.vmemmap_pages	= &vmemmap_pages,

			.vmemmap_pages	= vmemmap_pages,

		};



		vmemmap_remap_range(reuse, end, &walk);

	}

	mmap_read_unlock(&init_mm);



	free_vmemmap_page_list(&vmemmap_pages);



	return ret;

}
@@ -389,7 +389,7 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end, 
		page = alloc_pages_node(nid, gfp_mask, 0);

		if (!page)

			goto out;

		list_add_tail(&page->lru, list);

		list_add(&page->lru, list);

	}



	return 0;
@@ -577,24 +577,17 @@ static bool vmemmap_should_optimize(const struct hstate *h, const struct page *h 
	return true;

}



/**

 * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages.

 * @h:		struct hstate.

 * @head:	the head page whose vmemmap pages will be optimized.

 *

 * This function only tries to optimize @head's vmemmap pages and does not

 * guarantee that the optimization will succeed after it returns. The caller

 * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages

 * have been optimized.

 */

void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)

static int __hugetlb_vmemmap_optimize(const struct hstate *h,

					struct page *head,

					struct list_head *vmemmap_pages)

{

	int ret = 0;

	unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;

	unsigned long vmemmap_reuse;



	VM_WARN_ON_ONCE(!PageHuge(head));

	if (!vmemmap_should_optimize(h, head))

		return;

		return ret;



	static_branch_inc(&hugetlb_optimize_vmemmap_key);
@@ -604,21 +597,58 @@ void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head) 


	/*

	 * Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end)

	 * to the page which @vmemmap_reuse is mapped to, then free the pages

	 * which the range [@vmemmap_start, @vmemmap_end] is mapped to.

	 * to the page which @vmemmap_reuse is mapped to.  Add pages previously

	 * mapping the range to vmemmap_pages list so that they can be freed by

	 * the caller.

	 */

	if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse))

	ret = vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse, vmemmap_pages);

	if (ret)

		static_branch_dec(&hugetlb_optimize_vmemmap_key);

	else

		SetHPageVmemmapOptimized(head);



	return ret;

}



/**

 * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages.

 * @h:		struct hstate.

 * @head:	the head page whose vmemmap pages will be optimized.

 *

 * This function only tries to optimize @head's vmemmap pages and does not

 * guarantee that the optimization will succeed after it returns. The caller

 * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages

 * have been optimized.

 */

void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)

{

	LIST_HEAD(vmemmap_pages);



	__hugetlb_vmemmap_optimize(h, head, &vmemmap_pages);

	free_vmemmap_page_list(&vmemmap_pages);

}



void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list)

{

	struct folio *folio;

	LIST_HEAD(vmemmap_pages);



	list_for_each_entry(folio, folio_list, lru)

		hugetlb_vmemmap_optimize(h, &folio->page);

	list_for_each_entry(folio, folio_list, lru) {

		int ret = __hugetlb_vmemmap_optimize(h, &folio->page,

								&vmemmap_pages);



		/*

		 * Pages to be freed may have been accumulated.  If we

		 * encounter an ENOMEM,  free what we have and try again.

		 */

		if (ret == -ENOMEM && !list_empty(&vmemmap_pages)) {

			free_vmemmap_page_list(&vmemmap_pages);

			INIT_LIST_HEAD(&vmemmap_pages);

			__hugetlb_vmemmap_optimize(h, &folio->page, &vmemmap_pages);

		}

	}



	free_vmemmap_page_list(&vmemmap_pages);

}



static struct ctl_table hugetlb_vmemmap_sysctls[] = {