On 2023/9/6 05:44, Mike Kravetz wrote:
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.
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
mm/hugetlb_vmemmap.c | 60 ++++++++++++++++++++++++++++----------------
1 file changed, 38 insertions(+), 22 deletions(-)
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 79de984919ef..a715712df831 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -306,18 +306,21 @@ 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);
+ LIST_HEAD(freed_pages);
IIUC, we could reuse the parameter of @vmemmap_pages directly instead of
a temporary variable, could it be dropped?
struct vmemmap_remap_walk walk = {
.remap_pte = vmemmap_remap_pte,
.reuse_addr = reuse,
- .vmemmap_pages = &vmemmap_pages,
+ .vmemmap_pages = &freed_pages,
};
int nid = page_to_nid((struct page *)start);
gfp_t gfp_mask = GFP_KERNEL | __GFP_THISNODE | __GFP_NORETRY |
@@ -335,7 +338,7 @@ 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, &freed_pages);
}
/*
@@ -366,15 +369,14 @@ 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 = &freed_pages,
};
vmemmap_remap_range(reuse, end, &walk);
}
mmap_read_unlock(&init_mm);
- free_vmemmap_page_list(&vmemmap_pages);
-
+ list_splice(&freed_pages, vmemmap_pages);
return ret;
}
@@ -553,17 +555,9 @@ 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 void __hugetlb_vmemmap_optimize(const struct hstate *h,
+ struct page *head,
+ struct list_head *vmemmap_pages)
{
unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
unsigned long vmemmap_reuse;
@@ -580,21 +574,43 @@ 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))
+ if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse, vmemmap_pages))
static_branch_dec(&hugetlb_optimize_vmemmap_key);
else
SetHPageVmemmapOptimized(head);
}
+/**
+ * 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);
+ __hugetlb_vmemmap_optimize(h, &folio->page, &vmemmap_pages);
+
+ free_vmemmap_page_list(&vmemmap_pages);
}
static struct ctl_table hugetlb_vmemmap_sysctls[] = {
