Re: [PATCH v2 11/11] hugetlb: batch TLB flushes when restoring vmemmap

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On 2023/9/6 05:44, Mike Kravetz wrote:
Update the hugetlb_vmemmap_restore path to take a 'batch' parameter that

s/batch/flags/g

And it should be reworked since the parameter has been changed.

indicates restoration is happening on a batch of pages.  When set, use
the existing mechanism (VMEMMAP_NO_TLB_FLUSH) to delay TLB flushing.
The routine hugetlb_vmemmap_restore_folios is the only user of this new
batch parameter and it will perform a global flush after all vmemmap is
restored.

Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
  mm/hugetlb_vmemmap.c | 37 +++++++++++++++++++++++--------------
  1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 8c85e2c38538..11fda9d061eb 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -458,17 +458,19 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
   * @end:	end address of the vmemmap virtual address range that we want to
   *		remap.
   * @reuse:	reuse address.
+ * @flags:	modify behavior for bulk operations
   *
   * Return: %0 on success, negative error code otherwise.
   */
  static int vmemmap_remap_alloc(unsigned long start, unsigned long end,
-			       unsigned long reuse)
+			       unsigned long reuse, unsigned long flags)
  {
  	LIST_HEAD(vmemmap_pages);
  	struct vmemmap_remap_walk walk = {
  		.remap_pte	= vmemmap_restore_pte,
  		.reuse_addr	= reuse,
  		.vmemmap_pages	= &vmemmap_pages,
+		.flags		= flags,
  	};
/* See the comment in the vmemmap_remap_free(). */
@@ -490,17 +492,7 @@ EXPORT_SYMBOL(hugetlb_optimize_vmemmap_key);
  static bool vmemmap_optimize_enabled = IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON);
  core_param(hugetlb_free_vmemmap, vmemmap_optimize_enabled, bool, 0);
-/**
- * hugetlb_vmemmap_restore - restore previously optimized (by
- *			     hugetlb_vmemmap_optimize()) vmemmap pages which
- *			     will be reallocated and remapped.
- * @h:		struct hstate.
- * @head:	the head page whose vmemmap pages will be restored.
- *
- * Return: %0 if @head's vmemmap pages have been reallocated and remapped,
- * negative error code otherwise.
- */
-int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
+static int __hugetlb_vmemmap_restore(const struct hstate *h, struct page *head, unsigned long flags)
  {
  	int ret;
  	unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
@@ -521,7 +513,7 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
  	 * When a HugeTLB page is freed to the buddy allocator, previously
  	 * discarded vmemmap pages must be allocated and remapping.
  	 */
-	ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse);
+	ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse, flags);
  	if (!ret) {
  		ClearHPageVmemmapOptimized(head);
  		static_branch_dec(&hugetlb_optimize_vmemmap_key);
@@ -530,6 +522,21 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
  	return ret;
  }
+/**
+ * hugetlb_vmemmap_restore - restore previously optimized (by
+ *			     hugetlb_vmemmap_optimize()) vmemmap pages which
+ *			     will be reallocated and remapped.
+ * @h:		struct hstate.
+ * @head:	the head page whose vmemmap pages will be restored.
+ *
+ * Return: %0 if @head's vmemmap pages have been reallocated and remapped,
+ * negative error code otherwise.
+ */
+int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
+{
+	return __hugetlb_vmemmap_restore(h, head, 0UL);

UL suffix could be drooped.

Thanks.

+}
+
  /*
   * This function will attempt to resore vmemmap for a list of folios.  There
   * is no guarantee that restoration will be successful for all or any folios.
@@ -540,7 +547,9 @@ void hugetlb_vmemmap_restore_folios(const struct hstate *h, struct list_head *fo
  	struct folio *folio;
list_for_each_entry(folio, folio_list, lru)
-		(void)hugetlb_vmemmap_restore(h, &folio->page);
+		(void)__hugetlb_vmemmap_restore(h, &folio->page, VMEMMAP_NO_TLB_FLUSH);
+
+	flush_tlb_all();
  }
/* Return true iff a HugeTLB whose vmemmap should and can be optimized. */





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