The patch titled
Subject: hugetlb: batch TLB flushes when restoring vmemmap
has been added to the -mm mm-unstable branch. Its filename is
hugetlb-batch-tlb-flushes-when-restoring-vmemmap.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hugetlb-batch-tlb-flushes-when-restoring-vmemmap.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Subject: hugetlb: batch TLB flushes when restoring vmemmap
Date: Mon, 25 Sep 2023 16:48:36 -0700
Update the internal hugetlb restore vmemmap code path such that TLB
flushing can be batched. Use the existing mechanism of passing the
VMEMMAP_REMAP_NO_TLB_FLUSH flag to indicate flushing should not be
performed for individual pages. The routine
hugetlb_vmemmap_restore_folios is the only user of this new mechanism, and
it will perform a global flush after all vmemmap is restored.
Link: https://lkml.kernel.org/r/20230925234837.86786-9-mike.kravetz@xxxxxxxxxx
Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: James Houghton <jthoughton@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb_vmemmap.c | 39 ++++++++++++++++++++++++---------------
1 file changed, 24 insertions(+), 15 deletions(-)
--- a/mm/hugetlb_vmemmap.c~hugetlb-batch-tlb-flushes-when-restoring-vmemmap
+++ a/mm/hugetlb_vmemmap.c
@@ -461,18 +461,19 @@ out:
* @end: end address of the vmemmap virtual address range that we want to
* remap.
* @reuse: reuse address.
+ * @flags: modifications to vmemmap_remap_walk flags
*
* 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 = 0,
+ .flags = flags,
};
/* See the comment in the vmemmap_remap_free(). */
@@ -494,17 +495,7 @@ EXPORT_SYMBOL(hugetlb_optimize_vmemmap_k
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;
@@ -525,7 +516,7 @@ int hugetlb_vmemmap_restore(const struct
* 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);
@@ -535,6 +526,21 @@ int hugetlb_vmemmap_restore(const struct
}
/**
+ * 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, 0);
+}
+
+/**
* hugetlb_vmemmap_restore_folios - restore vmemmap for every folio on the list.
* @h: hstate.
* @folio_list: list of folios.
@@ -557,7 +563,8 @@ long hugetlb_vmemmap_restore_folios(cons
list_for_each_entry_safe(folio, t_folio, folio_list, lru) {
if (folio_test_hugetlb_vmemmap_optimized(folio)) {
- ret = hugetlb_vmemmap_restore(h, &folio->page);
+ ret = __hugetlb_vmemmap_restore(h, &folio->page,
+ VMEMMAP_REMAP_NO_TLB_FLUSH);
if (ret)
break;
restored++;
@@ -567,6 +574,8 @@ long hugetlb_vmemmap_restore_folios(cons
list_move(&folio->lru, non_hvo_folios);
}
+ if (restored)
+ flush_tlb_all();
if (!ret)
ret = restored;
return ret;
_
Patches currently in -mm which might be from mike.kravetz@xxxxxxxxxx are
hugetlb-set-hugetlb-page-flag-before-optimizing-vmemmap.patch
hugetlb-optimize-update_and_free_pages_bulk-to-avoid-lock-cycles.patch
hugetlb-restructure-pool-allocations.patch
hugetlb-perform-vmemmap-optimization-on-a-list-of-pages.patch
hugetlb-perform-vmemmap-restoration-on-a-list-of-pages.patch
hugetlb-batch-freeing-of-vmemmap-pages.patch
hugetlb-batch-tlb-flushes-when-restoring-vmemmap.patch
