On 2023/8/26 03:04, Mike Kravetz wrote:
At the beginning of hugetlb_vmemmap_optimize, optimistically set
the HPageVmemmapOptimized flag in the head page. Clear the flag
if the operation fails.
No change in behavior. However, this will become important in
subsequent patches where we batch delay TLB flushing. We need to
make sure the content in the old and new vmemmap pages are the same.
Sorry, I didn't get the point here. Could you elaborate it?
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
mm/hugetlb_vmemmap.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index e390170c0887..500a118915ff 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -566,7 +566,9 @@ static void __hugetlb_vmemmap_optimize(const struct hstate *h,
if (!vmemmap_should_optimize(h, head))
return;
+ /* Optimistically assume success */
static_branch_inc(&hugetlb_optimize_vmemmap_key);
+ SetHPageVmemmapOptimized(head);
vmemmap_end = vmemmap_start + hugetlb_vmemmap_size(h);
vmemmap_reuse = vmemmap_start;
@@ -577,10 +579,10 @@ static void __hugetlb_vmemmap_optimize(const struct hstate *h,
* to the page which @vmemmap_reuse is mapped to, then free the pages
* which the range [@vmemmap_start, @vmemmap_end] is mapped to.
*/
- if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse, bulk_pages))
+ if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse, bulk_pages)) {
static_branch_dec(&hugetlb_optimize_vmemmap_key);
- else
- SetHPageVmemmapOptimized(head);
+ ClearHPageVmemmapOptimized(head);
+ }
}
/**
