Re: [PATCH 1/2] mm/numa: no task_numa_fault() call if page table is changed

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On 2024/8/8 22:21, Zi Yan wrote:
On 8 Aug 2024, at 10:14, David Hildenbrand wrote:

On 08.08.24 16:13, Zi Yan wrote:
On 8 Aug 2024, at 4:22, David Hildenbrand wrote:

On 08.08.24 05:19, Baolin Wang wrote:


...
Agreed, maybe we should simply handle that right away and replace the "goto out;" users by "return 0;".

Then, just copy the 3 LOC.

For mm/memory.c that would be:

diff --git a/mm/memory.c b/mm/memory.c
index 67496dc5064f..410ba50ca746 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5461,7 +5461,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
           if (unlikely(!pte_same(old_pte, vmf->orig_pte))) {
                  pte_unmap_unlock(vmf->pte, vmf->ptl);
-               goto out;
+               return 0;
          }
           pte = pte_modify(old_pte, vma->vm_page_prot);
@@ -5528,15 +5528,14 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
                  vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
                                                 vmf->address, &vmf->ptl);
                  if (unlikely(!vmf->pte))
-                       goto out;
+                       return 0;
                  if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
                          pte_unmap_unlock(vmf->pte, vmf->ptl);
-                       goto out;
+                       return 0;
                  }
                  goto out_map;
          }
   -out:
          if (nid != NUMA_NO_NODE)
                  task_numa_fault(last_cpupid, nid, nr_pages, flags);
          return 0;

Maybe drop this part too,

diff --git a/mm/memory.c b/mm/memory.c
index 410ba50ca746..07343c1469e0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5523,6 +5523,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
        if (!migrate_misplaced_folio(folio, vma, target_nid)) {
                nid = target_nid;
                flags |= TNF_MIGRATED;
+               goto out;
        } else {
                flags |= TNF_MIGRATE_FAIL;
                vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
@@ -5533,12 +5534,8 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
                        pte_unmap_unlock(vmf->pte, vmf->ptl);
                        return 0;
                }
-               goto out_map;
        }

-       if (nid != NUMA_NO_NODE)
-               task_numa_fault(last_cpupid, nid, nr_pages, flags);
-       return 0;
 out_map:
        /*
         * Make it present again, depending on how arch implements
@@ -5551,6 +5548,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
numa_rebuild_single_mapping(vmf, vma, vmf->address, vmf->pte,
                                            writable);
        pte_unmap_unlock(vmf->pte, vmf->ptl);
+out:
        if (nid != NUMA_NO_NODE)
                task_numa_fault(last_cpupid, nid, nr_pages, flags);
        return 0;


@@ -5552,7 +5551,9 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
                  numa_rebuild_single_mapping(vmf, vma, vmf->address, vmf->pte,
                                              writable);
          pte_unmap_unlock(vmf->pte, vmf->ptl);
-       goto out;
+       if (nid != NUMA_NO_NODE)
+               task_numa_fault(last_cpupid, nid, nr_pages, flags);
+       return 0;
   }

Looks good to me. Thanks.

Hi Andrew,

Should I resend this for an easy back porting? Or you want to fold David’s
changes in directly?

Note that I didn't touch huge_memory.c. So maybe just send a fixup on top?

Got it. The fixup is attached.

Best Regards,
Yan, Zi




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