To say that the PMD handling code was incorrectly transferred from autonuma
is an understatement. The intention was to handle a PMDs worth of pages
in the same fault and effectively batch the taking of the PTL and page
migration. The copied version instead has the impact of clearing a number
of pte_numa PTE entries and whether any page migration takes place depends
on racing. This just happens to work in some cases.
This patch handles pte_numa faults in batch when a pmd_numa fault is
handled. The pages are migrated if they are currently misplaced.
Essentially this is making an assumption that NUMA locality is
on a PMD boundary but that could be addressed by only setting
pmd_numa if all the pages within that PMD are on the same node
if necessary.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
mm/memory.c | 54 +++++++++++++++++++++++++++++++++++-------------------
1 file changed, 35 insertions(+), 19 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 8795a0a..a498e8d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3451,6 +3451,18 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
}
+int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
+ unsigned long addr, int current_nid)
+{
+ get_page(page);
+
+ count_vm_numa_event(NUMA_HINT_FAULTS);
+ if (current_nid == numa_node_id())
+ count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
+
+ return mpol_misplaced(page, vma, addr);
+}
+
int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
{
@@ -3473,15 +3485,11 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
if (unlikely(!pte_same(*ptep, pte)))
goto out_unlock;
- count_vm_numa_event(NUMA_HINT_FAULTS);
page = vm_normal_page(vma, addr, pte);
BUG_ON(!page);
- get_page(page);
current_nid = page_to_nid(page);
- if (current_nid == numa_node_id())
- count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
- target_nid = mpol_misplaced(page, vma, addr);
+ target_nid = numa_migrate_prep(page, vma, addr, current_nid);
if (target_nid == -1) {
/*
* Account for the fault against the current node if it not
@@ -3491,9 +3499,8 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
goto clear_pmdnuma;
}
- pte_unmap_unlock(ptep, ptl);
-
/* Migrate to the requested node */
+ pte_unmap_unlock(ptep, ptl);
newpage = migrate_misplaced_page(page, target_nid);
if (newpage)
current_nid = target_nid;
@@ -3524,7 +3531,8 @@ out_unlock:
pte_unmap_unlock(ptep, ptl);
if (page)
put_page(page);
- task_numa_fault(current_nid, 1);
+ if (current_nid != -1)
+ task_numa_fault(current_nid, 1);
return 0;
}
@@ -3539,8 +3547,6 @@ int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
spinlock_t *ptl;
bool numa = false;
int local_nid = numa_node_id();
- unsigned long nr_faults = 0;
- unsigned long nr_faults_local = 0;
spin_lock(&mm->page_table_lock);
pmd = *pmdp;
@@ -3563,7 +3569,8 @@ int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) {
pte_t pteval = *pte;
struct page *page;
- int curr_nid;
+ int curr_nid = local_nid;
+ int target_nid;
if (!pte_present(pteval))
continue;
if (addr >= vma->vm_end) {
@@ -3582,21 +3589,30 @@ int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
/* only check non-shared pages */
if (unlikely(page_mapcount(page) != 1))
continue;
- pte_unmap_unlock(pte, ptl);
- curr_nid = page_to_nid(page);
- task_numa_fault(curr_nid, 1);
+ /*
+ * Note that the NUMA fault is later accounted to either
+ * the node that is currently running or where the page is
+ * migrated to.
+ */
+ curr_nid = local_nid;
+ target_nid = numa_migrate_prep(page, vma, addr,
+ page_to_nid(page));
+ if (target_nid == -1) {
+ put_page(page);
+ continue;
+ }
- nr_faults++;
- if (curr_nid == local_nid)
- nr_faults_local++;
+ /* Migrate to the requested node */
+ pte_unmap_unlock(pte, ptl);
+ if (migrate_misplaced_page(page, target_nid))
+ curr_nid = target_nid;
+ task_numa_fault(curr_nid, 1);
pte = pte_offset_map_lock(mm, pmdp, addr, &ptl);
}
pte_unmap_unlock(orig_pte, ptl);
- count_vm_numa_events(NUMA_HINT_FAULTS, nr_faults);
- count_vm_numa_events(NUMA_HINT_FAULTS_LOCAL, nr_faults_local);
return 0;
}
--
1.7.9.2
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