diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 33a5dc492810..51f069303ab9 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1243,6 +1243,10 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) return ERR_PTR(-EFAULT); + /* Full NUMA hinting faults to serialise migration in fault paths */ + if ((flags & FOLL_NUMA) && pmd_numa(*pmd)) + goto out; + page = pmd_page(*pmd); VM_BUG_ON(!PageHead(page)); if (flags & FOLL_TOUCH) { @@ -1323,23 +1327,27 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, /* If the page was locked, there are no parallel migrations */ if (page_locked) goto clear_pmdnuma; + } - /* - * Otherwise wait for potential migrations and retry. We do - * relock and check_same as the page may no longer be mapped. - * As the fault is being retried, do not account for it. - */ + /* + * If there are potential migrations, wait for completion and retry. We + * do not relock and check_same as the page may no longer be mapped. + * Furtermore, even if the page is currently misplaced, there is no + * guarantee it is still misplaced after the migration completes. + */ + if (!page_locked) { spin_unlock(ptl); wait_on_page_locked(page); page_nid = -1; goto out; } - /* Page is misplaced, serialise migrations and parallel THP splits */ + /* + * Page is misplaced. Page lock serialises migrations. Acquire anon_vma + * to serialises splits + */ get_page(page); spin_unlock(ptl); - if (!page_locked) - lock_page(page); anon_vma = page_lock_anon_vma_read(page); /* Confirm the PMD did not change while page_table_lock was released */ |