diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 57 |
1 files changed, 47 insertions, 10 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index bccd5a628ea..7de1bf85f68 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -882,6 +882,10 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, ret = 0; goto out_unlock; } + + /* mmap_sem prevents this happening but warn if that changes */ + WARN_ON(pmd_trans_migrating(pmd)); + if (unlikely(pmd_trans_splitting(pmd))) { /* split huge page running from under us */ spin_unlock(src_ptl); @@ -1243,6 +1247,10 @@ 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) { @@ -1295,6 +1303,17 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, if (unlikely(!pmd_same(pmd, *pmdp))) goto out_unlock; + /* + * If there are potential migrations, wait for completion and retry + * without disrupting NUMA hinting information. Do not relock and + * check_same as the page may no longer be mapped. + */ + if (unlikely(pmd_trans_migrating(*pmdp))) { + spin_unlock(ptl); + wait_migrate_huge_page(vma->anon_vma, pmdp); + goto out; + } + page = pmd_page(pmd); BUG_ON(is_huge_zero_page(page)); page_nid = page_to_nid(page); @@ -1323,23 +1342,22 @@ 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. - */ + /* Migration could have started since the pmd_trans_migrating check */ + 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 */ @@ -1351,6 +1369,13 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, goto out_unlock; } + /* Bail if we fail to protect against THP splits for any reason */ + if (unlikely(!anon_vma)) { + put_page(page); + page_nid = -1; + goto clear_pmdnuma; + } + /* * Migrate the THP to the requested node, returns with page unlocked * and pmd_numa cleared. @@ -1481,8 +1506,18 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); VM_BUG_ON(!pmd_none(*new_pmd)); set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); - if (new_ptl != old_ptl) + if (new_ptl != old_ptl) { + pgtable_t pgtable; + + /* + * Move preallocated PTE page table if new_pmd is on + * different PMD page table. + */ + pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); + pgtable_trans_huge_deposit(mm, new_pmd, pgtable); + spin_unlock(new_ptl); + } spin_unlock(old_ptl); } out: @@ -1507,6 +1542,8 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, ret = 1; if (!prot_numa) { entry = pmdp_get_and_clear(mm, addr, pmd); + if (pmd_numa(entry)) + entry = pmd_mknonnuma(entry); entry = pmd_modify(entry, newprot); ret = HPAGE_PMD_NR; BUG_ON(pmd_write(entry)); @@ -1521,7 +1558,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, */ if (!is_huge_zero_page(page) && !pmd_numa(*pmd)) { - entry = pmdp_get_and_clear(mm, addr, pmd); + entry = *pmd; entry = pmd_mknuma(entry); ret = HPAGE_PMD_NR; } |