diff options
| -rw-r--r-- | mm/migrate.c | 141 |
1 files changed, 112 insertions, 29 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 991e8886093f..652b2c642eed 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2149,7 +2149,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, struct migrate_vma *migrate = walk->private; struct vm_area_struct *vma = walk->vma; struct mm_struct *mm = vma->vm_mm; - unsigned long addr = start; + unsigned long addr = start, unmapped = 0; spinlock_t *ptl; pte_t *ptep; @@ -2194,9 +2194,12 @@ again: return migrate_vma_collect_hole(start, end, walk); ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); + arch_enter_lazy_mmu_mode(); + for (; addr < end; addr += PAGE_SIZE, ptep++) { unsigned long mpfn, pfn; struct page *page; + swp_entry_t entry; pte_t pte; pte = *ptep; @@ -2228,11 +2231,44 @@ again: mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE; mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; + /* + * Optimize for the common case where page is only mapped once + * in one process. If we can lock the page, then we can safely + * set up a special migration page table entry now. + */ + if (trylock_page(page)) { + pte_t swp_pte; + + mpfn |= MIGRATE_PFN_LOCKED; + ptep_get_and_clear(mm, addr, ptep); + + /* Setup special migration page table entry */ + entry = make_migration_entry(page, pte_write(pte)); + swp_pte = swp_entry_to_pte(entry); + if (pte_soft_dirty(pte)) + swp_pte = pte_swp_mksoft_dirty(swp_pte); + set_pte_at(mm, addr, ptep, swp_pte); + + /* + * This is like regular unmap: we remove the rmap and + * drop page refcount. Page won't be freed, as we took + * a reference just above. + */ + page_remove_rmap(page, false); + put_page(page); + unmapped++; + } + next: migrate->src[migrate->npages++] = mpfn; } + arch_leave_lazy_mmu_mode(); pte_unmap_unlock(ptep - 1, ptl); + /* Only flush the TLB if we actually modified any entries */ + if (unmapped) + flush_tlb_range(walk->vma, start, end); + return 0; } @@ -2257,7 +2293,13 @@ static void migrate_vma_collect(struct migrate_vma *migrate) mm_walk.mm = migrate->vma->vm_mm; mm_walk.private = migrate; + mmu_notifier_invalidate_range_start(mm_walk.mm, + migrate->start, + migrate->end); walk_page_range(migrate->start, migrate->end, &mm_walk); + mmu_notifier_invalidate_range_end(mm_walk.mm, + migrate->start, + migrate->end); migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT); } @@ -2305,32 +2347,37 @@ static bool migrate_vma_check_page(struct page *page) static void migrate_vma_prepare(struct migrate_vma *migrate) { const unsigned long npages = migrate->npages; + const unsigned long start = migrate->start; + unsigned long addr, i, restore = 0; bool allow_drain = true; - unsigned long i; lru_add_drain(); for (i = 0; (i < npages) && migrate->cpages; i++) { struct page *page = migrate_pfn_to_page(migrate->src[i]); + bool remap = true; if (!page) continue; - /* - * Because we are migrating several pages there can be - * a deadlock between 2 concurrent migration where each - * are waiting on each other page lock. - * - * Make migrate_vma() a best effort thing and backoff - * for any page we can not lock right away. - */ - if (!trylock_page(page)) { - migrate->src[i] = 0; - migrate->cpages--; - put_page(page); - continue; + if (!(migrate->src[i] & MIGRATE_PFN_LOCKED)) { + /* + * Because we are migrating several pages there can be + * a deadlock between 2 concurrent migration where each + * are waiting on each other page lock. + * + * Make migrate_vma() a best effort thing and backoff + * for any page we can not lock right away. + */ + if (!trylock_page(page)) { + migrate->src[i] = 0; + migrate->cpages--; + put_page(page); + continue; + } + remap = false; + migrate->src[i] |= MIGRATE_PFN_LOCKED; } - migrate->src[i] |= MIGRATE_PFN_LOCKED; if (!PageLRU(page) && allow_drain) { /* Drain CPU's pagevec */ @@ -2339,21 +2386,50 @@ static void migrate_vma_prepare(struct migrate_vma *migrate) } if (isolate_lru_page(page)) { - migrate->src[i] = 0; - unlock_page(page); - migrate->cpages--; - put_page(page); + if (remap) { + migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; + migrate->cpages--; + restore++; + } else { + migrate->src[i] = 0; + unlock_page(page); + migrate->cpages--; + put_page(page); + } continue; } if (!migrate_vma_check_page(page)) { - migrate->src[i] = 0; - unlock_page(page); - migrate->cpages--; + if (remap) { + migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; + migrate->cpages--; + restore++; - putback_lru_page(page); + get_page(page); + putback_lru_page(page); + } else { + migrate->src[i] = 0; + unlock_page(page); + migrate->cpages--; + + putback_lru_page(page); + } } } + + for (i = 0, addr = start; i < npages && restore; i++, addr += PAGE_SIZE) { + struct page *page = migrate_pfn_to_page(migrate->src[i]); + + if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE)) + continue; + + remove_migration_pte(page, migrate->vma, addr, page); + + migrate->src[i] = 0; + unlock_page(page); + put_page(page); + restore--; + } } /* @@ -2380,12 +2456,19 @@ static void migrate_vma_unmap(struct migrate_vma *migrate) if (!page || !(migrate->src[i] & MIGRATE_PFN_MIGRATE)) continue; - try_to_unmap(page, flags); - if (page_mapped(page) || !migrate_vma_check_page(page)) { - migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; - migrate->cpages--; - restore++; + if (page_mapped(page)) { + try_to_unmap(page, flags); + if (page_mapped(page)) + goto restore; } + + if (migrate_vma_check_page(page)) + continue; + +restore: + migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; + migrate->cpages--; + restore++; } for (addr = start, i = 0; i < npages && restore; addr += PAGE_SIZE, i++) { |