diff options
Diffstat (limited to 'mm/ksm.c')
| -rw-r--r-- | mm/ksm.c | 172 |
1 files changed, 157 insertions, 15 deletions
@@ -196,6 +196,13 @@ static DECLARE_WAIT_QUEUE_HEAD(ksm_thread_wait); static DEFINE_MUTEX(ksm_thread_mutex); static DEFINE_SPINLOCK(ksm_mmlist_lock); +/* + * Temporary hack for page_referenced_ksm() and try_to_unmap_ksm(), + * later we rework things a little to get the right vma to them. + */ +static DEFINE_SPINLOCK(ksm_fallback_vma_lock); +static struct vm_area_struct ksm_fallback_vma; + #define KSM_KMEM_CACHE(__struct, __flags) kmem_cache_create("ksm_"#__struct,\ sizeof(struct __struct), __alignof__(struct __struct),\ (__flags), NULL) @@ -445,14 +452,20 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item) { if (rmap_item->address & STABLE_FLAG) { struct stable_node *stable_node; + struct page *page; stable_node = rmap_item->head; + page = stable_node->page; + lock_page(page); + hlist_del(&rmap_item->hlist); - if (stable_node->hlist.first) + if (stable_node->hlist.first) { + unlock_page(page); ksm_pages_sharing--; - else { - set_page_stable_node(stable_node->page, NULL); - put_page(stable_node->page); + } else { + set_page_stable_node(page, NULL); + unlock_page(page); + put_page(page); rb_erase(&stable_node->node, &root_stable_tree); free_stable_node(stable_node); @@ -710,7 +723,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, } get_page(kpage); - page_add_ksm_rmap(kpage); + page_add_anon_rmap(kpage, vma, addr); flush_cache_page(vma, addr, pte_pfn(*ptep)); ptep_clear_flush(vma, addr, ptep); @@ -763,8 +776,16 @@ static int try_to_merge_one_page(struct vm_area_struct *vma, pages_identical(page, kpage)) err = replace_page(vma, page, kpage, orig_pte); - if ((vma->vm_flags & VM_LOCKED) && !err) + if ((vma->vm_flags & VM_LOCKED) && !err) { munlock_vma_page(page); + if (!PageMlocked(kpage)) { + unlock_page(page); + lru_add_drain(); + lock_page(kpage); + mlock_vma_page(kpage); + page = kpage; /* for final unlock */ + } + } unlock_page(page); out: @@ -841,7 +862,11 @@ static struct page *try_to_merge_two_pages(struct rmap_item *rmap_item, copy_user_highpage(kpage, page, rmap_item->address, vma); + SetPageDirty(kpage); + __SetPageUptodate(kpage); + SetPageSwapBacked(kpage); set_page_stable_node(kpage, NULL); /* mark it PageKsm */ + lru_cache_add_lru(kpage, LRU_ACTIVE_ANON); err = try_to_merge_one_page(vma, page, kpage); up: @@ -1071,7 +1096,9 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) * The page was successfully merged: * add its rmap_item to the stable tree. */ + lock_page(kpage); stable_tree_append(rmap_item, stable_node); + unlock_page(kpage); } put_page(kpage); return; @@ -1112,11 +1139,13 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) if (kpage) { remove_rmap_item_from_tree(tree_rmap_item); + lock_page(kpage); stable_node = stable_tree_insert(kpage); if (stable_node) { stable_tree_append(tree_rmap_item, stable_node); stable_tree_append(rmap_item, stable_node); } + unlock_page(kpage); put_page(kpage); /* @@ -1285,14 +1314,6 @@ static void ksm_do_scan(unsigned int scan_npages) return; if (!PageKsm(page) || !in_stable_tree(rmap_item)) cmp_and_merge_page(page, rmap_item); - else if (page_mapcount(page) == 1) { - /* - * Replace now-unshared ksm page by ordinary page. - */ - break_cow(rmap_item); - remove_rmap_item_from_tree(rmap_item); - rmap_item->oldchecksum = calc_checksum(page); - } put_page(page); } } @@ -1337,7 +1358,7 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start, if (*vm_flags & (VM_MERGEABLE | VM_SHARED | VM_MAYSHARE | VM_PFNMAP | VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | - VM_MIXEDMAP | VM_SAO)) + VM_NONLINEAR | VM_MIXEDMAP | VM_SAO)) return 0; /* just ignore the advice */ if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) { @@ -1435,6 +1456,127 @@ void __ksm_exit(struct mm_struct *mm) } } +struct page *ksm_does_need_to_copy(struct page *page, + struct vm_area_struct *vma, unsigned long address) +{ + struct page *new_page; + + unlock_page(page); /* any racers will COW it, not modify it */ + + new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); + if (new_page) { + copy_user_highpage(new_page, page, address, vma); + + SetPageDirty(new_page); + __SetPageUptodate(new_page); + SetPageSwapBacked(new_page); + __set_page_locked(new_page); + + if (page_evictable(new_page, vma)) + lru_cache_add_lru(new_page, LRU_ACTIVE_ANON); + else + add_page_to_unevictable_list(new_page); + } + + page_cache_release(page); + return new_page; +} + +int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg, + unsigned long *vm_flags) +{ + struct stable_node *stable_node; + struct rmap_item *rmap_item; + struct hlist_node *hlist; + unsigned int mapcount = page_mapcount(page); + int referenced = 0; + struct vm_area_struct *vma; + + VM_BUG_ON(!PageKsm(page)); + VM_BUG_ON(!PageLocked(page)); + + stable_node = page_stable_node(page); + if (!stable_node) + return 0; + + /* + * Temporary hack: really we need anon_vma in rmap_item, to + * provide the correct vma, and to find recently forked instances. + * Use zalloc to avoid weirdness if any other fields are involved. + */ + vma = kmem_cache_zalloc(vm_area_cachep, GFP_ATOMIC); + if (!vma) { + spin_lock(&ksm_fallback_vma_lock); + vma = &ksm_fallback_vma; + } + + hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) { + if (memcg && !mm_match_cgroup(rmap_item->mm, memcg)) + continue; + + vma->vm_mm = rmap_item->mm; + vma->vm_start = rmap_item->address; + vma->vm_end = vma->vm_start + PAGE_SIZE; + + referenced += page_referenced_one(page, vma, + rmap_item->address, &mapcount, vm_flags); + if (!mapcount) + goto out; + } +out: + if (vma == &ksm_fallback_vma) + spin_unlock(&ksm_fallback_vma_lock); + else + kmem_cache_free(vm_area_cachep, vma); + return referenced; +} + +int try_to_unmap_ksm(struct page *page, enum ttu_flags flags) +{ + struct stable_node *stable_node; + struct hlist_node *hlist; + struct rmap_item *rmap_item; + int ret = SWAP_AGAIN; + struct vm_area_struct *vma; + + VM_BUG_ON(!PageKsm(page)); + VM_BUG_ON(!PageLocked(page)); + + stable_node = page_stable_node(page); + if (!stable_node) + return SWAP_FAIL; + + /* + * Temporary hack: really we need anon_vma in rmap_item, to + * provide the correct vma, and to find recently forked instances. + * Use zalloc to avoid weirdness if any other fields are involved. + */ + if (TTU_ACTION(flags) != TTU_UNMAP) + return SWAP_FAIL; + + vma = kmem_cache_zalloc(vm_area_cachep, GFP_ATOMIC); + if (!vma) { + spin_lock(&ksm_fallback_vma_lock); + vma = &ksm_fallback_vma; + } + + hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) { + vma->vm_mm = rmap_item->mm; + vma->vm_start = rmap_item->address; + vma->vm_end = vma->vm_start + PAGE_SIZE; + + ret = try_to_unmap_one(page, vma, rmap_item->address, flags); + if (ret != SWAP_AGAIN || !page_mapped(page)) + goto out; + } +out: + if (vma == &ksm_fallback_vma) + spin_unlock(&ksm_fallback_vma_lock); + else + kmem_cache_free(vm_area_cachep, vma); + return ret; +} + #ifdef CONFIG_SYSFS /* * This all compiles without CONFIG_SYSFS, but is a waste of space. |