--- linux-2.6.21-rc6-mm1/include/asm-parisc/mman.h.madv_free 2007-04-17 02:17:19.000000000 -0400 +++ linux-2.6.21-rc6-mm1/include/asm-parisc/mman.h 2007-04-17 02:22:46.000000000 -0400 @@ -38,6 +38,7 @@ #define MADV_SPACEAVAIL 5 /* insure that resources are reserved */ #define MADV_VPS_PURGE 6 /* Purge pages from VM page cache */ #define MADV_VPS_INHERIT 7 /* Inherit parents page size */ +#define MADV_FREE 8 /* don't need the pages or the data */ /* common/generic parameters */ #define MADV_REMOVE 9 /* remove these pages & resources */ --- linux-2.6.21-rc6-mm1/include/asm-mips/mman.h.madv_free 2007-04-17 02:17:19.000000000 -0400 +++ linux-2.6.21-rc6-mm1/include/asm-mips/mman.h 2007-04-17 02:22:46.000000000 -0400 @@ -65,6 +65,7 @@ #define MADV_SEQUENTIAL 2 /* expect sequential page references */ #define MADV_WILLNEED 3 /* will need these pages */ #define MADV_DONTNEED 4 /* don't need these pages */ +#define MADV_FREE 5 /* don't need the pages or the data */ /* common parameters: try to keep these consistent across architectures */ #define MADV_REMOVE 9 /* remove these pages & resources */ --- linux-2.6.21-rc6-mm1/include/asm-xtensa/mman.h.madv_free 2007-04-17 02:17:19.000000000 -0400 +++ linux-2.6.21-rc6-mm1/include/asm-xtensa/mman.h 2007-04-17 02:22:46.000000000 -0400 @@ -72,6 +72,7 @@ #define MADV_SEQUENTIAL 2 /* expect sequential page references */ #define MADV_WILLNEED 3 /* will need these pages */ #define MADV_DONTNEED 4 /* don't need these pages */ +#define MADV_FREE 5 /* don't need the pages or the data */ /* common parameters: try to keep these consistent across architectures */ #define MADV_REMOVE 9 /* remove these pages & resources */ --- linux-2.6.21-rc6-mm1/include/linux/swap.h.madv_free 2007-04-17 02:17:43.000000000 -0400 +++ linux-2.6.21-rc6-mm1/include/linux/swap.h 2007-04-17 02:22:46.000000000 -0400 @@ -182,6 +182,7 @@ extern void FASTCALL(lru_cache_add(struc extern void FASTCALL(lru_cache_add_active(struct page *)); extern void FASTCALL(lru_cache_add_tail(struct page *)); extern void FASTCALL(activate_page(struct page *)); +extern void FASTCALL(deactivate_tail_page(struct page *)); extern void FASTCALL(mark_page_accessed(struct page *)); extern void lru_add_drain(void); extern int lru_add_drain_all(void); --- linux-2.6.21-rc6-mm1/include/linux/mm.h.madv_free 2007-04-17 02:17:43.000000000 -0400 +++ linux-2.6.21-rc6-mm1/include/linux/mm.h 2007-04-17 02:22:46.000000000 -0400 @@ -767,6 +767,7 @@ struct zap_details { pgoff_t last_index; /* Highest page->index to unmap */ spinlock_t *i_mmap_lock; /* For unmap_mapping_range: */ unsigned long truncate_count; /* Compare vm_truncate_count */ + short madv_free; /* MADV_FREE anonymous memory */ }; struct page *vm_normal_page(struct vm_area_struct *, unsigned long, pte_t); --- linux-2.6.21-rc6-mm1/include/linux/page-flags.h.madv_free 2007-04-17 02:17:43.000000000 -0400 +++ linux-2.6.21-rc6-mm1/include/linux/page-flags.h 2007-04-17 02:23:16.000000000 -0400 @@ -91,6 +91,7 @@ #define PG_booked 20 /* Has blocks reserved on-disk */ #define PG_readahead 21 /* Reminder to do read-ahead */ +#define PG_lazyfree 22 /* MADV_FREE potential throwaway */ /* PG_owner_priv_1 users should have descriptive aliases */ #define PG_checked PG_owner_priv_1 /* Used by some filesystems */ @@ -216,6 +217,11 @@ static inline void SetPageUptodate(struc #define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags) #define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags) +#define PageLazyFree(page) test_bit(PG_lazyfree, &(page)->flags) +#define SetPageLazyFree(page) set_bit(PG_lazyfree, &(page)->flags) +#define ClearPageLazyFree(page) clear_bit(PG_lazyfree, &(page)->flags) +#define __ClearPageLazyFree(page) __clear_bit(PG_lazyfree, &(page)->flags) + #define PageCompound(page) test_bit(PG_compound, &(page)->flags) #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags) #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags) --- linux-2.6.21-rc6-mm1/include/asm-alpha/mman.h.madv_free 2007-04-17 02:17:19.000000000 -0400 +++ linux-2.6.21-rc6-mm1/include/asm-alpha/mman.h 2007-04-17 02:22:46.000000000 -0400 @@ -42,6 +42,7 @@ #define MADV_WILLNEED 3 /* will need these pages */ #define MADV_SPACEAVAIL 5 /* ensure resources are available */ #define MADV_DONTNEED 6 /* don't need these pages */ +#define MADV_FREE 7 /* don't need the pages or the data */ /* common/generic parameters */ #define MADV_REMOVE 9 /* remove these pages & resources */ --- linux-2.6.21-rc6-mm1/include/asm-generic/mman.h.madv_free 2007-04-17 02:17:19.000000000 -0400 +++ linux-2.6.21-rc6-mm1/include/asm-generic/mman.h 2007-04-17 02:22:46.000000000 -0400 @@ -29,6 +29,7 @@ #define MADV_SEQUENTIAL 2 /* expect sequential page references */ #define MADV_WILLNEED 3 /* will need these pages */ #define MADV_DONTNEED 4 /* don't need these pages */ +#define MADV_FREE 5 /* don't need the pages or the data */ /* common parameters: try to keep these consistent across architectures */ #define MADV_REMOVE 9 /* remove these pages & resources */ --- linux-2.6.21-rc6-mm1/mm/memory.c.madv_free 2007-04-17 02:17:43.000000000 -0400 +++ linux-2.6.21-rc6-mm1/mm/memory.c 2007-04-17 02:22:46.000000000 -0400 @@ -432,6 +432,7 @@ copy_one_pte(struct mm_struct *dst_mm, s unsigned long vm_flags = vma->vm_flags; pte_t pte = *src_pte; struct page *page; + int dirty = 0; /* pte contains position in swap or file, so copy. */ if (unlikely(!pte_present(pte))) { @@ -466,6 +467,7 @@ copy_one_pte(struct mm_struct *dst_mm, s * in the parent and the child */ if (is_cow_mapping(vm_flags)) { + dirty = pte_dirty(pte); ptep_set_wrprotect(src_mm, addr, src_pte); pte = pte_wrprotect(pte); } @@ -483,6 +485,8 @@ copy_one_pte(struct mm_struct *dst_mm, s get_page(page); page_dup_rmap(page, vma, addr); rss[!!PageAnon(page)]++; + if (dirty && PageLazyFree(page)) + ClearPageLazyFree(page); } out_set_pte: @@ -661,6 +665,25 @@ static unsigned long zap_pte_range(struc (page->index < details->first_index || page->index > details->last_index)) continue; + + /* + * MADV_FREE is used to lazily recycle + * anon memory. The process no longer + * needs the data and wants to avoid IO. + */ + if (details->madv_free && PageAnon(page)) { + if (unlikely(PageSwapCache(page)) && + !TestSetPageLocked(page)) { + remove_exclusive_swap_page(page); + unlock_page(page); + } + ptep_clear_flush_dirty(vma, addr, pte); + ptep_clear_flush_young(vma, addr, pte); + SetPageLazyFree(page); + if (PageActive(page)) + deactivate_tail_page(page); + continue; + } } ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); @@ -689,7 +713,8 @@ static unsigned long zap_pte_range(struc * If details->check_mapping, we leave swap entries; * if details->nonlinear_vma, we leave file entries. */ - if (unlikely(details)) + if (unlikely(details && (details->check_mapping || + details->nonlinear_vma))) continue; if (!pte_file(ptent)) free_swap_and_cache(pte_to_swp_entry(ptent)); @@ -755,7 +780,8 @@ static unsigned long unmap_page_range(st pgd_t *pgd; unsigned long next; - if (details && !details->check_mapping && !details->nonlinear_vma) + if (details && !details->check_mapping && !details->nonlinear_vma + && !details->madv_free) details = NULL; BUG_ON(addr >= end); --- linux-2.6.21-rc6-mm1/mm/page_alloc.c.madv_free 2007-04-17 02:17:43.000000000 -0400 +++ linux-2.6.21-rc6-mm1/mm/page_alloc.c 2007-04-17 02:22:46.000000000 -0400 @@ -266,6 +266,7 @@ static void bad_page(struct page *page) 1 << PG_slab | 1 << PG_swapcache | 1 << PG_writeback | + 1 << PG_lazyfree | 1 << PG_buddy ); set_page_count(page, 0); reset_page_mapcount(page); @@ -514,6 +515,8 @@ static inline int free_pages_check(struc bad_page(page); if (PageDirty(page)) __ClearPageDirty(page); + if (PageLazyFree(page)) + __ClearPageLazyFree(page); /* * For now, we report if PG_reserved was found set, but do not * clear it, and do not free the page. But we shall soon need @@ -661,6 +664,7 @@ static int prep_new_page(struct page *pa 1 << PG_swapcache | 1 << PG_writeback | 1 << PG_reserved | + 1 << PG_lazyfree | 1 << PG_buddy )))) bad_page(page); --- linux-2.6.21-rc6-mm1/mm/swap.c.madv_free 2007-04-17 02:17:43.000000000 -0400 +++ linux-2.6.21-rc6-mm1/mm/swap.c 2007-04-17 02:22:46.000000000 -0400 @@ -152,6 +152,20 @@ void fastcall activate_page(struct page spin_unlock_irq(&zone->lru_lock); } +void fastcall deactivate_tail_page(struct page *page) +{ + struct zone *zone = page_zone(page); + + spin_lock_irq(&zone->lru_lock); + if (PageLRU(page) && PageActive(page)) { + del_page_from_active_list(zone, page); + ClearPageActive(page); + add_page_to_inactive_list_tail(zone, page); + __count_vm_event(PGDEACTIVATE); + } + spin_unlock_irq(&zone->lru_lock); +} + /* * Mark a page as having seen activity. * --- linux-2.6.21-rc6-mm1/mm/vmscan.c.madv_free 2007-04-17 02:17:43.000000000 -0400 +++ linux-2.6.21-rc6-mm1/mm/vmscan.c 2007-04-17 02:22:46.000000000 -0400 @@ -460,6 +460,24 @@ static unsigned long shrink_page_list(st sc->nr_scanned++; + /* + * MADV_DONTNEED pages get reclaimed lazily, unless the + * process reuses it before we get to it. + */ + if (PageLazyFree(page)) { + switch (try_to_unmap(page, 0)) { + case SWAP_FAIL: + ClearPageLazyFree(page); + goto activate_locked; + case SWAP_AGAIN: + ClearPageLazyFree(page); + goto keep_locked; + case SWAP_SUCCESS: + ClearPageLazyFree(page); + goto free_it; + } + } + if (!sc->may_swap && page_mapped(page)) goto keep_locked; --- linux-2.6.21-rc6-mm1/mm/madvise.c.madv_free 2007-04-17 02:17:20.000000000 -0400 +++ linux-2.6.21-rc6-mm1/mm/madvise.c 2007-04-17 02:22:46.000000000 -0400 @@ -142,8 +142,12 @@ static long madvise_dontneed(struct vm_a .last_index = ULONG_MAX, }; zap_page_range(vma, start, end - start, &details); - } else - zap_page_range(vma, start, end - start, NULL); + } else { + struct zap_details details = { + .madv_free = 1, + }; + zap_page_range(vma, start, end - start, &details); + } return 0; } @@ -215,7 +219,9 @@ madvise_vma(struct vm_area_struct *vma, error = madvise_willneed(vma, prev, start, end); break; + /* FIXME: POSIX says that MADV_DONTNEED cannot throw away data. */ case MADV_DONTNEED: + case MADV_FREE: error = madvise_dontneed(vma, prev, start, end); break; --- linux-2.6.21-rc6-mm1/mm/rmap.c.madv_free 2007-04-17 02:17:43.000000000 -0400 +++ linux-2.6.21-rc6-mm1/mm/rmap.c 2007-04-17 02:22:46.000000000 -0400 @@ -707,7 +707,17 @@ static int try_to_unmap_one(struct page /* Update high watermark before we lower rss */ update_hiwater_rss(mm); - if (PageAnon(page)) { + /* MADV_FREE is used to lazily free memory from userspace. */ + if (PageLazyFree(page) && !migration) { + /* There is new data in the page. Reinstate it. */ + if (unlikely(pte_dirty(pteval))) { + set_pte_at(mm, address, pte, pteval); + ret = SWAP_FAIL; + goto out_unmap; + } + /* Throw the page away. */ + dec_mm_counter(mm, anon_rss); + } else if (PageAnon(page)) { swp_entry_t entry = { .val = page_private(page) }; if (PageSwapCache(page)) {