From riel@redhat.com Tue Dec 18 13:20:52 2007 Date: Tue, 18 Dec 2007 16:15:44 -0500 From: Rik van Riel To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, lee.shermerhorn@hp.com, Lee Schermerhorn Subject: [patch 05/20] define page_file_cache() function Define page_file_cache() function to answer the question: is page backed by a file? Originally part of Rik van Riel's split-lru patch. Extracted to make available for other, independent reclaim patches. Moved inline function to linux/mm_inline.h where it will be needed by subsequent "split LRU" and "noreclaim" patches. Unfortunately this needs to use a page flag, since the PG_swapbacked state needs to be preserved all the way to the point where the page is last removed from the LRU. Trying to derive the status from other info in the page resulted in wrong VM statistics in earlier split VM patchsets. Signed-off-by: Rik van Riel Signed-off-by: Lee Schermerhorn Index: linux-2.6.24-rc3-mm2/include/linux/mm_inline.h =================================================================== --- linux-2.6.24-rc3-mm2.orig/include/linux/mm_inline.h +++ linux-2.6.24-rc3-mm2/include/linux/mm_inline.h @@ -1,3 +1,24 @@ +#ifndef LINUX_MM_INLINE_H +#define LINUX_MM_INLINE_H + +/** + * page_file_cache(@page) + * Returns !0 if @page is page cache page backed by a regular filesystem, + * or 0 if @page is anonymous, tmpfs or otherwise ram or swap backed. + * + * We would like to get this info without a page flag, but the state + * needs to survive until the page is last deleted from the LRU, which + * could be as far down as __page_cache_release. + */ +static inline int page_file_cache(struct page *page) +{ + if (PageSwapBacked(page)) + return 0; + + /* The page is page cache backed by a normal filesystem. */ + return 2; +} + static inline void add_page_to_active_list(struct zone *zone, struct page *page) { @@ -38,3 +59,4 @@ del_page_from_lru(struct zone *zone, str } } +#endif Index: linux-2.6.24-rc3-mm2/mm/shmem.c =================================================================== --- linux-2.6.24-rc3-mm2.orig/mm/shmem.c +++ linux-2.6.24-rc3-mm2/mm/shmem.c @@ -1279,6 +1279,7 @@ repeat: goto failed; } + SetPageSwapBacked(filepage); spin_lock(&info->lock); entry = shmem_swp_alloc(info, idx, sgp); if (IS_ERR(entry)) Index: linux-2.6.24-rc3-mm2/include/linux/page-flags.h =================================================================== --- linux-2.6.24-rc3-mm2.orig/include/linux/page-flags.h +++ linux-2.6.24-rc3-mm2/include/linux/page-flags.h @@ -89,6 +89,7 @@ #define PG_mappedtodisk 16 /* Has blocks allocated on-disk */ #define PG_reclaim 17 /* To be reclaimed asap */ #define PG_buddy 19 /* Page is free, on buddy lists */ +#define PG_swapbacked 20 /* Page is backed by RAM/swap */ /* PG_readahead is only used for file reads; PG_reclaim is only for writes */ #define PG_readahead PG_reclaim /* Reminder to do async read-ahead */ @@ -216,6 +217,10 @@ 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 PageSwapBacked(page) test_bit(PG_swapbacked, &(page)->flags) +#define SetPageSwapBacked(page) set_bit(PG_swapbacked, &(page)->flags) +#define __ClearPageSwapBacked(page) __clear_bit(PG_swapbacked, &(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) Index: linux-2.6.24-rc3-mm2/mm/memory.c =================================================================== --- linux-2.6.24-rc3-mm2.orig/mm/memory.c +++ linux-2.6.24-rc3-mm2/mm/memory.c @@ -1664,6 +1664,7 @@ gotten: ptep_clear_flush(vma, address, page_table); set_pte_at(mm, address, page_table, entry); update_mmu_cache(vma, address, entry); + SetPageSwapBacked(new_page); lru_cache_add_active(new_page); page_add_new_anon_rmap(new_page, vma, address); @@ -2132,6 +2133,7 @@ static int do_anonymous_page(struct mm_s if (!pte_none(*page_table)) goto release; inc_mm_counter(mm, anon_rss); + SetPageSwapBacked(page); lru_cache_add_active(page); page_add_new_anon_rmap(page, vma, address); set_pte_at(mm, address, page_table, entry); @@ -2285,6 +2287,7 @@ static int __do_fault(struct mm_struct * set_pte_at(mm, address, page_table, entry); if (anon) { inc_mm_counter(mm, anon_rss); + SetPageSwapBacked(page); lru_cache_add_active(page); page_add_new_anon_rmap(page, vma, address); } else { Index: linux-2.6.24-rc3-mm2/mm/swap_state.c =================================================================== --- linux-2.6.24-rc3-mm2.orig/mm/swap_state.c +++ linux-2.6.24-rc3-mm2/mm/swap_state.c @@ -86,6 +86,7 @@ static int __add_to_swap_cache(struct pa if (!error) { page_cache_get(page); SetPageSwapCache(page); + SetPageSwapBacked(page); set_page_private(page, entry.val); total_swapcache_pages++; __inc_zone_page_state(page, NR_FILE_PAGES); Index: linux-2.6.24-rc3-mm2/mm/migrate.c =================================================================== --- linux-2.6.24-rc3-mm2.orig/mm/migrate.c +++ linux-2.6.24-rc3-mm2/mm/migrate.c @@ -546,6 +546,8 @@ static int move_to_new_page(struct page /* Prepare mapping for the new page.*/ newpage->index = page->index; newpage->mapping = page->mapping; + if (PageSwapBacked(page)) + SetPageSwapBacked(newpage); mapping = page_mapping(page); if (!mapping) Index: linux-2.6.24-rc3-mm2/mm/page_alloc.c =================================================================== --- linux-2.6.24-rc3-mm2.orig/mm/page_alloc.c +++ linux-2.6.24-rc3-mm2/mm/page_alloc.c @@ -253,6 +253,7 @@ static void bad_page(struct page *page) 1 << PG_slab | 1 << PG_swapcache | 1 << PG_writeback | + 1 << PG_swapbacked | 1 << PG_buddy ); set_page_count(page, 0); reset_page_mapcount(page); @@ -486,6 +487,8 @@ static inline int free_pages_check(struc bad_page(page); if (PageDirty(page)) __ClearPageDirty(page); + if (PageSwapBacked(page)) + __ClearPageSwapBacked(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 @@ -632,6 +635,7 @@ static int prep_new_page(struct page *pa 1 << PG_swapcache | 1 << PG_writeback | 1 << PG_reserved | + 1 << PG_swapbacked | 1 << PG_buddy )))) bad_page(page); -- All Rights Reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org