X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=blobdiff_plain;f=mm%2Fswap_state.c;h=6d1daeb1cb4a3dfbcf522919312a67f861085b74;hp=67daecb6031ad62022fbe7aa7fe9ea7b027dd3cf;hb=f653398c86a1c104f0992bd788dd4bb065449be4;hpb=769848c03895b63e5662eb7e4ec8c4866f7d0183 diff --git a/mm/swap_state.c b/mm/swap_state.c index 67daecb..6d1daeb 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -10,12 +10,14 @@ #include #include #include +#include #include #include #include #include #include #include +#include #include @@ -32,13 +34,14 @@ static const struct address_space_operations swap_aops = { }; static struct backing_dev_info swap_backing_dev_info = { - .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, + .name = "swap", + .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, .unplug_io_fn = swap_unplug_io_fn, }; struct address_space swapper_space = { .page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN), - .tree_lock = __RW_LOCK_UNLOCKED(swapper_space.tree_lock), + .tree_lock = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock), .a_ops = &swap_aops, .i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear), .backing_dev_info = &swap_backing_dev_info, @@ -51,70 +54,69 @@ static struct { unsigned long del_total; unsigned long find_success; unsigned long find_total; - unsigned long noent_race; - unsigned long exist_race; } swap_cache_info; void show_swap_cache_info(void) { - printk("Swap cache: add %lu, delete %lu, find %lu/%lu, race %lu+%lu\n", + printk("%lu pages in swap cache\n", total_swapcache_pages); + printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n", swap_cache_info.add_total, swap_cache_info.del_total, - swap_cache_info.find_success, swap_cache_info.find_total, - swap_cache_info.noent_race, swap_cache_info.exist_race); - printk("Free swap = %lukB\n", nr_swap_pages << (PAGE_SHIFT - 10)); + swap_cache_info.find_success, swap_cache_info.find_total); + printk("Free swap = %ldkB\n", nr_swap_pages << (PAGE_SHIFT - 10)); printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10)); } /* - * __add_to_swap_cache resembles add_to_page_cache on swapper_space, + * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space, * but sets SwapCache flag and private instead of mapping and index. */ -static int __add_to_swap_cache(struct page *page, swp_entry_t entry, - gfp_t gfp_mask) +static int __add_to_swap_cache(struct page *page, swp_entry_t entry) { int error; - BUG_ON(PageSwapCache(page)); - BUG_ON(PagePrivate(page)); - error = radix_tree_preload(gfp_mask); - if (!error) { - write_lock_irq(&swapper_space.tree_lock); - error = radix_tree_insert(&swapper_space.page_tree, - entry.val, page); - if (!error) { - page_cache_get(page); - SetPageLocked(page); - SetPageSwapCache(page); - set_page_private(page, entry.val); - total_swapcache_pages++; - __inc_zone_page_state(page, NR_FILE_PAGES); - } - write_unlock_irq(&swapper_space.tree_lock); - radix_tree_preload_end(); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(PageSwapCache(page)); + VM_BUG_ON(!PageSwapBacked(page)); + + page_cache_get(page); + SetPageSwapCache(page); + set_page_private(page, entry.val); + + spin_lock_irq(&swapper_space.tree_lock); + error = radix_tree_insert(&swapper_space.page_tree, entry.val, page); + if (likely(!error)) { + total_swapcache_pages++; + __inc_zone_page_state(page, NR_FILE_PAGES); + INC_CACHE_INFO(add_total); + } + spin_unlock_irq(&swapper_space.tree_lock); + + if (unlikely(error)) { + /* + * Only the context which have set SWAP_HAS_CACHE flag + * would call add_to_swap_cache(). + * So add_to_swap_cache() doesn't returns -EEXIST. + */ + VM_BUG_ON(error == -EEXIST); + set_page_private(page, 0UL); + ClearPageSwapCache(page); + page_cache_release(page); } + return error; } -static int add_to_swap_cache(struct page *page, swp_entry_t entry) + +int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) { int error; - if (!swap_duplicate(entry)) { - INC_CACHE_INFO(noent_race); - return -ENOENT; - } - error = __add_to_swap_cache(page, entry, GFP_KERNEL); - /* - * Anon pages are already on the LRU, we don't run lru_cache_add here. - */ - if (error) { - swap_free(entry); - if (error == -EEXIST) - INC_CACHE_INFO(exist_race); - return error; + error = radix_tree_preload(gfp_mask); + if (!error) { + error = __add_to_swap_cache(page, entry); + radix_tree_preload_end(); } - INC_CACHE_INFO(add_total); - return 0; + return error; } /* @@ -123,10 +125,9 @@ static int add_to_swap_cache(struct page *page, swp_entry_t entry) */ void __delete_from_swap_cache(struct page *page) { - BUG_ON(!PageLocked(page)); - BUG_ON(!PageSwapCache(page)); - BUG_ON(PageWriteback(page)); - BUG_ON(PagePrivate(page)); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(!PageSwapCache(page)); + VM_BUG_ON(PageWriteback(page)); radix_tree_delete(&swapper_space.page_tree, page_private(page)); set_page_private(page, 0); @@ -143,48 +144,42 @@ void __delete_from_swap_cache(struct page *page) * Allocate swap space for the page and add the page to the * swap cache. Caller needs to hold the page lock. */ -int add_to_swap(struct page * page, gfp_t gfp_mask) +int add_to_swap(struct page *page) { swp_entry_t entry; int err; - BUG_ON(!PageLocked(page)); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(!PageUptodate(page)); - for (;;) { - entry = get_swap_page(); - if (!entry.val) - return 0; + entry = get_swap_page(); + if (!entry.val) + return 0; + /* + * Radix-tree node allocations from PF_MEMALLOC contexts could + * completely exhaust the page allocator. __GFP_NOMEMALLOC + * stops emergency reserves from being allocated. + * + * TODO: this could cause a theoretical memory reclaim + * deadlock in the swap out path. + */ + /* + * Add it to the swap cache and mark it dirty + */ + err = add_to_swap_cache(page, entry, + __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN); + + if (!err) { /* Success */ + SetPageDirty(page); + return 1; + } else { /* -ENOMEM radix-tree allocation failure */ /* - * Radix-tree node allocations from PF_MEMALLOC contexts could - * completely exhaust the page allocator. __GFP_NOMEMALLOC - * stops emergency reserves from being allocated. - * - * TODO: this could cause a theoretical memory reclaim - * deadlock in the swap out path. - */ - /* - * Add it to the swap cache and mark it dirty + * add_to_swap_cache() doesn't return -EEXIST, so we can safely + * clear SWAP_HAS_CACHE flag. */ - err = __add_to_swap_cache(page, entry, - gfp_mask|__GFP_NOMEMALLOC|__GFP_NOWARN); - - switch (err) { - case 0: /* Success */ - SetPageUptodate(page); - SetPageDirty(page); - INC_CACHE_INFO(add_total); - return 1; - case -EEXIST: - /* Raced with "speculative" read_swap_cache_async */ - INC_CACHE_INFO(exist_race); - swap_free(entry); - continue; - default: - /* -ENOMEM radix-tree allocation failure */ - swap_free(entry); - return 0; - } + swapcache_free(entry, NULL); + return 0; } } @@ -200,60 +195,26 @@ void delete_from_swap_cache(struct page *page) entry.val = page_private(page); - write_lock_irq(&swapper_space.tree_lock); + spin_lock_irq(&swapper_space.tree_lock); __delete_from_swap_cache(page); - write_unlock_irq(&swapper_space.tree_lock); + spin_unlock_irq(&swapper_space.tree_lock); - swap_free(entry); + swapcache_free(entry, page); page_cache_release(page); } -/* - * Strange swizzling function only for use by shmem_writepage - */ -int move_to_swap_cache(struct page *page, swp_entry_t entry) -{ - int err = __add_to_swap_cache(page, entry, GFP_ATOMIC); - if (!err) { - remove_from_page_cache(page); - page_cache_release(page); /* pagecache ref */ - if (!swap_duplicate(entry)) - BUG(); - SetPageDirty(page); - INC_CACHE_INFO(add_total); - } else if (err == -EEXIST) - INC_CACHE_INFO(exist_race); - return err; -} - -/* - * Strange swizzling function for shmem_getpage (and shmem_unuse) - */ -int move_from_swap_cache(struct page *page, unsigned long index, - struct address_space *mapping) -{ - int err = add_to_page_cache(page, mapping, index, GFP_ATOMIC); - if (!err) { - delete_from_swap_cache(page); - /* shift page from clean_pages to dirty_pages list */ - ClearPageDirty(page); - set_page_dirty(page); - } - return err; -} - /* * If we are the only user, then try to free up the swap cache. * * Its ok to check for PageSwapCache without the page lock - * here because we are going to recheck again inside - * exclusive_swap_page() _with_ the lock. + * here because we are going to recheck again inside + * try_to_free_swap() _with_ the lock. * - Marcelo */ static inline void free_swap_cache(struct page *page) { - if (PageSwapCache(page) && !TestSetPageLocked(page)) { - remove_exclusive_swap_page(page); + if (PageSwapCache(page) && !page_mapped(page) && trylock_page(page)) { + try_to_free_swap(page); unlock_page(page); } } @@ -314,7 +275,7 @@ struct page * lookup_swap_cache(swp_entry_t entry) * A failure return means that either the page allocation failed or that * the swap entry is no longer in use. */ -struct page *read_swap_cache_async(swp_entry_t entry, +struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, struct vm_area_struct *vma, unsigned long addr) { struct page *found_page, *new_page = NULL; @@ -334,34 +295,102 @@ struct page *read_swap_cache_async(swp_entry_t entry, * Get a new page to read into from swap. */ if (!new_page) { - new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, - vma, addr); + new_page = alloc_page_vma(gfp_mask, vma, addr); if (!new_page) break; /* Out of memory */ } /* - * Associate the page with swap entry in the swap cache. - * May fail (-ENOENT) if swap entry has been freed since - * our caller observed it. May fail (-EEXIST) if there - * is already a page associated with this entry in the - * swap cache: added by a racing read_swap_cache_async, - * or by try_to_swap_out (or shmem_writepage) re-using - * the just freed swap entry for an existing page. - * May fail (-ENOMEM) if radix-tree node allocation failed. + * call radix_tree_preload() while we can wait. + */ + err = radix_tree_preload(gfp_mask & GFP_KERNEL); + if (err) + break; + + /* + * Swap entry may have been freed since our caller observed it. */ - err = add_to_swap_cache(new_page, entry); - if (!err) { + err = swapcache_prepare(entry); + if (err == -EEXIST) { /* seems racy */ + radix_tree_preload_end(); + continue; + } + if (err) { /* swp entry is obsolete ? */ + radix_tree_preload_end(); + break; + } + + /* May fail (-ENOMEM) if radix-tree node allocation failed. */ + __set_page_locked(new_page); + SetPageSwapBacked(new_page); + err = __add_to_swap_cache(new_page, entry); + if (likely(!err)) { + radix_tree_preload_end(); /* * Initiate read into locked page and return. */ - lru_cache_add_active(new_page); - swap_readpage(NULL, new_page); + lru_cache_add_anon(new_page); + swap_readpage(new_page); return new_page; } - } while (err != -ENOENT && err != -ENOMEM); + radix_tree_preload_end(); + ClearPageSwapBacked(new_page); + __clear_page_locked(new_page); + /* + * add_to_swap_cache() doesn't return -EEXIST, so we can safely + * clear SWAP_HAS_CACHE flag. + */ + swapcache_free(entry, NULL); + } while (err != -ENOMEM); if (new_page) page_cache_release(new_page); return found_page; } + +/** + * swapin_readahead - swap in pages in hope we need them soon + * @entry: swap entry of this memory + * @gfp_mask: memory allocation flags + * @vma: user vma this address belongs to + * @addr: target address for mempolicy + * + * Returns the struct page for entry and addr, after queueing swapin. + * + * Primitive swap readahead code. We simply read an aligned block of + * (1 << page_cluster) entries in the swap area. This method is chosen + * because it doesn't cost us any seek time. We also make sure to queue + * the 'original' request together with the readahead ones... + * + * This has been extended to use the NUMA policies from the mm triggering + * the readahead. + * + * Caller must hold down_read on the vma->vm_mm if vma is not NULL. + */ +struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, + struct vm_area_struct *vma, unsigned long addr) +{ + int nr_pages; + struct page *page; + unsigned long offset; + unsigned long end_offset; + + /* + * Get starting offset for readaround, and number of pages to read. + * Adjust starting address by readbehind (for NUMA interleave case)? + * No, it's very unlikely that swap layout would follow vma layout, + * more likely that neighbouring swap pages came from the same node: + * so use the same "addr" to choose the same node for each swap read. + */ + nr_pages = valid_swaphandles(entry, &offset); + for (end_offset = offset + nr_pages; offset < end_offset; offset++) { + /* Ok, do the async read-ahead now */ + page = read_swap_cache_async(swp_entry(swp_type(entry), offset), + gfp_mask, vma, addr); + if (!page) + break; + page_cache_release(page); + } + lru_add_drain(); /* Push any new pages onto the LRU now */ + return read_swap_cache_async(entry, gfp_mask, vma, addr); +}