--- zzzz-none-000/linux-3.10.107/mm/swap_state.c 2017-06-27 09:49:32.000000000 +0000 +++ scorpion-7490-727/linux-3.10.107/mm/swap_state.c 2021-02-04 17:41:59.000000000 +0000 @@ -17,7 +17,6 @@ #include #include #include -#include #include @@ -28,19 +27,16 @@ static const struct address_space_operations swap_aops = { .writepage = swap_writepage, .set_page_dirty = swap_set_page_dirty, +#ifdef CONFIG_MIGRATION .migratepage = migrate_page, -}; - -static struct backing_dev_info swap_backing_dev_info = { - .name = "swap", - .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, +#endif }; struct address_space swapper_spaces[MAX_SWAPFILES] = { [0 ... MAX_SWAPFILES - 1] = { .page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN), + .i_mmap_writable = ATOMIC_INIT(0), .a_ops = &swap_aops, - .backing_dev_info = &swap_backing_dev_info, } }; @@ -63,6 +59,8 @@ return ret; } +static atomic_t swapin_readahead_hits = ATOMIC_INIT(4); + void show_swap_cache_info(void) { printk("%lu pages in swap cache\n", total_swapcache_pages()); @@ -83,9 +81,9 @@ int error; struct address_space *address_space; - VM_BUG_ON(!PageLocked(page)); - VM_BUG_ON(PageSwapCache(page)); - VM_BUG_ON(!PageSwapBacked(page)); + VM_BUG_ON_PAGE(!PageLocked(page), page); + VM_BUG_ON_PAGE(PageSwapCache(page), page); + VM_BUG_ON_PAGE(!PageSwapBacked(page), page); page_cache_get(page); SetPageSwapCache(page); @@ -122,7 +120,7 @@ { int error; - error = radix_tree_preload(gfp_mask); + error = radix_tree_maybe_preload(gfp_mask); if (!error) { error = __add_to_swap_cache(page, entry); radix_tree_preload_end(); @@ -139,9 +137,9 @@ swp_entry_t entry; struct address_space *address_space; - VM_BUG_ON(!PageLocked(page)); - VM_BUG_ON(!PageSwapCache(page)); - VM_BUG_ON(PageWriteback(page)); + VM_BUG_ON_PAGE(!PageLocked(page), page); + VM_BUG_ON_PAGE(!PageSwapCache(page), page); + VM_BUG_ON_PAGE(PageWriteback(page), page); entry.val = page_private(page); address_space = swap_address_space(entry); @@ -165,8 +163,8 @@ swp_entry_t entry; int err; - VM_BUG_ON(!PageLocked(page)); - VM_BUG_ON(!PageUptodate(page)); + VM_BUG_ON_PAGE(!PageLocked(page), page); + VM_BUG_ON_PAGE(!PageUptodate(page), page); entry = get_swap_page(); if (!entry.val) @@ -174,7 +172,7 @@ if (unlikely(PageTransHuge(page))) if (unlikely(split_huge_page_to_list(page, list))) { - swapcache_free(entry, NULL); + swapcache_free(entry); return 0; } @@ -200,7 +198,7 @@ * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - swapcache_free(entry, NULL); + swapcache_free(entry); return 0; } } @@ -223,7 +221,7 @@ __delete_from_swap_cache(page); spin_unlock_irq(&address_space->tree_lock); - swapcache_free(entry, page); + swapcache_free(entry); page_cache_release(page); } @@ -260,18 +258,12 @@ void free_pages_and_swap_cache(struct page **pages, int nr) { struct page **pagep = pages; + int i; lru_add_drain(); - while (nr) { - int todo = min(nr, PAGEVEC_SIZE); - int i; - - for (i = 0; i < todo; i++) - free_swap_cache(pagep[i]); - release_pages(pagep, todo, 0); - pagep += todo; - nr -= todo; - } + for (i = 0; i < nr; i++) + free_swap_cache(pagep[i]); + release_pages(pagep, nr, false); } /* @@ -286,24 +278,24 @@ page = find_get_page(swap_address_space(entry), entry.val); - if (page) + if (page) { INC_CACHE_INFO(find_success); + if (TestClearPageReadahead(page)) + atomic_inc(&swapin_readahead_hits); + } INC_CACHE_INFO(find_total); return page; } -/* - * Locate a page of swap in physical memory, reserving swap cache space - * and reading the disk if it is not already cached. - * 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, gfp_t gfp_mask, - struct vm_area_struct *vma, unsigned long addr) +struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, + struct vm_area_struct *vma, unsigned long addr, + bool *new_page_allocated) { struct page *found_page, *new_page = NULL; + struct address_space *swapper_space = swap_address_space(entry); int err; + *new_page_allocated = false; do { /* @@ -311,8 +303,7 @@ * called after lookup_swap_cache() failed, re-calling * that would confuse statistics. */ - found_page = find_get_page(swap_address_space(entry), - entry.val); + found_page = find_get_page(swapper_space, entry.val); if (found_page) break; @@ -328,7 +319,7 @@ /* * call radix_tree_preload() while we can wait. */ - err = radix_tree_preload(gfp_mask & GFP_KERNEL); + err = radix_tree_maybe_preload(gfp_mask & GFP_KERNEL); if (err) break; @@ -371,7 +362,7 @@ * Initiate read into locked page and return. */ lru_cache_add_anon(new_page); - swap_readpage(new_page); + *new_page_allocated = true; return new_page; } radix_tree_preload_end(); @@ -381,7 +372,7 @@ * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - swapcache_free(entry, NULL); + swapcache_free(entry); } while (err != -ENOMEM); if (new_page) @@ -389,6 +380,69 @@ return found_page; } +/* + * Locate a page of swap in physical memory, reserving swap cache space + * and reading the disk if it is not already cached. + * 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, gfp_t gfp_mask, + struct vm_area_struct *vma, unsigned long addr) +{ + bool page_was_allocated; + struct page *retpage = __read_swap_cache_async(entry, gfp_mask, + vma, addr, &page_was_allocated); + + if (page_was_allocated) + swap_readpage(retpage); + + return retpage; +} + +static unsigned long swapin_nr_pages(unsigned long offset) +{ + static unsigned long prev_offset; + unsigned int pages, max_pages, last_ra; + static atomic_t last_readahead_pages; + + max_pages = 1 << READ_ONCE(page_cluster); + if (max_pages <= 1) + return 1; + + /* + * This heuristic has been found to work well on both sequential and + * random loads, swapping to hard disk or to SSD: please don't ask + * what the "+ 2" means, it just happens to work well, that's all. + */ + pages = atomic_xchg(&swapin_readahead_hits, 0) + 2; + if (pages == 2) { + /* + * We can have no readahead hits to judge by: but must not get + * stuck here forever, so check for an adjacent offset instead + * (and don't even bother to check whether swap type is same). + */ + if (offset != prev_offset + 1 && offset != prev_offset - 1) + pages = 1; + prev_offset = offset; + } else { + unsigned int roundup = 4; + while (roundup < pages) + roundup <<= 1; + pages = roundup; + } + + if (pages > max_pages) + pages = max_pages; + + /* Don't shrink readahead too fast */ + last_ra = atomic_read(&last_readahead_pages) / 2; + if (pages < last_ra) + pages = last_ra; + atomic_set(&last_readahead_pages, pages); + + return pages; +} + /** * swapin_readahead - swap in pages in hope we need them soon * @entry: swap entry of this memory @@ -412,11 +466,16 @@ struct vm_area_struct *vma, unsigned long addr) { struct page *page; - unsigned long offset = swp_offset(entry); + unsigned long entry_offset = swp_offset(entry); + unsigned long offset = entry_offset; unsigned long start_offset, end_offset; - unsigned long mask = (1UL << page_cluster) - 1; + unsigned long mask; struct blk_plug plug; + mask = swapin_nr_pages(offset) - 1; + if (!mask) + goto skip; + /* Read a page_cluster sized and aligned cluster around offset. */ start_offset = offset & ~mask; end_offset = offset | mask; @@ -430,10 +489,13 @@ gfp_mask, vma, addr); if (!page) continue; + if (offset != entry_offset) + SetPageReadahead(page); page_cache_release(page); } blk_finish_plug(&plug); lru_add_drain(); /* Push any new pages onto the LRU now */ +skip: return read_swap_cache_async(entry, gfp_mask, vma, addr); }