diff options
| -rw-r--r-- | include/linux/swapops.h | 23 | ||||
| -rw-r--r-- | mm/filemap.c | 49 | ||||
| -rw-r--r-- | mm/swapfile.c | 20 |
3 files changed, 66 insertions, 26 deletions
diff --git a/include/linux/swapops.h b/include/linux/swapops.h index cd42e30b7c6..2189d3ffc85 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -1,3 +1,8 @@ +#ifndef _LINUX_SWAPOPS_H +#define _LINUX_SWAPOPS_H + +#include <linux/radix-tree.h> + /* * swapcache pages are stored in the swapper_space radix tree. We want to * get good packing density in that tree, so the index should be dense in @@ -76,6 +81,22 @@ static inline pte_t swp_entry_to_pte(swp_entry_t entry) return __swp_entry_to_pte(arch_entry); } +static inline swp_entry_t radix_to_swp_entry(void *arg) +{ + swp_entry_t entry; + + entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT; + return entry; +} + +static inline void *swp_to_radix_entry(swp_entry_t entry) +{ + unsigned long value; + + value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT; + return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY); +} + #ifdef CONFIG_MIGRATION static inline swp_entry_t make_migration_entry(struct page *page, int write) { @@ -169,3 +190,5 @@ static inline int non_swap_entry(swp_entry_t entry) return 0; } #endif + +#endif /* _LINUX_SWAPOPS_H */ diff --git a/mm/filemap.c b/mm/filemap.c index b83aebfd0a0..76bfb6460f5 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -714,9 +714,12 @@ repeat: page = radix_tree_deref_slot(pagep); if (unlikely(!page)) goto out; - if (radix_tree_deref_retry(page)) + if (radix_tree_exception(page)) { + if (radix_tree_exceptional_entry(page)) + goto out; + /* radix_tree_deref_retry(page) */ goto repeat; - + } if (!page_cache_get_speculative(page)) goto repeat; @@ -753,7 +756,7 @@ struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) repeat: page = find_get_page(mapping, offset); - if (page) { + if (page && !radix_tree_exception(page)) { lock_page(page); /* Has the page been truncated? */ if (unlikely(page->mapping != mapping)) { @@ -849,11 +852,14 @@ repeat: if (unlikely(!page)) continue; - /* - * This can only trigger when the entry at index 0 moves out - * of or back to the root: none yet gotten, safe to restart. - */ - if (radix_tree_deref_retry(page)) { + if (radix_tree_exception(page)) { + if (radix_tree_exceptional_entry(page)) + continue; + /* + * radix_tree_deref_retry(page): + * can only trigger when entry at index 0 moves out of + * or back to root: none yet gotten, safe to restart. + */ WARN_ON(start | i); goto restart; } @@ -912,12 +918,16 @@ repeat: if (unlikely(!page)) continue; - /* - * This can only trigger when the entry at index 0 moves out - * of or back to the root: none yet gotten, safe to restart. - */ - if (radix_tree_deref_retry(page)) + if (radix_tree_exception(page)) { + if (radix_tree_exceptional_entry(page)) + break; + /* + * radix_tree_deref_retry(page): + * can only trigger when entry at index 0 moves out of + * or back to root: none yet gotten, safe to restart. + */ goto restart; + } if (!page_cache_get_speculative(page)) goto repeat; @@ -977,12 +987,15 @@ repeat: if (unlikely(!page)) continue; - /* - * This can only trigger when the entry at index 0 moves out - * of or back to the root: none yet gotten, safe to restart. - */ - if (radix_tree_deref_retry(page)) + if (radix_tree_exception(page)) { + BUG_ON(radix_tree_exceptional_entry(page)); + /* + * radix_tree_deref_retry(page): + * can only trigger when entry at index 0 moves out of + * or back to root: none yet gotten, safe to restart. + */ goto restart; + } if (!page_cache_get_speculative(page)) goto repeat; diff --git a/mm/swapfile.c b/mm/swapfile.c index 1b8c3390724..17bc224bce6 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1924,20 +1924,24 @@ static unsigned long read_swap_header(struct swap_info_struct *p, /* * Find out how many pages are allowed for a single swap - * device. There are two limiting factors: 1) the number of - * bits for the swap offset in the swp_entry_t type and - * 2) the number of bits in the a swap pte as defined by - * the different architectures. In order to find the - * largest possible bit mask a swap entry with swap type 0 + * device. There are three limiting factors: 1) the number + * of bits for the swap offset in the swp_entry_t type, and + * 2) the number of bits in the swap pte as defined by the + * the different architectures, and 3) the number of free bits + * in an exceptional radix_tree entry. In order to find the + * largest possible bit mask, a swap entry with swap type 0 * and swap offset ~0UL is created, encoded to a swap pte, - * decoded to a swp_entry_t again and finally the swap + * decoded to a swp_entry_t again, and finally the swap * offset is extracted. This will mask all the bits from * the initial ~0UL mask that can't be encoded in either * the swp_entry_t or the architecture definition of a - * swap pte. + * swap pte. Then the same is done for a radix_tree entry. */ maxpages = swp_offset(pte_to_swp_entry( - swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; + swp_entry_to_pte(swp_entry(0, ~0UL)))); + maxpages = swp_offset(radix_to_swp_entry( + swp_to_radix_entry(swp_entry(0, maxpages)))) + 1; + if (maxpages > swap_header->info.last_page) { maxpages = swap_header->info.last_page + 1; /* p->max is an unsigned int: don't overflow it */ |