diff options
| -rw-r--r-- | include/linux/swap.h | 6 | ||||
| -rw-r--r-- | mm/shmem.c | 11 | ||||
| -rw-r--r-- | mm/swapfile.c | 47 |
3 files changed, 42 insertions, 22 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index 389e7bd92cca..ac43d87b89b0 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -157,6 +157,7 @@ enum { #define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */ #define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */ #define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */ +#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */ /* * The in-memory structure used to track swap areas. @@ -316,6 +317,7 @@ extern swp_entry_t get_swap_page(void); extern swp_entry_t get_swap_page_of_type(int); extern int valid_swaphandles(swp_entry_t, unsigned long *); extern int add_swap_count_continuation(swp_entry_t, gfp_t); +extern void swap_shmem_alloc(swp_entry_t); extern int swap_duplicate(swp_entry_t); extern int swapcache_prepare(swp_entry_t); extern void swap_free(swp_entry_t); @@ -394,6 +396,10 @@ static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask) return 0; } +static inline void swap_shmem_alloc(swp_entry_t swp) +{ +} + static inline int swap_duplicate(swp_entry_t swp) { return 0; diff --git a/mm/shmem.c b/mm/shmem.c index 356dd99566ec..4fb41c83daca 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1017,7 +1017,14 @@ int shmem_unuse(swp_entry_t entry, struct page *page) goto out; } mutex_unlock(&shmem_swaplist_mutex); -out: return found; /* 0 or 1 or -ENOMEM */ + /* + * Can some race bring us here? We've been holding page lock, + * so I think not; but would rather try again later than BUG() + */ + unlock_page(page); + page_cache_release(page); +out: + return (found < 0) ? found : 0; } /* @@ -1080,7 +1087,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) else inode = NULL; spin_unlock(&info->lock); - swap_duplicate(swap); + swap_shmem_alloc(swap); BUG_ON(page_mapped(page)); page_cache_release(page); /* pagecache ref */ swap_writepage(page, wbc); diff --git a/mm/swapfile.c b/mm/swapfile.c index cc5e7ebf2d2c..58bec6600167 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -548,6 +548,12 @@ static unsigned char swap_entry_free(struct swap_info_struct *p, if (usage == SWAP_HAS_CACHE) { VM_BUG_ON(!has_cache); has_cache = 0; + } else if (count == SWAP_MAP_SHMEM) { + /* + * Or we could insist on shmem.c using a special + * swap_shmem_free() and free_shmem_swap_and_cache()... + */ + count = 0; } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { if (count == COUNT_CONTINUED) { if (swap_count_continued(p, offset, count)) @@ -1031,7 +1037,6 @@ static int try_to_unuse(unsigned int type) swp_entry_t entry; unsigned int i = 0; int retval = 0; - int shmem; /* * When searching mms for an entry, a good strategy is to @@ -1107,17 +1112,18 @@ static int try_to_unuse(unsigned int type) /* * Remove all references to entry. - * Whenever we reach init_mm, there's no address space - * to search, but use it as a reminder to search shmem. */ - shmem = 0; swcount = *swap_map; - if (swap_count(swcount)) { - if (start_mm == &init_mm) - shmem = shmem_unuse(entry, page); - else - retval = unuse_mm(start_mm, entry, page); + if (swap_count(swcount) == SWAP_MAP_SHMEM) { + retval = shmem_unuse(entry, page); + /* page has already been unlocked and released */ + if (retval < 0) + break; + continue; } + if (swap_count(swcount) && start_mm != &init_mm) + retval = unuse_mm(start_mm, entry, page); + if (swap_count(*swap_map)) { int set_start_mm = (*swap_map >= swcount); struct list_head *p = &start_mm->mmlist; @@ -1128,7 +1134,7 @@ static int try_to_unuse(unsigned int type) atomic_inc(&new_start_mm->mm_users); atomic_inc(&prev_mm->mm_users); spin_lock(&mmlist_lock); - while (swap_count(*swap_map) && !retval && !shmem && + while (swap_count(*swap_map) && !retval && (p = p->next) != &start_mm->mmlist) { mm = list_entry(p, struct mm_struct, mmlist); if (!atomic_inc_not_zero(&mm->mm_users)) @@ -1142,10 +1148,9 @@ static int try_to_unuse(unsigned int type) swcount = *swap_map; if (!swap_count(swcount)) /* any usage ? */ ; - else if (mm == &init_mm) { + else if (mm == &init_mm) set_start_mm = 1; - shmem = shmem_unuse(entry, page); - } else + else retval = unuse_mm(mm, entry, page); if (set_start_mm && *swap_map < swcount) { @@ -1161,13 +1166,6 @@ static int try_to_unuse(unsigned int type) mmput(start_mm); start_mm = new_start_mm; } - if (shmem) { - /* page has already been unlocked and released */ - if (shmem > 0) - continue; - retval = shmem; - break; - } if (retval) { unlock_page(page); page_cache_release(page); @@ -2127,6 +2125,15 @@ bad_file: } /* + * Help swapoff by noting that swap entry belongs to shmem/tmpfs + * (in which case its reference count is never incremented). + */ +void swap_shmem_alloc(swp_entry_t entry) +{ + __swap_duplicate(entry, SWAP_MAP_SHMEM); +} + +/* * increase reference count of swap entry by 1. */ int swap_duplicate(swp_entry_t entry) |