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![David Rientjes](/assets/img/avatar_default.png)
Free frontswap_map if an error is encountered before enable_swap_info(). Signed-off-by: David Rientjes <rientjes@google.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> [4.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
3716 lines
94 KiB
C
3716 lines
94 KiB
C
/*
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* linux/mm/swapfile.c
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*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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* Swap reorganised 29.12.95, Stephen Tweedie
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*/
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#include <linux/mm.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/task.h>
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#include <linux/hugetlb.h>
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#include <linux/mman.h>
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#include <linux/slab.h>
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#include <linux/kernel_stat.h>
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#include <linux/swap.h>
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#include <linux/vmalloc.h>
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#include <linux/pagemap.h>
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#include <linux/namei.h>
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#include <linux/shmem_fs.h>
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#include <linux/blkdev.h>
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#include <linux/random.h>
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#include <linux/writeback.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/init.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/security.h>
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#include <linux/backing-dev.h>
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#include <linux/mutex.h>
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#include <linux/capability.h>
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#include <linux/syscalls.h>
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#include <linux/memcontrol.h>
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#include <linux/poll.h>
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#include <linux/oom.h>
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#include <linux/frontswap.h>
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#include <linux/swapfile.h>
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#include <linux/export.h>
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#include <linux/swap_slots.h>
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#include <linux/sort.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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#include <linux/swapops.h>
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#include <linux/swap_cgroup.h>
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static bool swap_count_continued(struct swap_info_struct *, pgoff_t,
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unsigned char);
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static void free_swap_count_continuations(struct swap_info_struct *);
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static sector_t map_swap_entry(swp_entry_t, struct block_device**);
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DEFINE_SPINLOCK(swap_lock);
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static unsigned int nr_swapfiles;
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atomic_long_t nr_swap_pages;
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/*
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* Some modules use swappable objects and may try to swap them out under
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* memory pressure (via the shrinker). Before doing so, they may wish to
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* check to see if any swap space is available.
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*/
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EXPORT_SYMBOL_GPL(nr_swap_pages);
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/* protected with swap_lock. reading in vm_swap_full() doesn't need lock */
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long total_swap_pages;
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static int least_priority = -1;
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static const char Bad_file[] = "Bad swap file entry ";
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static const char Unused_file[] = "Unused swap file entry ";
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static const char Bad_offset[] = "Bad swap offset entry ";
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static const char Unused_offset[] = "Unused swap offset entry ";
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/*
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* all active swap_info_structs
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* protected with swap_lock, and ordered by priority.
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*/
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PLIST_HEAD(swap_active_head);
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/*
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* all available (active, not full) swap_info_structs
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* protected with swap_avail_lock, ordered by priority.
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* This is used by get_swap_page() instead of swap_active_head
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* because swap_active_head includes all swap_info_structs,
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* but get_swap_page() doesn't need to look at full ones.
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* This uses its own lock instead of swap_lock because when a
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* swap_info_struct changes between not-full/full, it needs to
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* add/remove itself to/from this list, but the swap_info_struct->lock
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* is held and the locking order requires swap_lock to be taken
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* before any swap_info_struct->lock.
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*/
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struct plist_head *swap_avail_heads;
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static DEFINE_SPINLOCK(swap_avail_lock);
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struct swap_info_struct *swap_info[MAX_SWAPFILES];
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static DEFINE_MUTEX(swapon_mutex);
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static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait);
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/* Activity counter to indicate that a swapon or swapoff has occurred */
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static atomic_t proc_poll_event = ATOMIC_INIT(0);
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atomic_t nr_rotate_swap = ATOMIC_INIT(0);
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static inline unsigned char swap_count(unsigned char ent)
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{
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return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */
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}
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/* returns 1 if swap entry is freed */
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static int
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__try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset)
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{
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swp_entry_t entry = swp_entry(si->type, offset);
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struct page *page;
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int ret = 0;
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page = find_get_page(swap_address_space(entry), swp_offset(entry));
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if (!page)
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return 0;
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/*
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* This function is called from scan_swap_map() and it's called
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* by vmscan.c at reclaiming pages. So, we hold a lock on a page, here.
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* We have to use trylock for avoiding deadlock. This is a special
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* case and you should use try_to_free_swap() with explicit lock_page()
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* in usual operations.
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*/
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if (trylock_page(page)) {
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ret = try_to_free_swap(page);
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unlock_page(page);
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}
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put_page(page);
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return ret;
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}
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/*
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* swapon tell device that all the old swap contents can be discarded,
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* to allow the swap device to optimize its wear-levelling.
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*/
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static int discard_swap(struct swap_info_struct *si)
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{
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struct swap_extent *se;
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sector_t start_block;
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sector_t nr_blocks;
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int err = 0;
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/* Do not discard the swap header page! */
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se = &si->first_swap_extent;
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start_block = (se->start_block + 1) << (PAGE_SHIFT - 9);
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nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);
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if (nr_blocks) {
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err = blkdev_issue_discard(si->bdev, start_block,
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nr_blocks, GFP_KERNEL, 0);
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if (err)
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return err;
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cond_resched();
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}
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list_for_each_entry(se, &si->first_swap_extent.list, list) {
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start_block = se->start_block << (PAGE_SHIFT - 9);
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nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);
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err = blkdev_issue_discard(si->bdev, start_block,
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nr_blocks, GFP_KERNEL, 0);
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if (err)
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break;
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cond_resched();
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}
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return err; /* That will often be -EOPNOTSUPP */
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}
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/*
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* swap allocation tell device that a cluster of swap can now be discarded,
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* to allow the swap device to optimize its wear-levelling.
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*/
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static void discard_swap_cluster(struct swap_info_struct *si,
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pgoff_t start_page, pgoff_t nr_pages)
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{
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struct swap_extent *se = si->curr_swap_extent;
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int found_extent = 0;
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while (nr_pages) {
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if (se->start_page <= start_page &&
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start_page < se->start_page + se->nr_pages) {
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pgoff_t offset = start_page - se->start_page;
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sector_t start_block = se->start_block + offset;
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sector_t nr_blocks = se->nr_pages - offset;
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if (nr_blocks > nr_pages)
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nr_blocks = nr_pages;
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start_page += nr_blocks;
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nr_pages -= nr_blocks;
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if (!found_extent++)
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si->curr_swap_extent = se;
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start_block <<= PAGE_SHIFT - 9;
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nr_blocks <<= PAGE_SHIFT - 9;
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if (blkdev_issue_discard(si->bdev, start_block,
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nr_blocks, GFP_NOIO, 0))
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break;
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}
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se = list_next_entry(se, list);
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}
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}
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#ifdef CONFIG_THP_SWAP
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#define SWAPFILE_CLUSTER HPAGE_PMD_NR
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#else
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#define SWAPFILE_CLUSTER 256
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#endif
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#define LATENCY_LIMIT 256
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static inline void cluster_set_flag(struct swap_cluster_info *info,
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unsigned int flag)
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{
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info->flags = flag;
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}
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static inline unsigned int cluster_count(struct swap_cluster_info *info)
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{
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return info->data;
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}
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static inline void cluster_set_count(struct swap_cluster_info *info,
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unsigned int c)
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{
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info->data = c;
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}
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static inline void cluster_set_count_flag(struct swap_cluster_info *info,
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unsigned int c, unsigned int f)
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{
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info->flags = f;
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info->data = c;
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}
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static inline unsigned int cluster_next(struct swap_cluster_info *info)
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{
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return info->data;
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}
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static inline void cluster_set_next(struct swap_cluster_info *info,
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unsigned int n)
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{
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info->data = n;
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}
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static inline void cluster_set_next_flag(struct swap_cluster_info *info,
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unsigned int n, unsigned int f)
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{
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info->flags = f;
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info->data = n;
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}
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static inline bool cluster_is_free(struct swap_cluster_info *info)
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{
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return info->flags & CLUSTER_FLAG_FREE;
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}
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static inline bool cluster_is_null(struct swap_cluster_info *info)
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{
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return info->flags & CLUSTER_FLAG_NEXT_NULL;
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}
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static inline void cluster_set_null(struct swap_cluster_info *info)
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{
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info->flags = CLUSTER_FLAG_NEXT_NULL;
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info->data = 0;
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}
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static inline bool cluster_is_huge(struct swap_cluster_info *info)
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{
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return info->flags & CLUSTER_FLAG_HUGE;
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}
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static inline void cluster_clear_huge(struct swap_cluster_info *info)
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{
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info->flags &= ~CLUSTER_FLAG_HUGE;
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}
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static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si,
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unsigned long offset)
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{
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struct swap_cluster_info *ci;
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ci = si->cluster_info;
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if (ci) {
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ci += offset / SWAPFILE_CLUSTER;
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spin_lock(&ci->lock);
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}
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return ci;
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}
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static inline void unlock_cluster(struct swap_cluster_info *ci)
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{
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if (ci)
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spin_unlock(&ci->lock);
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}
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static inline struct swap_cluster_info *lock_cluster_or_swap_info(
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struct swap_info_struct *si,
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unsigned long offset)
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{
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struct swap_cluster_info *ci;
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ci = lock_cluster(si, offset);
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if (!ci)
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spin_lock(&si->lock);
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return ci;
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}
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static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si,
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struct swap_cluster_info *ci)
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{
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if (ci)
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unlock_cluster(ci);
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else
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spin_unlock(&si->lock);
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}
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static inline bool cluster_list_empty(struct swap_cluster_list *list)
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{
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return cluster_is_null(&list->head);
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}
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static inline unsigned int cluster_list_first(struct swap_cluster_list *list)
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{
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return cluster_next(&list->head);
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}
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static void cluster_list_init(struct swap_cluster_list *list)
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{
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cluster_set_null(&list->head);
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cluster_set_null(&list->tail);
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}
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static void cluster_list_add_tail(struct swap_cluster_list *list,
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struct swap_cluster_info *ci,
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unsigned int idx)
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{
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if (cluster_list_empty(list)) {
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cluster_set_next_flag(&list->head, idx, 0);
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cluster_set_next_flag(&list->tail, idx, 0);
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} else {
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struct swap_cluster_info *ci_tail;
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unsigned int tail = cluster_next(&list->tail);
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/*
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* Nested cluster lock, but both cluster locks are
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* only acquired when we held swap_info_struct->lock
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*/
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ci_tail = ci + tail;
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spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING);
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cluster_set_next(ci_tail, idx);
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spin_unlock(&ci_tail->lock);
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cluster_set_next_flag(&list->tail, idx, 0);
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}
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}
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static unsigned int cluster_list_del_first(struct swap_cluster_list *list,
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struct swap_cluster_info *ci)
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{
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unsigned int idx;
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idx = cluster_next(&list->head);
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if (cluster_next(&list->tail) == idx) {
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cluster_set_null(&list->head);
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cluster_set_null(&list->tail);
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} else
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cluster_set_next_flag(&list->head,
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cluster_next(&ci[idx]), 0);
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return idx;
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}
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/* Add a cluster to discard list and schedule it to do discard */
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static void swap_cluster_schedule_discard(struct swap_info_struct *si,
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unsigned int idx)
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{
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/*
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* If scan_swap_map() can't find a free cluster, it will check
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* si->swap_map directly. To make sure the discarding cluster isn't
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* taken by scan_swap_map(), mark the swap entries bad (occupied). It
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* will be cleared after discard
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*/
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memset(si->swap_map + idx * SWAPFILE_CLUSTER,
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SWAP_MAP_BAD, SWAPFILE_CLUSTER);
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cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx);
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schedule_work(&si->discard_work);
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}
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static void __free_cluster(struct swap_info_struct *si, unsigned long idx)
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{
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struct swap_cluster_info *ci = si->cluster_info;
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cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE);
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cluster_list_add_tail(&si->free_clusters, ci, idx);
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}
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/*
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* Doing discard actually. After a cluster discard is finished, the cluster
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* will be added to free cluster list. caller should hold si->lock.
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*/
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static void swap_do_scheduled_discard(struct swap_info_struct *si)
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{
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struct swap_cluster_info *info, *ci;
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unsigned int idx;
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info = si->cluster_info;
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while (!cluster_list_empty(&si->discard_clusters)) {
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idx = cluster_list_del_first(&si->discard_clusters, info);
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spin_unlock(&si->lock);
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discard_swap_cluster(si, idx * SWAPFILE_CLUSTER,
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SWAPFILE_CLUSTER);
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spin_lock(&si->lock);
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ci = lock_cluster(si, idx * SWAPFILE_CLUSTER);
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__free_cluster(si, idx);
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memset(si->swap_map + idx * SWAPFILE_CLUSTER,
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0, SWAPFILE_CLUSTER);
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unlock_cluster(ci);
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}
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}
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static void swap_discard_work(struct work_struct *work)
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{
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struct swap_info_struct *si;
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si = container_of(work, struct swap_info_struct, discard_work);
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spin_lock(&si->lock);
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swap_do_scheduled_discard(si);
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spin_unlock(&si->lock);
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}
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static void alloc_cluster(struct swap_info_struct *si, unsigned long idx)
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{
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struct swap_cluster_info *ci = si->cluster_info;
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VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx);
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cluster_list_del_first(&si->free_clusters, ci);
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cluster_set_count_flag(ci + idx, 0, 0);
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}
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static void free_cluster(struct swap_info_struct *si, unsigned long idx)
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{
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struct swap_cluster_info *ci = si->cluster_info + idx;
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VM_BUG_ON(cluster_count(ci) != 0);
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/*
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* If the swap is discardable, prepare discard the cluster
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* instead of free it immediately. The cluster will be freed
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* after discard.
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*/
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if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) ==
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(SWP_WRITEOK | SWP_PAGE_DISCARD)) {
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swap_cluster_schedule_discard(si, idx);
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return;
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}
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__free_cluster(si, idx);
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}
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/*
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* The cluster corresponding to page_nr will be used. The cluster will be
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* removed from free cluster list and its usage counter will be increased.
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*/
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static void inc_cluster_info_page(struct swap_info_struct *p,
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struct swap_cluster_info *cluster_info, unsigned long page_nr)
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{
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unsigned long idx = page_nr / SWAPFILE_CLUSTER;
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|
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if (!cluster_info)
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return;
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if (cluster_is_free(&cluster_info[idx]))
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alloc_cluster(p, idx);
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VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER);
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cluster_set_count(&cluster_info[idx],
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cluster_count(&cluster_info[idx]) + 1);
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}
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|
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/*
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* The cluster corresponding to page_nr decreases one usage. If the usage
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* counter becomes 0, which means no page in the cluster is in using, we can
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* optionally discard the cluster and add it to free cluster list.
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*/
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static void dec_cluster_info_page(struct swap_info_struct *p,
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struct swap_cluster_info *cluster_info, unsigned long page_nr)
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{
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unsigned long idx = page_nr / SWAPFILE_CLUSTER;
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if (!cluster_info)
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return;
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VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0);
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cluster_set_count(&cluster_info[idx],
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cluster_count(&cluster_info[idx]) - 1);
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if (cluster_count(&cluster_info[idx]) == 0)
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free_cluster(p, idx);
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|
}
|
|
|
|
/*
|
|
* It's possible scan_swap_map() uses a free cluster in the middle of free
|
|
* cluster list. Avoiding such abuse to avoid list corruption.
|
|
*/
|
|
static bool
|
|
scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si,
|
|
unsigned long offset)
|
|
{
|
|
struct percpu_cluster *percpu_cluster;
|
|
bool conflict;
|
|
|
|
offset /= SWAPFILE_CLUSTER;
|
|
conflict = !cluster_list_empty(&si->free_clusters) &&
|
|
offset != cluster_list_first(&si->free_clusters) &&
|
|
cluster_is_free(&si->cluster_info[offset]);
|
|
|
|
if (!conflict)
|
|
return false;
|
|
|
|
percpu_cluster = this_cpu_ptr(si->percpu_cluster);
|
|
cluster_set_null(&percpu_cluster->index);
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Try to get a swap entry from current cpu's swap entry pool (a cluster). This
|
|
* might involve allocating a new cluster for current CPU too.
|
|
*/
|
|
static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si,
|
|
unsigned long *offset, unsigned long *scan_base)
|
|
{
|
|
struct percpu_cluster *cluster;
|
|
struct swap_cluster_info *ci;
|
|
bool found_free;
|
|
unsigned long tmp, max;
|
|
|
|
new_cluster:
|
|
cluster = this_cpu_ptr(si->percpu_cluster);
|
|
if (cluster_is_null(&cluster->index)) {
|
|
if (!cluster_list_empty(&si->free_clusters)) {
|
|
cluster->index = si->free_clusters.head;
|
|
cluster->next = cluster_next(&cluster->index) *
|
|
SWAPFILE_CLUSTER;
|
|
} else if (!cluster_list_empty(&si->discard_clusters)) {
|
|
/*
|
|
* we don't have free cluster but have some clusters in
|
|
* discarding, do discard now and reclaim them
|
|
*/
|
|
swap_do_scheduled_discard(si);
|
|
*scan_base = *offset = si->cluster_next;
|
|
goto new_cluster;
|
|
} else
|
|
return false;
|
|
}
|
|
|
|
found_free = false;
|
|
|
|
/*
|
|
* Other CPUs can use our cluster if they can't find a free cluster,
|
|
* check if there is still free entry in the cluster
|
|
*/
|
|
tmp = cluster->next;
|
|
max = min_t(unsigned long, si->max,
|
|
(cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER);
|
|
if (tmp >= max) {
|
|
cluster_set_null(&cluster->index);
|
|
goto new_cluster;
|
|
}
|
|
ci = lock_cluster(si, tmp);
|
|
while (tmp < max) {
|
|
if (!si->swap_map[tmp]) {
|
|
found_free = true;
|
|
break;
|
|
}
|
|
tmp++;
|
|
}
|
|
unlock_cluster(ci);
|
|
if (!found_free) {
|
|
cluster_set_null(&cluster->index);
|
|
goto new_cluster;
|
|
}
|
|
cluster->next = tmp + 1;
|
|
*offset = tmp;
|
|
*scan_base = tmp;
|
|
return found_free;
|
|
}
|
|
|
|
static void __del_from_avail_list(struct swap_info_struct *p)
|
|
{
|
|
int nid;
|
|
|
|
for_each_node(nid)
|
|
plist_del(&p->avail_lists[nid], &swap_avail_heads[nid]);
|
|
}
|
|
|
|
static void del_from_avail_list(struct swap_info_struct *p)
|
|
{
|
|
spin_lock(&swap_avail_lock);
|
|
__del_from_avail_list(p);
|
|
spin_unlock(&swap_avail_lock);
|
|
}
|
|
|
|
static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset,
|
|
unsigned int nr_entries)
|
|
{
|
|
unsigned int end = offset + nr_entries - 1;
|
|
|
|
if (offset == si->lowest_bit)
|
|
si->lowest_bit += nr_entries;
|
|
if (end == si->highest_bit)
|
|
si->highest_bit -= nr_entries;
|
|
si->inuse_pages += nr_entries;
|
|
if (si->inuse_pages == si->pages) {
|
|
si->lowest_bit = si->max;
|
|
si->highest_bit = 0;
|
|
del_from_avail_list(si);
|
|
}
|
|
}
|
|
|
|
static void add_to_avail_list(struct swap_info_struct *p)
|
|
{
|
|
int nid;
|
|
|
|
spin_lock(&swap_avail_lock);
|
|
for_each_node(nid) {
|
|
WARN_ON(!plist_node_empty(&p->avail_lists[nid]));
|
|
plist_add(&p->avail_lists[nid], &swap_avail_heads[nid]);
|
|
}
|
|
spin_unlock(&swap_avail_lock);
|
|
}
|
|
|
|
static void swap_range_free(struct swap_info_struct *si, unsigned long offset,
|
|
unsigned int nr_entries)
|
|
{
|
|
unsigned long end = offset + nr_entries - 1;
|
|
void (*swap_slot_free_notify)(struct block_device *, unsigned long);
|
|
|
|
if (offset < si->lowest_bit)
|
|
si->lowest_bit = offset;
|
|
if (end > si->highest_bit) {
|
|
bool was_full = !si->highest_bit;
|
|
|
|
si->highest_bit = end;
|
|
if (was_full && (si->flags & SWP_WRITEOK))
|
|
add_to_avail_list(si);
|
|
}
|
|
atomic_long_add(nr_entries, &nr_swap_pages);
|
|
si->inuse_pages -= nr_entries;
|
|
if (si->flags & SWP_BLKDEV)
|
|
swap_slot_free_notify =
|
|
si->bdev->bd_disk->fops->swap_slot_free_notify;
|
|
else
|
|
swap_slot_free_notify = NULL;
|
|
while (offset <= end) {
|
|
frontswap_invalidate_page(si->type, offset);
|
|
if (swap_slot_free_notify)
|
|
swap_slot_free_notify(si->bdev, offset);
|
|
offset++;
|
|
}
|
|
}
|
|
|
|
static int scan_swap_map_slots(struct swap_info_struct *si,
|
|
unsigned char usage, int nr,
|
|
swp_entry_t slots[])
|
|
{
|
|
struct swap_cluster_info *ci;
|
|
unsigned long offset;
|
|
unsigned long scan_base;
|
|
unsigned long last_in_cluster = 0;
|
|
int latency_ration = LATENCY_LIMIT;
|
|
int n_ret = 0;
|
|
|
|
if (nr > SWAP_BATCH)
|
|
nr = SWAP_BATCH;
|
|
|
|
/*
|
|
* We try to cluster swap pages by allocating them sequentially
|
|
* in swap. Once we've allocated SWAPFILE_CLUSTER pages this
|
|
* way, however, we resort to first-free allocation, starting
|
|
* a new cluster. This prevents us from scattering swap pages
|
|
* all over the entire swap partition, so that we reduce
|
|
* overall disk seek times between swap pages. -- sct
|
|
* But we do now try to find an empty cluster. -Andrea
|
|
* And we let swap pages go all over an SSD partition. Hugh
|
|
*/
|
|
|
|
si->flags += SWP_SCANNING;
|
|
scan_base = offset = si->cluster_next;
|
|
|
|
/* SSD algorithm */
|
|
if (si->cluster_info) {
|
|
if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base))
|
|
goto checks;
|
|
else
|
|
goto scan;
|
|
}
|
|
|
|
if (unlikely(!si->cluster_nr--)) {
|
|
if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) {
|
|
si->cluster_nr = SWAPFILE_CLUSTER - 1;
|
|
goto checks;
|
|
}
|
|
|
|
spin_unlock(&si->lock);
|
|
|
|
/*
|
|
* If seek is expensive, start searching for new cluster from
|
|
* start of partition, to minimize the span of allocated swap.
|
|
* If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info
|
|
* case, just handled by scan_swap_map_try_ssd_cluster() above.
|
|
*/
|
|
scan_base = offset = si->lowest_bit;
|
|
last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
|
|
|
|
/* Locate the first empty (unaligned) cluster */
|
|
for (; last_in_cluster <= si->highest_bit; offset++) {
|
|
if (si->swap_map[offset])
|
|
last_in_cluster = offset + SWAPFILE_CLUSTER;
|
|
else if (offset == last_in_cluster) {
|
|
spin_lock(&si->lock);
|
|
offset -= SWAPFILE_CLUSTER - 1;
|
|
si->cluster_next = offset;
|
|
si->cluster_nr = SWAPFILE_CLUSTER - 1;
|
|
goto checks;
|
|
}
|
|
if (unlikely(--latency_ration < 0)) {
|
|
cond_resched();
|
|
latency_ration = LATENCY_LIMIT;
|
|
}
|
|
}
|
|
|
|
offset = scan_base;
|
|
spin_lock(&si->lock);
|
|
si->cluster_nr = SWAPFILE_CLUSTER - 1;
|
|
}
|
|
|
|
checks:
|
|
if (si->cluster_info) {
|
|
while (scan_swap_map_ssd_cluster_conflict(si, offset)) {
|
|
/* take a break if we already got some slots */
|
|
if (n_ret)
|
|
goto done;
|
|
if (!scan_swap_map_try_ssd_cluster(si, &offset,
|
|
&scan_base))
|
|
goto scan;
|
|
}
|
|
}
|
|
if (!(si->flags & SWP_WRITEOK))
|
|
goto no_page;
|
|
if (!si->highest_bit)
|
|
goto no_page;
|
|
if (offset > si->highest_bit)
|
|
scan_base = offset = si->lowest_bit;
|
|
|
|
ci = lock_cluster(si, offset);
|
|
/* reuse swap entry of cache-only swap if not busy. */
|
|
if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
|
|
int swap_was_freed;
|
|
unlock_cluster(ci);
|
|
spin_unlock(&si->lock);
|
|
swap_was_freed = __try_to_reclaim_swap(si, offset);
|
|
spin_lock(&si->lock);
|
|
/* entry was freed successfully, try to use this again */
|
|
if (swap_was_freed)
|
|
goto checks;
|
|
goto scan; /* check next one */
|
|
}
|
|
|
|
if (si->swap_map[offset]) {
|
|
unlock_cluster(ci);
|
|
if (!n_ret)
|
|
goto scan;
|
|
else
|
|
goto done;
|
|
}
|
|
si->swap_map[offset] = usage;
|
|
inc_cluster_info_page(si, si->cluster_info, offset);
|
|
unlock_cluster(ci);
|
|
|
|
swap_range_alloc(si, offset, 1);
|
|
si->cluster_next = offset + 1;
|
|
slots[n_ret++] = swp_entry(si->type, offset);
|
|
|
|
/* got enough slots or reach max slots? */
|
|
if ((n_ret == nr) || (offset >= si->highest_bit))
|
|
goto done;
|
|
|
|
/* search for next available slot */
|
|
|
|
/* time to take a break? */
|
|
if (unlikely(--latency_ration < 0)) {
|
|
if (n_ret)
|
|
goto done;
|
|
spin_unlock(&si->lock);
|
|
cond_resched();
|
|
spin_lock(&si->lock);
|
|
latency_ration = LATENCY_LIMIT;
|
|
}
|
|
|
|
/* try to get more slots in cluster */
|
|
if (si->cluster_info) {
|
|
if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base))
|
|
goto checks;
|
|
else
|
|
goto done;
|
|
}
|
|
/* non-ssd case */
|
|
++offset;
|
|
|
|
/* non-ssd case, still more slots in cluster? */
|
|
if (si->cluster_nr && !si->swap_map[offset]) {
|
|
--si->cluster_nr;
|
|
goto checks;
|
|
}
|
|
|
|
done:
|
|
si->flags -= SWP_SCANNING;
|
|
return n_ret;
|
|
|
|
scan:
|
|
spin_unlock(&si->lock);
|
|
while (++offset <= si->highest_bit) {
|
|
if (!si->swap_map[offset]) {
|
|
spin_lock(&si->lock);
|
|
goto checks;
|
|
}
|
|
if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
|
|
spin_lock(&si->lock);
|
|
goto checks;
|
|
}
|
|
if (unlikely(--latency_ration < 0)) {
|
|
cond_resched();
|
|
latency_ration = LATENCY_LIMIT;
|
|
}
|
|
}
|
|
offset = si->lowest_bit;
|
|
while (offset < scan_base) {
|
|
if (!si->swap_map[offset]) {
|
|
spin_lock(&si->lock);
|
|
goto checks;
|
|
}
|
|
if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
|
|
spin_lock(&si->lock);
|
|
goto checks;
|
|
}
|
|
if (unlikely(--latency_ration < 0)) {
|
|
cond_resched();
|
|
latency_ration = LATENCY_LIMIT;
|
|
}
|
|
offset++;
|
|
}
|
|
spin_lock(&si->lock);
|
|
|
|
no_page:
|
|
si->flags -= SWP_SCANNING;
|
|
return n_ret;
|
|
}
|
|
|
|
#ifdef CONFIG_THP_SWAP
|
|
static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot)
|
|
{
|
|
unsigned long idx;
|
|
struct swap_cluster_info *ci;
|
|
unsigned long offset, i;
|
|
unsigned char *map;
|
|
|
|
if (cluster_list_empty(&si->free_clusters))
|
|
return 0;
|
|
|
|
idx = cluster_list_first(&si->free_clusters);
|
|
offset = idx * SWAPFILE_CLUSTER;
|
|
ci = lock_cluster(si, offset);
|
|
alloc_cluster(si, idx);
|
|
cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE);
|
|
|
|
map = si->swap_map + offset;
|
|
for (i = 0; i < SWAPFILE_CLUSTER; i++)
|
|
map[i] = SWAP_HAS_CACHE;
|
|
unlock_cluster(ci);
|
|
swap_range_alloc(si, offset, SWAPFILE_CLUSTER);
|
|
*slot = swp_entry(si->type, offset);
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx)
|
|
{
|
|
unsigned long offset = idx * SWAPFILE_CLUSTER;
|
|
struct swap_cluster_info *ci;
|
|
|
|
ci = lock_cluster(si, offset);
|
|
cluster_set_count_flag(ci, 0, 0);
|
|
free_cluster(si, idx);
|
|
unlock_cluster(ci);
|
|
swap_range_free(si, offset, SWAPFILE_CLUSTER);
|
|
}
|
|
#else
|
|
static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot)
|
|
{
|
|
VM_WARN_ON_ONCE(1);
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_THP_SWAP */
|
|
|
|
static unsigned long scan_swap_map(struct swap_info_struct *si,
|
|
unsigned char usage)
|
|
{
|
|
swp_entry_t entry;
|
|
int n_ret;
|
|
|
|
n_ret = scan_swap_map_slots(si, usage, 1, &entry);
|
|
|
|
if (n_ret)
|
|
return swp_offset(entry);
|
|
else
|
|
return 0;
|
|
|
|
}
|
|
|
|
int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[])
|
|
{
|
|
unsigned long nr_pages = cluster ? SWAPFILE_CLUSTER : 1;
|
|
struct swap_info_struct *si, *next;
|
|
long avail_pgs;
|
|
int n_ret = 0;
|
|
int node;
|
|
|
|
/* Only single cluster request supported */
|
|
WARN_ON_ONCE(n_goal > 1 && cluster);
|
|
|
|
avail_pgs = atomic_long_read(&nr_swap_pages) / nr_pages;
|
|
if (avail_pgs <= 0)
|
|
goto noswap;
|
|
|
|
if (n_goal > SWAP_BATCH)
|
|
n_goal = SWAP_BATCH;
|
|
|
|
if (n_goal > avail_pgs)
|
|
n_goal = avail_pgs;
|
|
|
|
atomic_long_sub(n_goal * nr_pages, &nr_swap_pages);
|
|
|
|
spin_lock(&swap_avail_lock);
|
|
|
|
start_over:
|
|
node = numa_node_id();
|
|
plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) {
|
|
/* requeue si to after same-priority siblings */
|
|
plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]);
|
|
spin_unlock(&swap_avail_lock);
|
|
spin_lock(&si->lock);
|
|
if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) {
|
|
spin_lock(&swap_avail_lock);
|
|
if (plist_node_empty(&si->avail_lists[node])) {
|
|
spin_unlock(&si->lock);
|
|
goto nextsi;
|
|
}
|
|
WARN(!si->highest_bit,
|
|
"swap_info %d in list but !highest_bit\n",
|
|
si->type);
|
|
WARN(!(si->flags & SWP_WRITEOK),
|
|
"swap_info %d in list but !SWP_WRITEOK\n",
|
|
si->type);
|
|
__del_from_avail_list(si);
|
|
spin_unlock(&si->lock);
|
|
goto nextsi;
|
|
}
|
|
if (cluster) {
|
|
if (!(si->flags & SWP_FILE))
|
|
n_ret = swap_alloc_cluster(si, swp_entries);
|
|
} else
|
|
n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE,
|
|
n_goal, swp_entries);
|
|
spin_unlock(&si->lock);
|
|
if (n_ret || cluster)
|
|
goto check_out;
|
|
pr_debug("scan_swap_map of si %d failed to find offset\n",
|
|
si->type);
|
|
|
|
spin_lock(&swap_avail_lock);
|
|
nextsi:
|
|
/*
|
|
* if we got here, it's likely that si was almost full before,
|
|
* and since scan_swap_map() can drop the si->lock, multiple
|
|
* callers probably all tried to get a page from the same si
|
|
* and it filled up before we could get one; or, the si filled
|
|
* up between us dropping swap_avail_lock and taking si->lock.
|
|
* Since we dropped the swap_avail_lock, the swap_avail_head
|
|
* list may have been modified; so if next is still in the
|
|
* swap_avail_head list then try it, otherwise start over
|
|
* if we have not gotten any slots.
|
|
*/
|
|
if (plist_node_empty(&next->avail_lists[node]))
|
|
goto start_over;
|
|
}
|
|
|
|
spin_unlock(&swap_avail_lock);
|
|
|
|
check_out:
|
|
if (n_ret < n_goal)
|
|
atomic_long_add((long)(n_goal - n_ret) * nr_pages,
|
|
&nr_swap_pages);
|
|
noswap:
|
|
return n_ret;
|
|
}
|
|
|
|
/* The only caller of this function is now suspend routine */
|
|
swp_entry_t get_swap_page_of_type(int type)
|
|
{
|
|
struct swap_info_struct *si;
|
|
pgoff_t offset;
|
|
|
|
si = swap_info[type];
|
|
spin_lock(&si->lock);
|
|
if (si && (si->flags & SWP_WRITEOK)) {
|
|
atomic_long_dec(&nr_swap_pages);
|
|
/* This is called for allocating swap entry, not cache */
|
|
offset = scan_swap_map(si, 1);
|
|
if (offset) {
|
|
spin_unlock(&si->lock);
|
|
return swp_entry(type, offset);
|
|
}
|
|
atomic_long_inc(&nr_swap_pages);
|
|
}
|
|
spin_unlock(&si->lock);
|
|
return (swp_entry_t) {0};
|
|
}
|
|
|
|
static struct swap_info_struct *__swap_info_get(swp_entry_t entry)
|
|
{
|
|
struct swap_info_struct *p;
|
|
unsigned long offset, type;
|
|
|
|
if (!entry.val)
|
|
goto out;
|
|
type = swp_type(entry);
|
|
if (type >= nr_swapfiles)
|
|
goto bad_nofile;
|
|
p = swap_info[type];
|
|
if (!(p->flags & SWP_USED))
|
|
goto bad_device;
|
|
offset = swp_offset(entry);
|
|
if (offset >= p->max)
|
|
goto bad_offset;
|
|
return p;
|
|
|
|
bad_offset:
|
|
pr_err("swap_info_get: %s%08lx\n", Bad_offset, entry.val);
|
|
goto out;
|
|
bad_device:
|
|
pr_err("swap_info_get: %s%08lx\n", Unused_file, entry.val);
|
|
goto out;
|
|
bad_nofile:
|
|
pr_err("swap_info_get: %s%08lx\n", Bad_file, entry.val);
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
static struct swap_info_struct *_swap_info_get(swp_entry_t entry)
|
|
{
|
|
struct swap_info_struct *p;
|
|
|
|
p = __swap_info_get(entry);
|
|
if (!p)
|
|
goto out;
|
|
if (!p->swap_map[swp_offset(entry)])
|
|
goto bad_free;
|
|
return p;
|
|
|
|
bad_free:
|
|
pr_err("swap_info_get: %s%08lx\n", Unused_offset, entry.val);
|
|
goto out;
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
static struct swap_info_struct *swap_info_get(swp_entry_t entry)
|
|
{
|
|
struct swap_info_struct *p;
|
|
|
|
p = _swap_info_get(entry);
|
|
if (p)
|
|
spin_lock(&p->lock);
|
|
return p;
|
|
}
|
|
|
|
static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry,
|
|
struct swap_info_struct *q)
|
|
{
|
|
struct swap_info_struct *p;
|
|
|
|
p = _swap_info_get(entry);
|
|
|
|
if (p != q) {
|
|
if (q != NULL)
|
|
spin_unlock(&q->lock);
|
|
if (p != NULL)
|
|
spin_lock(&p->lock);
|
|
}
|
|
return p;
|
|
}
|
|
|
|
static unsigned char __swap_entry_free(struct swap_info_struct *p,
|
|
swp_entry_t entry, unsigned char usage)
|
|
{
|
|
struct swap_cluster_info *ci;
|
|
unsigned long offset = swp_offset(entry);
|
|
unsigned char count;
|
|
unsigned char has_cache;
|
|
|
|
ci = lock_cluster_or_swap_info(p, offset);
|
|
|
|
count = p->swap_map[offset];
|
|
|
|
has_cache = count & SWAP_HAS_CACHE;
|
|
count &= ~SWAP_HAS_CACHE;
|
|
|
|
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))
|
|
count = SWAP_MAP_MAX | COUNT_CONTINUED;
|
|
else
|
|
count = SWAP_MAP_MAX;
|
|
} else
|
|
count--;
|
|
}
|
|
|
|
usage = count | has_cache;
|
|
p->swap_map[offset] = usage ? : SWAP_HAS_CACHE;
|
|
|
|
unlock_cluster_or_swap_info(p, ci);
|
|
|
|
return usage;
|
|
}
|
|
|
|
static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry)
|
|
{
|
|
struct swap_cluster_info *ci;
|
|
unsigned long offset = swp_offset(entry);
|
|
unsigned char count;
|
|
|
|
ci = lock_cluster(p, offset);
|
|
count = p->swap_map[offset];
|
|
VM_BUG_ON(count != SWAP_HAS_CACHE);
|
|
p->swap_map[offset] = 0;
|
|
dec_cluster_info_page(p, p->cluster_info, offset);
|
|
unlock_cluster(ci);
|
|
|
|
mem_cgroup_uncharge_swap(entry, 1);
|
|
swap_range_free(p, offset, 1);
|
|
}
|
|
|
|
/*
|
|
* Caller has made sure that the swap device corresponding to entry
|
|
* is still around or has not been recycled.
|
|
*/
|
|
void swap_free(swp_entry_t entry)
|
|
{
|
|
struct swap_info_struct *p;
|
|
|
|
p = _swap_info_get(entry);
|
|
if (p) {
|
|
if (!__swap_entry_free(p, entry, 1))
|
|
free_swap_slot(entry);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Called after dropping swapcache to decrease refcnt to swap entries.
|
|
*/
|
|
static void swapcache_free(swp_entry_t entry)
|
|
{
|
|
struct swap_info_struct *p;
|
|
|
|
p = _swap_info_get(entry);
|
|
if (p) {
|
|
if (!__swap_entry_free(p, entry, SWAP_HAS_CACHE))
|
|
free_swap_slot(entry);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_THP_SWAP
|
|
static void swapcache_free_cluster(swp_entry_t entry)
|
|
{
|
|
unsigned long offset = swp_offset(entry);
|
|
unsigned long idx = offset / SWAPFILE_CLUSTER;
|
|
struct swap_cluster_info *ci;
|
|
struct swap_info_struct *si;
|
|
unsigned char *map;
|
|
unsigned int i, free_entries = 0;
|
|
unsigned char val;
|
|
|
|
si = _swap_info_get(entry);
|
|
if (!si)
|
|
return;
|
|
|
|
ci = lock_cluster(si, offset);
|
|
VM_BUG_ON(!cluster_is_huge(ci));
|
|
map = si->swap_map + offset;
|
|
for (i = 0; i < SWAPFILE_CLUSTER; i++) {
|
|
val = map[i];
|
|
VM_BUG_ON(!(val & SWAP_HAS_CACHE));
|
|
if (val == SWAP_HAS_CACHE)
|
|
free_entries++;
|
|
}
|
|
if (!free_entries) {
|
|
for (i = 0; i < SWAPFILE_CLUSTER; i++)
|
|
map[i] &= ~SWAP_HAS_CACHE;
|
|
}
|
|
cluster_clear_huge(ci);
|
|
unlock_cluster(ci);
|
|
if (free_entries == SWAPFILE_CLUSTER) {
|
|
spin_lock(&si->lock);
|
|
ci = lock_cluster(si, offset);
|
|
memset(map, 0, SWAPFILE_CLUSTER);
|
|
unlock_cluster(ci);
|
|
mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER);
|
|
swap_free_cluster(si, idx);
|
|
spin_unlock(&si->lock);
|
|
} else if (free_entries) {
|
|
for (i = 0; i < SWAPFILE_CLUSTER; i++, entry.val++) {
|
|
if (!__swap_entry_free(si, entry, SWAP_HAS_CACHE))
|
|
free_swap_slot(entry);
|
|
}
|
|
}
|
|
}
|
|
|
|
int split_swap_cluster(swp_entry_t entry)
|
|
{
|
|
struct swap_info_struct *si;
|
|
struct swap_cluster_info *ci;
|
|
unsigned long offset = swp_offset(entry);
|
|
|
|
si = _swap_info_get(entry);
|
|
if (!si)
|
|
return -EBUSY;
|
|
ci = lock_cluster(si, offset);
|
|
cluster_clear_huge(ci);
|
|
unlock_cluster(ci);
|
|
return 0;
|
|
}
|
|
#else
|
|
static inline void swapcache_free_cluster(swp_entry_t entry)
|
|
{
|
|
}
|
|
#endif /* CONFIG_THP_SWAP */
|
|
|
|
void put_swap_page(struct page *page, swp_entry_t entry)
|
|
{
|
|
if (!PageTransHuge(page))
|
|
swapcache_free(entry);
|
|
else
|
|
swapcache_free_cluster(entry);
|
|
}
|
|
|
|
static int swp_entry_cmp(const void *ent1, const void *ent2)
|
|
{
|
|
const swp_entry_t *e1 = ent1, *e2 = ent2;
|
|
|
|
return (int)swp_type(*e1) - (int)swp_type(*e2);
|
|
}
|
|
|
|
void swapcache_free_entries(swp_entry_t *entries, int n)
|
|
{
|
|
struct swap_info_struct *p, *prev;
|
|
int i;
|
|
|
|
if (n <= 0)
|
|
return;
|
|
|
|
prev = NULL;
|
|
p = NULL;
|
|
|
|
/*
|
|
* Sort swap entries by swap device, so each lock is only taken once.
|
|
* nr_swapfiles isn't absolutely correct, but the overhead of sort() is
|
|
* so low that it isn't necessary to optimize further.
|
|
*/
|
|
if (nr_swapfiles > 1)
|
|
sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL);
|
|
for (i = 0; i < n; ++i) {
|
|
p = swap_info_get_cont(entries[i], prev);
|
|
if (p)
|
|
swap_entry_free(p, entries[i]);
|
|
prev = p;
|
|
}
|
|
if (p)
|
|
spin_unlock(&p->lock);
|
|
}
|
|
|
|
/*
|
|
* How many references to page are currently swapped out?
|
|
* This does not give an exact answer when swap count is continued,
|
|
* but does include the high COUNT_CONTINUED flag to allow for that.
|
|
*/
|
|
int page_swapcount(struct page *page)
|
|
{
|
|
int count = 0;
|
|
struct swap_info_struct *p;
|
|
struct swap_cluster_info *ci;
|
|
swp_entry_t entry;
|
|
unsigned long offset;
|
|
|
|
entry.val = page_private(page);
|
|
p = _swap_info_get(entry);
|
|
if (p) {
|
|
offset = swp_offset(entry);
|
|
ci = lock_cluster_or_swap_info(p, offset);
|
|
count = swap_count(p->swap_map[offset]);
|
|
unlock_cluster_or_swap_info(p, ci);
|
|
}
|
|
return count;
|
|
}
|
|
|
|
static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
|
|
{
|
|
int count = 0;
|
|
pgoff_t offset = swp_offset(entry);
|
|
struct swap_cluster_info *ci;
|
|
|
|
ci = lock_cluster_or_swap_info(si, offset);
|
|
count = swap_count(si->swap_map[offset]);
|
|
unlock_cluster_or_swap_info(si, ci);
|
|
return count;
|
|
}
|
|
|
|
/*
|
|
* How many references to @entry are currently swapped out?
|
|
* This does not give an exact answer when swap count is continued,
|
|
* but does include the high COUNT_CONTINUED flag to allow for that.
|
|
*/
|
|
int __swp_swapcount(swp_entry_t entry)
|
|
{
|
|
int count = 0;
|
|
struct swap_info_struct *si;
|
|
|
|
si = __swap_info_get(entry);
|
|
if (si)
|
|
count = swap_swapcount(si, entry);
|
|
return count;
|
|
}
|
|
|
|
/*
|
|
* How many references to @entry are currently swapped out?
|
|
* This considers COUNT_CONTINUED so it returns exact answer.
|
|
*/
|
|
int swp_swapcount(swp_entry_t entry)
|
|
{
|
|
int count, tmp_count, n;
|
|
struct swap_info_struct *p;
|
|
struct swap_cluster_info *ci;
|
|
struct page *page;
|
|
pgoff_t offset;
|
|
unsigned char *map;
|
|
|
|
p = _swap_info_get(entry);
|
|
if (!p)
|
|
return 0;
|
|
|
|
offset = swp_offset(entry);
|
|
|
|
ci = lock_cluster_or_swap_info(p, offset);
|
|
|
|
count = swap_count(p->swap_map[offset]);
|
|
if (!(count & COUNT_CONTINUED))
|
|
goto out;
|
|
|
|
count &= ~COUNT_CONTINUED;
|
|
n = SWAP_MAP_MAX + 1;
|
|
|
|
page = vmalloc_to_page(p->swap_map + offset);
|
|
offset &= ~PAGE_MASK;
|
|
VM_BUG_ON(page_private(page) != SWP_CONTINUED);
|
|
|
|
do {
|
|
page = list_next_entry(page, lru);
|
|
map = kmap_atomic(page);
|
|
tmp_count = map[offset];
|
|
kunmap_atomic(map);
|
|
|
|
count += (tmp_count & ~COUNT_CONTINUED) * n;
|
|
n *= (SWAP_CONT_MAX + 1);
|
|
} while (tmp_count & COUNT_CONTINUED);
|
|
out:
|
|
unlock_cluster_or_swap_info(p, ci);
|
|
return count;
|
|
}
|
|
|
|
#ifdef CONFIG_THP_SWAP
|
|
static bool swap_page_trans_huge_swapped(struct swap_info_struct *si,
|
|
swp_entry_t entry)
|
|
{
|
|
struct swap_cluster_info *ci;
|
|
unsigned char *map = si->swap_map;
|
|
unsigned long roffset = swp_offset(entry);
|
|
unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER);
|
|
int i;
|
|
bool ret = false;
|
|
|
|
ci = lock_cluster_or_swap_info(si, offset);
|
|
if (!ci || !cluster_is_huge(ci)) {
|
|
if (map[roffset] != SWAP_HAS_CACHE)
|
|
ret = true;
|
|
goto unlock_out;
|
|
}
|
|
for (i = 0; i < SWAPFILE_CLUSTER; i++) {
|
|
if (map[offset + i] != SWAP_HAS_CACHE) {
|
|
ret = true;
|
|
break;
|
|
}
|
|
}
|
|
unlock_out:
|
|
unlock_cluster_or_swap_info(si, ci);
|
|
return ret;
|
|
}
|
|
|
|
static bool page_swapped(struct page *page)
|
|
{
|
|
swp_entry_t entry;
|
|
struct swap_info_struct *si;
|
|
|
|
if (likely(!PageTransCompound(page)))
|
|
return page_swapcount(page) != 0;
|
|
|
|
page = compound_head(page);
|
|
entry.val = page_private(page);
|
|
si = _swap_info_get(entry);
|
|
if (si)
|
|
return swap_page_trans_huge_swapped(si, entry);
|
|
return false;
|
|
}
|
|
|
|
static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount,
|
|
int *total_swapcount)
|
|
{
|
|
int i, map_swapcount, _total_mapcount, _total_swapcount;
|
|
unsigned long offset = 0;
|
|
struct swap_info_struct *si;
|
|
struct swap_cluster_info *ci = NULL;
|
|
unsigned char *map = NULL;
|
|
int mapcount, swapcount = 0;
|
|
|
|
/* hugetlbfs shouldn't call it */
|
|
VM_BUG_ON_PAGE(PageHuge(page), page);
|
|
|
|
if (likely(!PageTransCompound(page))) {
|
|
mapcount = atomic_read(&page->_mapcount) + 1;
|
|
if (total_mapcount)
|
|
*total_mapcount = mapcount;
|
|
if (PageSwapCache(page))
|
|
swapcount = page_swapcount(page);
|
|
if (total_swapcount)
|
|
*total_swapcount = swapcount;
|
|
return mapcount + swapcount;
|
|
}
|
|
|
|
page = compound_head(page);
|
|
|
|
_total_mapcount = _total_swapcount = map_swapcount = 0;
|
|
if (PageSwapCache(page)) {
|
|
swp_entry_t entry;
|
|
|
|
entry.val = page_private(page);
|
|
si = _swap_info_get(entry);
|
|
if (si) {
|
|
map = si->swap_map;
|
|
offset = swp_offset(entry);
|
|
}
|
|
}
|
|
if (map)
|
|
ci = lock_cluster(si, offset);
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
mapcount = atomic_read(&page[i]._mapcount) + 1;
|
|
_total_mapcount += mapcount;
|
|
if (map) {
|
|
swapcount = swap_count(map[offset + i]);
|
|
_total_swapcount += swapcount;
|
|
}
|
|
map_swapcount = max(map_swapcount, mapcount + swapcount);
|
|
}
|
|
unlock_cluster(ci);
|
|
if (PageDoubleMap(page)) {
|
|
map_swapcount -= 1;
|
|
_total_mapcount -= HPAGE_PMD_NR;
|
|
}
|
|
mapcount = compound_mapcount(page);
|
|
map_swapcount += mapcount;
|
|
_total_mapcount += mapcount;
|
|
if (total_mapcount)
|
|
*total_mapcount = _total_mapcount;
|
|
if (total_swapcount)
|
|
*total_swapcount = _total_swapcount;
|
|
|
|
return map_swapcount;
|
|
}
|
|
#else
|
|
#define swap_page_trans_huge_swapped(si, entry) swap_swapcount(si, entry)
|
|
#define page_swapped(page) (page_swapcount(page) != 0)
|
|
|
|
static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount,
|
|
int *total_swapcount)
|
|
{
|
|
int mapcount, swapcount = 0;
|
|
|
|
/* hugetlbfs shouldn't call it */
|
|
VM_BUG_ON_PAGE(PageHuge(page), page);
|
|
|
|
mapcount = page_trans_huge_mapcount(page, total_mapcount);
|
|
if (PageSwapCache(page))
|
|
swapcount = page_swapcount(page);
|
|
if (total_swapcount)
|
|
*total_swapcount = swapcount;
|
|
return mapcount + swapcount;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* We can write to an anon page without COW if there are no other references
|
|
* to it. And as a side-effect, free up its swap: because the old content
|
|
* on disk will never be read, and seeking back there to write new content
|
|
* later would only waste time away from clustering.
|
|
*
|
|
* NOTE: total_map_swapcount should not be relied upon by the caller if
|
|
* reuse_swap_page() returns false, but it may be always overwritten
|
|
* (see the other implementation for CONFIG_SWAP=n).
|
|
*/
|
|
bool reuse_swap_page(struct page *page, int *total_map_swapcount)
|
|
{
|
|
int count, total_mapcount, total_swapcount;
|
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
if (unlikely(PageKsm(page)))
|
|
return false;
|
|
count = page_trans_huge_map_swapcount(page, &total_mapcount,
|
|
&total_swapcount);
|
|
if (total_map_swapcount)
|
|
*total_map_swapcount = total_mapcount + total_swapcount;
|
|
if (count == 1 && PageSwapCache(page) &&
|
|
(likely(!PageTransCompound(page)) ||
|
|
/* The remaining swap count will be freed soon */
|
|
total_swapcount == page_swapcount(page))) {
|
|
if (!PageWriteback(page)) {
|
|
page = compound_head(page);
|
|
delete_from_swap_cache(page);
|
|
SetPageDirty(page);
|
|
} else {
|
|
swp_entry_t entry;
|
|
struct swap_info_struct *p;
|
|
|
|
entry.val = page_private(page);
|
|
p = swap_info_get(entry);
|
|
if (p->flags & SWP_STABLE_WRITES) {
|
|
spin_unlock(&p->lock);
|
|
return false;
|
|
}
|
|
spin_unlock(&p->lock);
|
|
}
|
|
}
|
|
|
|
return count <= 1;
|
|
}
|
|
|
|
/*
|
|
* If swap is getting full, or if there are no more mappings of this page,
|
|
* then try_to_free_swap is called to free its swap space.
|
|
*/
|
|
int try_to_free_swap(struct page *page)
|
|
{
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
|
|
if (!PageSwapCache(page))
|
|
return 0;
|
|
if (PageWriteback(page))
|
|
return 0;
|
|
if (page_swapped(page))
|
|
return 0;
|
|
|
|
/*
|
|
* Once hibernation has begun to create its image of memory,
|
|
* there's a danger that one of the calls to try_to_free_swap()
|
|
* - most probably a call from __try_to_reclaim_swap() while
|
|
* hibernation is allocating its own swap pages for the image,
|
|
* but conceivably even a call from memory reclaim - will free
|
|
* the swap from a page which has already been recorded in the
|
|
* image as a clean swapcache page, and then reuse its swap for
|
|
* another page of the image. On waking from hibernation, the
|
|
* original page might be freed under memory pressure, then
|
|
* later read back in from swap, now with the wrong data.
|
|
*
|
|
* Hibernation suspends storage while it is writing the image
|
|
* to disk so check that here.
|
|
*/
|
|
if (pm_suspended_storage())
|
|
return 0;
|
|
|
|
page = compound_head(page);
|
|
delete_from_swap_cache(page);
|
|
SetPageDirty(page);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Free the swap entry like above, but also try to
|
|
* free the page cache entry if it is the last user.
|
|
*/
|
|
int free_swap_and_cache(swp_entry_t entry)
|
|
{
|
|
struct swap_info_struct *p;
|
|
struct page *page = NULL;
|
|
unsigned char count;
|
|
|
|
if (non_swap_entry(entry))
|
|
return 1;
|
|
|
|
p = _swap_info_get(entry);
|
|
if (p) {
|
|
count = __swap_entry_free(p, entry, 1);
|
|
if (count == SWAP_HAS_CACHE &&
|
|
!swap_page_trans_huge_swapped(p, entry)) {
|
|
page = find_get_page(swap_address_space(entry),
|
|
swp_offset(entry));
|
|
if (page && !trylock_page(page)) {
|
|
put_page(page);
|
|
page = NULL;
|
|
}
|
|
} else if (!count)
|
|
free_swap_slot(entry);
|
|
}
|
|
if (page) {
|
|
/*
|
|
* Not mapped elsewhere, or swap space full? Free it!
|
|
* Also recheck PageSwapCache now page is locked (above).
|
|
*/
|
|
if (PageSwapCache(page) && !PageWriteback(page) &&
|
|
(!page_mapped(page) || mem_cgroup_swap_full(page)) &&
|
|
!swap_page_trans_huge_swapped(p, entry)) {
|
|
page = compound_head(page);
|
|
delete_from_swap_cache(page);
|
|
SetPageDirty(page);
|
|
}
|
|
unlock_page(page);
|
|
put_page(page);
|
|
}
|
|
return p != NULL;
|
|
}
|
|
|
|
#ifdef CONFIG_HIBERNATION
|
|
/*
|
|
* Find the swap type that corresponds to given device (if any).
|
|
*
|
|
* @offset - number of the PAGE_SIZE-sized block of the device, starting
|
|
* from 0, in which the swap header is expected to be located.
|
|
*
|
|
* This is needed for the suspend to disk (aka swsusp).
|
|
*/
|
|
int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
|
|
{
|
|
struct block_device *bdev = NULL;
|
|
int type;
|
|
|
|
if (device)
|
|
bdev = bdget(device);
|
|
|
|
spin_lock(&swap_lock);
|
|
for (type = 0; type < nr_swapfiles; type++) {
|
|
struct swap_info_struct *sis = swap_info[type];
|
|
|
|
if (!(sis->flags & SWP_WRITEOK))
|
|
continue;
|
|
|
|
if (!bdev) {
|
|
if (bdev_p)
|
|
*bdev_p = bdgrab(sis->bdev);
|
|
|
|
spin_unlock(&swap_lock);
|
|
return type;
|
|
}
|
|
if (bdev == sis->bdev) {
|
|
struct swap_extent *se = &sis->first_swap_extent;
|
|
|
|
if (se->start_block == offset) {
|
|
if (bdev_p)
|
|
*bdev_p = bdgrab(sis->bdev);
|
|
|
|
spin_unlock(&swap_lock);
|
|
bdput(bdev);
|
|
return type;
|
|
}
|
|
}
|
|
}
|
|
spin_unlock(&swap_lock);
|
|
if (bdev)
|
|
bdput(bdev);
|
|
|
|
return -ENODEV;
|
|
}
|
|
|
|
/*
|
|
* Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
|
|
* corresponding to given index in swap_info (swap type).
|
|
*/
|
|
sector_t swapdev_block(int type, pgoff_t offset)
|
|
{
|
|
struct block_device *bdev;
|
|
|
|
if ((unsigned int)type >= nr_swapfiles)
|
|
return 0;
|
|
if (!(swap_info[type]->flags & SWP_WRITEOK))
|
|
return 0;
|
|
return map_swap_entry(swp_entry(type, offset), &bdev);
|
|
}
|
|
|
|
/*
|
|
* Return either the total number of swap pages of given type, or the number
|
|
* of free pages of that type (depending on @free)
|
|
*
|
|
* This is needed for software suspend
|
|
*/
|
|
unsigned int count_swap_pages(int type, int free)
|
|
{
|
|
unsigned int n = 0;
|
|
|
|
spin_lock(&swap_lock);
|
|
if ((unsigned int)type < nr_swapfiles) {
|
|
struct swap_info_struct *sis = swap_info[type];
|
|
|
|
spin_lock(&sis->lock);
|
|
if (sis->flags & SWP_WRITEOK) {
|
|
n = sis->pages;
|
|
if (free)
|
|
n -= sis->inuse_pages;
|
|
}
|
|
spin_unlock(&sis->lock);
|
|
}
|
|
spin_unlock(&swap_lock);
|
|
return n;
|
|
}
|
|
#endif /* CONFIG_HIBERNATION */
|
|
|
|
static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte)
|
|
{
|
|
return pte_same(pte_swp_clear_soft_dirty(pte), swp_pte);
|
|
}
|
|
|
|
/*
|
|
* No need to decide whether this PTE shares the swap entry with others,
|
|
* just let do_wp_page work it out if a write is requested later - to
|
|
* force COW, vm_page_prot omits write permission from any private vma.
|
|
*/
|
|
static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long addr, swp_entry_t entry, struct page *page)
|
|
{
|
|
struct page *swapcache;
|
|
struct mem_cgroup *memcg;
|
|
spinlock_t *ptl;
|
|
pte_t *pte;
|
|
int ret = 1;
|
|
|
|
swapcache = page;
|
|
page = ksm_might_need_to_copy(page, vma, addr);
|
|
if (unlikely(!page))
|
|
return -ENOMEM;
|
|
|
|
if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
|
|
&memcg, false)) {
|
|
ret = -ENOMEM;
|
|
goto out_nolock;
|
|
}
|
|
|
|
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
|
|
if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {
|
|
mem_cgroup_cancel_charge(page, memcg, false);
|
|
ret = 0;
|
|
goto out;
|
|
}
|
|
|
|
dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
|
|
inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
|
|
get_page(page);
|
|
set_pte_at(vma->vm_mm, addr, pte,
|
|
pte_mkold(mk_pte(page, vma->vm_page_prot)));
|
|
if (page == swapcache) {
|
|
page_add_anon_rmap(page, vma, addr, false);
|
|
mem_cgroup_commit_charge(page, memcg, true, false);
|
|
} else { /* ksm created a completely new copy */
|
|
page_add_new_anon_rmap(page, vma, addr, false);
|
|
mem_cgroup_commit_charge(page, memcg, false, false);
|
|
lru_cache_add_active_or_unevictable(page, vma);
|
|
}
|
|
swap_free(entry);
|
|
/*
|
|
* Move the page to the active list so it is not
|
|
* immediately swapped out again after swapon.
|
|
*/
|
|
activate_page(page);
|
|
out:
|
|
pte_unmap_unlock(pte, ptl);
|
|
out_nolock:
|
|
if (page != swapcache) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long addr, unsigned long end,
|
|
swp_entry_t entry, struct page *page)
|
|
{
|
|
pte_t swp_pte = swp_entry_to_pte(entry);
|
|
pte_t *pte;
|
|
int ret = 0;
|
|
|
|
/*
|
|
* We don't actually need pte lock while scanning for swp_pte: since
|
|
* we hold page lock and mmap_sem, swp_pte cannot be inserted into the
|
|
* page table while we're scanning; though it could get zapped, and on
|
|
* some architectures (e.g. x86_32 with PAE) we might catch a glimpse
|
|
* of unmatched parts which look like swp_pte, so unuse_pte must
|
|
* recheck under pte lock. Scanning without pte lock lets it be
|
|
* preemptable whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
|
|
*/
|
|
pte = pte_offset_map(pmd, addr);
|
|
do {
|
|
/*
|
|
* swapoff spends a _lot_ of time in this loop!
|
|
* Test inline before going to call unuse_pte.
|
|
*/
|
|
if (unlikely(pte_same_as_swp(*pte, swp_pte))) {
|
|
pte_unmap(pte);
|
|
ret = unuse_pte(vma, pmd, addr, entry, page);
|
|
if (ret)
|
|
goto out;
|
|
pte = pte_offset_map(pmd, addr);
|
|
}
|
|
} while (pte++, addr += PAGE_SIZE, addr != end);
|
|
pte_unmap(pte - 1);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
|
|
unsigned long addr, unsigned long end,
|
|
swp_entry_t entry, struct page *page)
|
|
{
|
|
pmd_t *pmd;
|
|
unsigned long next;
|
|
int ret;
|
|
|
|
pmd = pmd_offset(pud, addr);
|
|
do {
|
|
cond_resched();
|
|
next = pmd_addr_end(addr, end);
|
|
if (pmd_none_or_trans_huge_or_clear_bad(pmd))
|
|
continue;
|
|
ret = unuse_pte_range(vma, pmd, addr, next, entry, page);
|
|
if (ret)
|
|
return ret;
|
|
} while (pmd++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static inline int unuse_pud_range(struct vm_area_struct *vma, p4d_t *p4d,
|
|
unsigned long addr, unsigned long end,
|
|
swp_entry_t entry, struct page *page)
|
|
{
|
|
pud_t *pud;
|
|
unsigned long next;
|
|
int ret;
|
|
|
|
pud = pud_offset(p4d, addr);
|
|
do {
|
|
next = pud_addr_end(addr, end);
|
|
if (pud_none_or_clear_bad(pud))
|
|
continue;
|
|
ret = unuse_pmd_range(vma, pud, addr, next, entry, page);
|
|
if (ret)
|
|
return ret;
|
|
} while (pud++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static inline int unuse_p4d_range(struct vm_area_struct *vma, pgd_t *pgd,
|
|
unsigned long addr, unsigned long end,
|
|
swp_entry_t entry, struct page *page)
|
|
{
|
|
p4d_t *p4d;
|
|
unsigned long next;
|
|
int ret;
|
|
|
|
p4d = p4d_offset(pgd, addr);
|
|
do {
|
|
next = p4d_addr_end(addr, end);
|
|
if (p4d_none_or_clear_bad(p4d))
|
|
continue;
|
|
ret = unuse_pud_range(vma, p4d, addr, next, entry, page);
|
|
if (ret)
|
|
return ret;
|
|
} while (p4d++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static int unuse_vma(struct vm_area_struct *vma,
|
|
swp_entry_t entry, struct page *page)
|
|
{
|
|
pgd_t *pgd;
|
|
unsigned long addr, end, next;
|
|
int ret;
|
|
|
|
if (page_anon_vma(page)) {
|
|
addr = page_address_in_vma(page, vma);
|
|
if (addr == -EFAULT)
|
|
return 0;
|
|
else
|
|
end = addr + PAGE_SIZE;
|
|
} else {
|
|
addr = vma->vm_start;
|
|
end = vma->vm_end;
|
|
}
|
|
|
|
pgd = pgd_offset(vma->vm_mm, addr);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
if (pgd_none_or_clear_bad(pgd))
|
|
continue;
|
|
ret = unuse_p4d_range(vma, pgd, addr, next, entry, page);
|
|
if (ret)
|
|
return ret;
|
|
} while (pgd++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static int unuse_mm(struct mm_struct *mm,
|
|
swp_entry_t entry, struct page *page)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
int ret = 0;
|
|
|
|
if (!down_read_trylock(&mm->mmap_sem)) {
|
|
/*
|
|
* Activate page so shrink_inactive_list is unlikely to unmap
|
|
* its ptes while lock is dropped, so swapoff can make progress.
|
|
*/
|
|
activate_page(page);
|
|
unlock_page(page);
|
|
down_read(&mm->mmap_sem);
|
|
lock_page(page);
|
|
}
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (vma->anon_vma && (ret = unuse_vma(vma, entry, page)))
|
|
break;
|
|
cond_resched();
|
|
}
|
|
up_read(&mm->mmap_sem);
|
|
return (ret < 0)? ret: 0;
|
|
}
|
|
|
|
/*
|
|
* Scan swap_map (or frontswap_map if frontswap parameter is true)
|
|
* from current position to next entry still in use.
|
|
* Recycle to start on reaching the end, returning 0 when empty.
|
|
*/
|
|
static unsigned int find_next_to_unuse(struct swap_info_struct *si,
|
|
unsigned int prev, bool frontswap)
|
|
{
|
|
unsigned int max = si->max;
|
|
unsigned int i = prev;
|
|
unsigned char count;
|
|
|
|
/*
|
|
* No need for swap_lock here: we're just looking
|
|
* for whether an entry is in use, not modifying it; false
|
|
* hits are okay, and sys_swapoff() has already prevented new
|
|
* allocations from this area (while holding swap_lock).
|
|
*/
|
|
for (;;) {
|
|
if (++i >= max) {
|
|
if (!prev) {
|
|
i = 0;
|
|
break;
|
|
}
|
|
/*
|
|
* No entries in use at top of swap_map,
|
|
* loop back to start and recheck there.
|
|
*/
|
|
max = prev + 1;
|
|
prev = 0;
|
|
i = 1;
|
|
}
|
|
count = READ_ONCE(si->swap_map[i]);
|
|
if (count && swap_count(count) != SWAP_MAP_BAD)
|
|
if (!frontswap || frontswap_test(si, i))
|
|
break;
|
|
if ((i % LATENCY_LIMIT) == 0)
|
|
cond_resched();
|
|
}
|
|
return i;
|
|
}
|
|
|
|
/*
|
|
* We completely avoid races by reading each swap page in advance,
|
|
* and then search for the process using it. All the necessary
|
|
* page table adjustments can then be made atomically.
|
|
*
|
|
* if the boolean frontswap is true, only unuse pages_to_unuse pages;
|
|
* pages_to_unuse==0 means all pages; ignored if frontswap is false
|
|
*/
|
|
int try_to_unuse(unsigned int type, bool frontswap,
|
|
unsigned long pages_to_unuse)
|
|
{
|
|
struct swap_info_struct *si = swap_info[type];
|
|
struct mm_struct *start_mm;
|
|
volatile unsigned char *swap_map; /* swap_map is accessed without
|
|
* locking. Mark it as volatile
|
|
* to prevent compiler doing
|
|
* something odd.
|
|
*/
|
|
unsigned char swcount;
|
|
struct page *page;
|
|
swp_entry_t entry;
|
|
unsigned int i = 0;
|
|
int retval = 0;
|
|
|
|
/*
|
|
* When searching mms for an entry, a good strategy is to
|
|
* start at the first mm we freed the previous entry from
|
|
* (though actually we don't notice whether we or coincidence
|
|
* freed the entry). Initialize this start_mm with a hold.
|
|
*
|
|
* A simpler strategy would be to start at the last mm we
|
|
* freed the previous entry from; but that would take less
|
|
* advantage of mmlist ordering, which clusters forked mms
|
|
* together, child after parent. If we race with dup_mmap(), we
|
|
* prefer to resolve parent before child, lest we miss entries
|
|
* duplicated after we scanned child: using last mm would invert
|
|
* that.
|
|
*/
|
|
start_mm = &init_mm;
|
|
mmget(&init_mm);
|
|
|
|
/*
|
|
* Keep on scanning until all entries have gone. Usually,
|
|
* one pass through swap_map is enough, but not necessarily:
|
|
* there are races when an instance of an entry might be missed.
|
|
*/
|
|
while ((i = find_next_to_unuse(si, i, frontswap)) != 0) {
|
|
if (signal_pending(current)) {
|
|
retval = -EINTR;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Get a page for the entry, using the existing swap
|
|
* cache page if there is one. Otherwise, get a clean
|
|
* page and read the swap into it.
|
|
*/
|
|
swap_map = &si->swap_map[i];
|
|
entry = swp_entry(type, i);
|
|
page = read_swap_cache_async(entry,
|
|
GFP_HIGHUSER_MOVABLE, NULL, 0, false);
|
|
if (!page) {
|
|
/*
|
|
* Either swap_duplicate() failed because entry
|
|
* has been freed independently, and will not be
|
|
* reused since sys_swapoff() already disabled
|
|
* allocation from here, or alloc_page() failed.
|
|
*/
|
|
swcount = *swap_map;
|
|
/*
|
|
* We don't hold lock here, so the swap entry could be
|
|
* SWAP_MAP_BAD (when the cluster is discarding).
|
|
* Instead of fail out, We can just skip the swap
|
|
* entry because swapoff will wait for discarding
|
|
* finish anyway.
|
|
*/
|
|
if (!swcount || swcount == SWAP_MAP_BAD)
|
|
continue;
|
|
retval = -ENOMEM;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Don't hold on to start_mm if it looks like exiting.
|
|
*/
|
|
if (atomic_read(&start_mm->mm_users) == 1) {
|
|
mmput(start_mm);
|
|
start_mm = &init_mm;
|
|
mmget(&init_mm);
|
|
}
|
|
|
|
/*
|
|
* Wait for and lock page. When do_swap_page races with
|
|
* try_to_unuse, do_swap_page can handle the fault much
|
|
* faster than try_to_unuse can locate the entry. This
|
|
* apparently redundant "wait_on_page_locked" lets try_to_unuse
|
|
* defer to do_swap_page in such a case - in some tests,
|
|
* do_swap_page and try_to_unuse repeatedly compete.
|
|
*/
|
|
wait_on_page_locked(page);
|
|
wait_on_page_writeback(page);
|
|
lock_page(page);
|
|
wait_on_page_writeback(page);
|
|
|
|
/*
|
|
* Remove all references to entry.
|
|
*/
|
|
swcount = *swap_map;
|
|
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;
|
|
struct mm_struct *new_start_mm = start_mm;
|
|
struct mm_struct *prev_mm = start_mm;
|
|
struct mm_struct *mm;
|
|
|
|
mmget(new_start_mm);
|
|
mmget(prev_mm);
|
|
spin_lock(&mmlist_lock);
|
|
while (swap_count(*swap_map) && !retval &&
|
|
(p = p->next) != &start_mm->mmlist) {
|
|
mm = list_entry(p, struct mm_struct, mmlist);
|
|
if (!mmget_not_zero(mm))
|
|
continue;
|
|
spin_unlock(&mmlist_lock);
|
|
mmput(prev_mm);
|
|
prev_mm = mm;
|
|
|
|
cond_resched();
|
|
|
|
swcount = *swap_map;
|
|
if (!swap_count(swcount)) /* any usage ? */
|
|
;
|
|
else if (mm == &init_mm)
|
|
set_start_mm = 1;
|
|
else
|
|
retval = unuse_mm(mm, entry, page);
|
|
|
|
if (set_start_mm && *swap_map < swcount) {
|
|
mmput(new_start_mm);
|
|
mmget(mm);
|
|
new_start_mm = mm;
|
|
set_start_mm = 0;
|
|
}
|
|
spin_lock(&mmlist_lock);
|
|
}
|
|
spin_unlock(&mmlist_lock);
|
|
mmput(prev_mm);
|
|
mmput(start_mm);
|
|
start_mm = new_start_mm;
|
|
}
|
|
if (retval) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If a reference remains (rare), we would like to leave
|
|
* the page in the swap cache; but try_to_unmap could
|
|
* then re-duplicate the entry once we drop page lock,
|
|
* so we might loop indefinitely; also, that page could
|
|
* not be swapped out to other storage meanwhile. So:
|
|
* delete from cache even if there's another reference,
|
|
* after ensuring that the data has been saved to disk -
|
|
* since if the reference remains (rarer), it will be
|
|
* read from disk into another page. Splitting into two
|
|
* pages would be incorrect if swap supported "shared
|
|
* private" pages, but they are handled by tmpfs files.
|
|
*
|
|
* Given how unuse_vma() targets one particular offset
|
|
* in an anon_vma, once the anon_vma has been determined,
|
|
* this splitting happens to be just what is needed to
|
|
* handle where KSM pages have been swapped out: re-reading
|
|
* is unnecessarily slow, but we can fix that later on.
|
|
*/
|
|
if (swap_count(*swap_map) &&
|
|
PageDirty(page) && PageSwapCache(page)) {
|
|
struct writeback_control wbc = {
|
|
.sync_mode = WB_SYNC_NONE,
|
|
};
|
|
|
|
swap_writepage(compound_head(page), &wbc);
|
|
lock_page(page);
|
|
wait_on_page_writeback(page);
|
|
}
|
|
|
|
/*
|
|
* It is conceivable that a racing task removed this page from
|
|
* swap cache just before we acquired the page lock at the top,
|
|
* or while we dropped it in unuse_mm(). The page might even
|
|
* be back in swap cache on another swap area: that we must not
|
|
* delete, since it may not have been written out to swap yet.
|
|
*/
|
|
if (PageSwapCache(page) &&
|
|
likely(page_private(page) == entry.val) &&
|
|
!page_swapped(page))
|
|
delete_from_swap_cache(compound_head(page));
|
|
|
|
/*
|
|
* So we could skip searching mms once swap count went
|
|
* to 1, we did not mark any present ptes as dirty: must
|
|
* mark page dirty so shrink_page_list will preserve it.
|
|
*/
|
|
SetPageDirty(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
|
|
/*
|
|
* Make sure that we aren't completely killing
|
|
* interactive performance.
|
|
*/
|
|
cond_resched();
|
|
if (frontswap && pages_to_unuse > 0) {
|
|
if (!--pages_to_unuse)
|
|
break;
|
|
}
|
|
}
|
|
|
|
mmput(start_mm);
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* After a successful try_to_unuse, if no swap is now in use, we know
|
|
* we can empty the mmlist. swap_lock must be held on entry and exit.
|
|
* Note that mmlist_lock nests inside swap_lock, and an mm must be
|
|
* added to the mmlist just after page_duplicate - before would be racy.
|
|
*/
|
|
static void drain_mmlist(void)
|
|
{
|
|
struct list_head *p, *next;
|
|
unsigned int type;
|
|
|
|
for (type = 0; type < nr_swapfiles; type++)
|
|
if (swap_info[type]->inuse_pages)
|
|
return;
|
|
spin_lock(&mmlist_lock);
|
|
list_for_each_safe(p, next, &init_mm.mmlist)
|
|
list_del_init(p);
|
|
spin_unlock(&mmlist_lock);
|
|
}
|
|
|
|
/*
|
|
* Use this swapdev's extent info to locate the (PAGE_SIZE) block which
|
|
* corresponds to page offset for the specified swap entry.
|
|
* Note that the type of this function is sector_t, but it returns page offset
|
|
* into the bdev, not sector offset.
|
|
*/
|
|
static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev)
|
|
{
|
|
struct swap_info_struct *sis;
|
|
struct swap_extent *start_se;
|
|
struct swap_extent *se;
|
|
pgoff_t offset;
|
|
|
|
sis = swap_info[swp_type(entry)];
|
|
*bdev = sis->bdev;
|
|
|
|
offset = swp_offset(entry);
|
|
start_se = sis->curr_swap_extent;
|
|
se = start_se;
|
|
|
|
for ( ; ; ) {
|
|
if (se->start_page <= offset &&
|
|
offset < (se->start_page + se->nr_pages)) {
|
|
return se->start_block + (offset - se->start_page);
|
|
}
|
|
se = list_next_entry(se, list);
|
|
sis->curr_swap_extent = se;
|
|
BUG_ON(se == start_se); /* It *must* be present */
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Returns the page offset into bdev for the specified page's swap entry.
|
|
*/
|
|
sector_t map_swap_page(struct page *page, struct block_device **bdev)
|
|
{
|
|
swp_entry_t entry;
|
|
entry.val = page_private(page);
|
|
return map_swap_entry(entry, bdev);
|
|
}
|
|
|
|
/*
|
|
* Free all of a swapdev's extent information
|
|
*/
|
|
static void destroy_swap_extents(struct swap_info_struct *sis)
|
|
{
|
|
while (!list_empty(&sis->first_swap_extent.list)) {
|
|
struct swap_extent *se;
|
|
|
|
se = list_first_entry(&sis->first_swap_extent.list,
|
|
struct swap_extent, list);
|
|
list_del(&se->list);
|
|
kfree(se);
|
|
}
|
|
|
|
if (sis->flags & SWP_FILE) {
|
|
struct file *swap_file = sis->swap_file;
|
|
struct address_space *mapping = swap_file->f_mapping;
|
|
|
|
sis->flags &= ~SWP_FILE;
|
|
mapping->a_ops->swap_deactivate(swap_file);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Add a block range (and the corresponding page range) into this swapdev's
|
|
* extent list. The extent list is kept sorted in page order.
|
|
*
|
|
* This function rather assumes that it is called in ascending page order.
|
|
*/
|
|
int
|
|
add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
|
|
unsigned long nr_pages, sector_t start_block)
|
|
{
|
|
struct swap_extent *se;
|
|
struct swap_extent *new_se;
|
|
struct list_head *lh;
|
|
|
|
if (start_page == 0) {
|
|
se = &sis->first_swap_extent;
|
|
sis->curr_swap_extent = se;
|
|
se->start_page = 0;
|
|
se->nr_pages = nr_pages;
|
|
se->start_block = start_block;
|
|
return 1;
|
|
} else {
|
|
lh = sis->first_swap_extent.list.prev; /* Highest extent */
|
|
se = list_entry(lh, struct swap_extent, list);
|
|
BUG_ON(se->start_page + se->nr_pages != start_page);
|
|
if (se->start_block + se->nr_pages == start_block) {
|
|
/* Merge it */
|
|
se->nr_pages += nr_pages;
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* No merge. Insert a new extent, preserving ordering.
|
|
*/
|
|
new_se = kmalloc(sizeof(*se), GFP_KERNEL);
|
|
if (new_se == NULL)
|
|
return -ENOMEM;
|
|
new_se->start_page = start_page;
|
|
new_se->nr_pages = nr_pages;
|
|
new_se->start_block = start_block;
|
|
|
|
list_add_tail(&new_se->list, &sis->first_swap_extent.list);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* A `swap extent' is a simple thing which maps a contiguous range of pages
|
|
* onto a contiguous range of disk blocks. An ordered list of swap extents
|
|
* is built at swapon time and is then used at swap_writepage/swap_readpage
|
|
* time for locating where on disk a page belongs.
|
|
*
|
|
* If the swapfile is an S_ISBLK block device, a single extent is installed.
|
|
* This is done so that the main operating code can treat S_ISBLK and S_ISREG
|
|
* swap files identically.
|
|
*
|
|
* Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
|
|
* extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
|
|
* swapfiles are handled *identically* after swapon time.
|
|
*
|
|
* For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
|
|
* and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
|
|
* some stray blocks are found which do not fall within the PAGE_SIZE alignment
|
|
* requirements, they are simply tossed out - we will never use those blocks
|
|
* for swapping.
|
|
*
|
|
* For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
|
|
* prevents root from shooting her foot off by ftruncating an in-use swapfile,
|
|
* which will scribble on the fs.
|
|
*
|
|
* The amount of disk space which a single swap extent represents varies.
|
|
* Typically it is in the 1-4 megabyte range. So we can have hundreds of
|
|
* extents in the list. To avoid much list walking, we cache the previous
|
|
* search location in `curr_swap_extent', and start new searches from there.
|
|
* This is extremely effective. The average number of iterations in
|
|
* map_swap_page() has been measured at about 0.3 per page. - akpm.
|
|
*/
|
|
static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
|
|
{
|
|
struct file *swap_file = sis->swap_file;
|
|
struct address_space *mapping = swap_file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
int ret;
|
|
|
|
if (S_ISBLK(inode->i_mode)) {
|
|
ret = add_swap_extent(sis, 0, sis->max, 0);
|
|
*span = sis->pages;
|
|
return ret;
|
|
}
|
|
|
|
if (mapping->a_ops->swap_activate) {
|
|
ret = mapping->a_ops->swap_activate(sis, swap_file, span);
|
|
if (!ret) {
|
|
sis->flags |= SWP_FILE;
|
|
ret = add_swap_extent(sis, 0, sis->max, 0);
|
|
*span = sis->pages;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
return generic_swapfile_activate(sis, swap_file, span);
|
|
}
|
|
|
|
static int swap_node(struct swap_info_struct *p)
|
|
{
|
|
struct block_device *bdev;
|
|
|
|
if (p->bdev)
|
|
bdev = p->bdev;
|
|
else
|
|
bdev = p->swap_file->f_inode->i_sb->s_bdev;
|
|
|
|
return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE;
|
|
}
|
|
|
|
static void _enable_swap_info(struct swap_info_struct *p, int prio,
|
|
unsigned char *swap_map,
|
|
struct swap_cluster_info *cluster_info)
|
|
{
|
|
int i;
|
|
|
|
if (prio >= 0)
|
|
p->prio = prio;
|
|
else
|
|
p->prio = --least_priority;
|
|
/*
|
|
* the plist prio is negated because plist ordering is
|
|
* low-to-high, while swap ordering is high-to-low
|
|
*/
|
|
p->list.prio = -p->prio;
|
|
for_each_node(i) {
|
|
if (p->prio >= 0)
|
|
p->avail_lists[i].prio = -p->prio;
|
|
else {
|
|
if (swap_node(p) == i)
|
|
p->avail_lists[i].prio = 1;
|
|
else
|
|
p->avail_lists[i].prio = -p->prio;
|
|
}
|
|
}
|
|
p->swap_map = swap_map;
|
|
p->cluster_info = cluster_info;
|
|
p->flags |= SWP_WRITEOK;
|
|
atomic_long_add(p->pages, &nr_swap_pages);
|
|
total_swap_pages += p->pages;
|
|
|
|
assert_spin_locked(&swap_lock);
|
|
/*
|
|
* both lists are plists, and thus priority ordered.
|
|
* swap_active_head needs to be priority ordered for swapoff(),
|
|
* which on removal of any swap_info_struct with an auto-assigned
|
|
* (i.e. negative) priority increments the auto-assigned priority
|
|
* of any lower-priority swap_info_structs.
|
|
* swap_avail_head needs to be priority ordered for get_swap_page(),
|
|
* which allocates swap pages from the highest available priority
|
|
* swap_info_struct.
|
|
*/
|
|
plist_add(&p->list, &swap_active_head);
|
|
add_to_avail_list(p);
|
|
}
|
|
|
|
static void enable_swap_info(struct swap_info_struct *p, int prio,
|
|
unsigned char *swap_map,
|
|
struct swap_cluster_info *cluster_info,
|
|
unsigned long *frontswap_map)
|
|
{
|
|
frontswap_init(p->type, frontswap_map);
|
|
spin_lock(&swap_lock);
|
|
spin_lock(&p->lock);
|
|
_enable_swap_info(p, prio, swap_map, cluster_info);
|
|
spin_unlock(&p->lock);
|
|
spin_unlock(&swap_lock);
|
|
}
|
|
|
|
static void reinsert_swap_info(struct swap_info_struct *p)
|
|
{
|
|
spin_lock(&swap_lock);
|
|
spin_lock(&p->lock);
|
|
_enable_swap_info(p, p->prio, p->swap_map, p->cluster_info);
|
|
spin_unlock(&p->lock);
|
|
spin_unlock(&swap_lock);
|
|
}
|
|
|
|
bool has_usable_swap(void)
|
|
{
|
|
bool ret = true;
|
|
|
|
spin_lock(&swap_lock);
|
|
if (plist_head_empty(&swap_active_head))
|
|
ret = false;
|
|
spin_unlock(&swap_lock);
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
|
|
{
|
|
struct swap_info_struct *p = NULL;
|
|
unsigned char *swap_map;
|
|
struct swap_cluster_info *cluster_info;
|
|
unsigned long *frontswap_map;
|
|
struct file *swap_file, *victim;
|
|
struct address_space *mapping;
|
|
struct inode *inode;
|
|
struct filename *pathname;
|
|
int err, found = 0;
|
|
unsigned int old_block_size;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
BUG_ON(!current->mm);
|
|
|
|
pathname = getname(specialfile);
|
|
if (IS_ERR(pathname))
|
|
return PTR_ERR(pathname);
|
|
|
|
victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0);
|
|
err = PTR_ERR(victim);
|
|
if (IS_ERR(victim))
|
|
goto out;
|
|
|
|
mapping = victim->f_mapping;
|
|
spin_lock(&swap_lock);
|
|
plist_for_each_entry(p, &swap_active_head, list) {
|
|
if (p->flags & SWP_WRITEOK) {
|
|
if (p->swap_file->f_mapping == mapping) {
|
|
found = 1;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
if (!found) {
|
|
err = -EINVAL;
|
|
spin_unlock(&swap_lock);
|
|
goto out_dput;
|
|
}
|
|
if (!security_vm_enough_memory_mm(current->mm, p->pages))
|
|
vm_unacct_memory(p->pages);
|
|
else {
|
|
err = -ENOMEM;
|
|
spin_unlock(&swap_lock);
|
|
goto out_dput;
|
|
}
|
|
del_from_avail_list(p);
|
|
spin_lock(&p->lock);
|
|
if (p->prio < 0) {
|
|
struct swap_info_struct *si = p;
|
|
int nid;
|
|
|
|
plist_for_each_entry_continue(si, &swap_active_head, list) {
|
|
si->prio++;
|
|
si->list.prio--;
|
|
for_each_node(nid) {
|
|
if (si->avail_lists[nid].prio != 1)
|
|
si->avail_lists[nid].prio--;
|
|
}
|
|
}
|
|
least_priority++;
|
|
}
|
|
plist_del(&p->list, &swap_active_head);
|
|
atomic_long_sub(p->pages, &nr_swap_pages);
|
|
total_swap_pages -= p->pages;
|
|
p->flags &= ~SWP_WRITEOK;
|
|
spin_unlock(&p->lock);
|
|
spin_unlock(&swap_lock);
|
|
|
|
disable_swap_slots_cache_lock();
|
|
|
|
set_current_oom_origin();
|
|
err = try_to_unuse(p->type, false, 0); /* force unuse all pages */
|
|
clear_current_oom_origin();
|
|
|
|
if (err) {
|
|
/* re-insert swap space back into swap_list */
|
|
reinsert_swap_info(p);
|
|
reenable_swap_slots_cache_unlock();
|
|
goto out_dput;
|
|
}
|
|
|
|
reenable_swap_slots_cache_unlock();
|
|
|
|
flush_work(&p->discard_work);
|
|
|
|
destroy_swap_extents(p);
|
|
if (p->flags & SWP_CONTINUED)
|
|
free_swap_count_continuations(p);
|
|
|
|
if (!p->bdev || !blk_queue_nonrot(bdev_get_queue(p->bdev)))
|
|
atomic_dec(&nr_rotate_swap);
|
|
|
|
mutex_lock(&swapon_mutex);
|
|
spin_lock(&swap_lock);
|
|
spin_lock(&p->lock);
|
|
drain_mmlist();
|
|
|
|
/* wait for anyone still in scan_swap_map */
|
|
p->highest_bit = 0; /* cuts scans short */
|
|
while (p->flags >= SWP_SCANNING) {
|
|
spin_unlock(&p->lock);
|
|
spin_unlock(&swap_lock);
|
|
schedule_timeout_uninterruptible(1);
|
|
spin_lock(&swap_lock);
|
|
spin_lock(&p->lock);
|
|
}
|
|
|
|
swap_file = p->swap_file;
|
|
old_block_size = p->old_block_size;
|
|
p->swap_file = NULL;
|
|
p->max = 0;
|
|
swap_map = p->swap_map;
|
|
p->swap_map = NULL;
|
|
cluster_info = p->cluster_info;
|
|
p->cluster_info = NULL;
|
|
frontswap_map = frontswap_map_get(p);
|
|
spin_unlock(&p->lock);
|
|
spin_unlock(&swap_lock);
|
|
frontswap_invalidate_area(p->type);
|
|
frontswap_map_set(p, NULL);
|
|
mutex_unlock(&swapon_mutex);
|
|
free_percpu(p->percpu_cluster);
|
|
p->percpu_cluster = NULL;
|
|
vfree(swap_map);
|
|
kvfree(cluster_info);
|
|
kvfree(frontswap_map);
|
|
/* Destroy swap account information */
|
|
swap_cgroup_swapoff(p->type);
|
|
exit_swap_address_space(p->type);
|
|
|
|
inode = mapping->host;
|
|
if (S_ISBLK(inode->i_mode)) {
|
|
struct block_device *bdev = I_BDEV(inode);
|
|
set_blocksize(bdev, old_block_size);
|
|
blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
|
|
} else {
|
|
inode_lock(inode);
|
|
inode->i_flags &= ~S_SWAPFILE;
|
|
inode_unlock(inode);
|
|
}
|
|
filp_close(swap_file, NULL);
|
|
|
|
/*
|
|
* Clear the SWP_USED flag after all resources are freed so that swapon
|
|
* can reuse this swap_info in alloc_swap_info() safely. It is ok to
|
|
* not hold p->lock after we cleared its SWP_WRITEOK.
|
|
*/
|
|
spin_lock(&swap_lock);
|
|
p->flags = 0;
|
|
spin_unlock(&swap_lock);
|
|
|
|
err = 0;
|
|
atomic_inc(&proc_poll_event);
|
|
wake_up_interruptible(&proc_poll_wait);
|
|
|
|
out_dput:
|
|
filp_close(victim, NULL);
|
|
out:
|
|
putname(pathname);
|
|
return err;
|
|
}
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
static unsigned swaps_poll(struct file *file, poll_table *wait)
|
|
{
|
|
struct seq_file *seq = file->private_data;
|
|
|
|
poll_wait(file, &proc_poll_wait, wait);
|
|
|
|
if (seq->poll_event != atomic_read(&proc_poll_event)) {
|
|
seq->poll_event = atomic_read(&proc_poll_event);
|
|
return POLLIN | POLLRDNORM | POLLERR | POLLPRI;
|
|
}
|
|
|
|
return POLLIN | POLLRDNORM;
|
|
}
|
|
|
|
/* iterator */
|
|
static void *swap_start(struct seq_file *swap, loff_t *pos)
|
|
{
|
|
struct swap_info_struct *si;
|
|
int type;
|
|
loff_t l = *pos;
|
|
|
|
mutex_lock(&swapon_mutex);
|
|
|
|
if (!l)
|
|
return SEQ_START_TOKEN;
|
|
|
|
for (type = 0; type < nr_swapfiles; type++) {
|
|
smp_rmb(); /* read nr_swapfiles before swap_info[type] */
|
|
si = swap_info[type];
|
|
if (!(si->flags & SWP_USED) || !si->swap_map)
|
|
continue;
|
|
if (!--l)
|
|
return si;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
|
|
{
|
|
struct swap_info_struct *si = v;
|
|
int type;
|
|
|
|
if (v == SEQ_START_TOKEN)
|
|
type = 0;
|
|
else
|
|
type = si->type + 1;
|
|
|
|
for (; type < nr_swapfiles; type++) {
|
|
smp_rmb(); /* read nr_swapfiles before swap_info[type] */
|
|
si = swap_info[type];
|
|
if (!(si->flags & SWP_USED) || !si->swap_map)
|
|
continue;
|
|
++*pos;
|
|
return si;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void swap_stop(struct seq_file *swap, void *v)
|
|
{
|
|
mutex_unlock(&swapon_mutex);
|
|
}
|
|
|
|
static int swap_show(struct seq_file *swap, void *v)
|
|
{
|
|
struct swap_info_struct *si = v;
|
|
struct file *file;
|
|
int len;
|
|
|
|
if (si == SEQ_START_TOKEN) {
|
|
seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
|
|
return 0;
|
|
}
|
|
|
|
file = si->swap_file;
|
|
len = seq_file_path(swap, file, " \t\n\\");
|
|
seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
|
|
len < 40 ? 40 - len : 1, " ",
|
|
S_ISBLK(file_inode(file)->i_mode) ?
|
|
"partition" : "file\t",
|
|
si->pages << (PAGE_SHIFT - 10),
|
|
si->inuse_pages << (PAGE_SHIFT - 10),
|
|
si->prio);
|
|
return 0;
|
|
}
|
|
|
|
static const struct seq_operations swaps_op = {
|
|
.start = swap_start,
|
|
.next = swap_next,
|
|
.stop = swap_stop,
|
|
.show = swap_show
|
|
};
|
|
|
|
static int swaps_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct seq_file *seq;
|
|
int ret;
|
|
|
|
ret = seq_open(file, &swaps_op);
|
|
if (ret)
|
|
return ret;
|
|
|
|
seq = file->private_data;
|
|
seq->poll_event = atomic_read(&proc_poll_event);
|
|
return 0;
|
|
}
|
|
|
|
static const struct file_operations proc_swaps_operations = {
|
|
.open = swaps_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = seq_release,
|
|
.poll = swaps_poll,
|
|
};
|
|
|
|
static int __init procswaps_init(void)
|
|
{
|
|
proc_create("swaps", 0, NULL, &proc_swaps_operations);
|
|
return 0;
|
|
}
|
|
__initcall(procswaps_init);
|
|
#endif /* CONFIG_PROC_FS */
|
|
|
|
#ifdef MAX_SWAPFILES_CHECK
|
|
static int __init max_swapfiles_check(void)
|
|
{
|
|
MAX_SWAPFILES_CHECK();
|
|
return 0;
|
|
}
|
|
late_initcall(max_swapfiles_check);
|
|
#endif
|
|
|
|
static struct swap_info_struct *alloc_swap_info(void)
|
|
{
|
|
struct swap_info_struct *p;
|
|
unsigned int type;
|
|
int i;
|
|
|
|
p = kzalloc(sizeof(*p), GFP_KERNEL);
|
|
if (!p)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
spin_lock(&swap_lock);
|
|
for (type = 0; type < nr_swapfiles; type++) {
|
|
if (!(swap_info[type]->flags & SWP_USED))
|
|
break;
|
|
}
|
|
if (type >= MAX_SWAPFILES) {
|
|
spin_unlock(&swap_lock);
|
|
kfree(p);
|
|
return ERR_PTR(-EPERM);
|
|
}
|
|
if (type >= nr_swapfiles) {
|
|
p->type = type;
|
|
swap_info[type] = p;
|
|
/*
|
|
* Write swap_info[type] before nr_swapfiles, in case a
|
|
* racing procfs swap_start() or swap_next() is reading them.
|
|
* (We never shrink nr_swapfiles, we never free this entry.)
|
|
*/
|
|
smp_wmb();
|
|
nr_swapfiles++;
|
|
} else {
|
|
kfree(p);
|
|
p = swap_info[type];
|
|
/*
|
|
* Do not memset this entry: a racing procfs swap_next()
|
|
* would be relying on p->type to remain valid.
|
|
*/
|
|
}
|
|
INIT_LIST_HEAD(&p->first_swap_extent.list);
|
|
plist_node_init(&p->list, 0);
|
|
for_each_node(i)
|
|
plist_node_init(&p->avail_lists[i], 0);
|
|
p->flags = SWP_USED;
|
|
spin_unlock(&swap_lock);
|
|
spin_lock_init(&p->lock);
|
|
|
|
return p;
|
|
}
|
|
|
|
static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
|
|
{
|
|
int error;
|
|
|
|
if (S_ISBLK(inode->i_mode)) {
|
|
p->bdev = bdgrab(I_BDEV(inode));
|
|
error = blkdev_get(p->bdev,
|
|
FMODE_READ | FMODE_WRITE | FMODE_EXCL, p);
|
|
if (error < 0) {
|
|
p->bdev = NULL;
|
|
return error;
|
|
}
|
|
p->old_block_size = block_size(p->bdev);
|
|
error = set_blocksize(p->bdev, PAGE_SIZE);
|
|
if (error < 0)
|
|
return error;
|
|
p->flags |= SWP_BLKDEV;
|
|
} else if (S_ISREG(inode->i_mode)) {
|
|
p->bdev = inode->i_sb->s_bdev;
|
|
inode_lock(inode);
|
|
if (IS_SWAPFILE(inode))
|
|
return -EBUSY;
|
|
} else
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static unsigned long read_swap_header(struct swap_info_struct *p,
|
|
union swap_header *swap_header,
|
|
struct inode *inode)
|
|
{
|
|
int i;
|
|
unsigned long maxpages;
|
|
unsigned long swapfilepages;
|
|
unsigned long last_page;
|
|
|
|
if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
|
|
pr_err("Unable to find swap-space signature\n");
|
|
return 0;
|
|
}
|
|
|
|
/* swap partition endianess hack... */
|
|
if (swab32(swap_header->info.version) == 1) {
|
|
swab32s(&swap_header->info.version);
|
|
swab32s(&swap_header->info.last_page);
|
|
swab32s(&swap_header->info.nr_badpages);
|
|
if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
|
|
return 0;
|
|
for (i = 0; i < swap_header->info.nr_badpages; i++)
|
|
swab32s(&swap_header->info.badpages[i]);
|
|
}
|
|
/* Check the swap header's sub-version */
|
|
if (swap_header->info.version != 1) {
|
|
pr_warn("Unable to handle swap header version %d\n",
|
|
swap_header->info.version);
|
|
return 0;
|
|
}
|
|
|
|
p->lowest_bit = 1;
|
|
p->cluster_next = 1;
|
|
p->cluster_nr = 0;
|
|
|
|
/*
|
|
* 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 swap pte as defined by the
|
|
* different architectures. 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
|
|
* 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.
|
|
*/
|
|
maxpages = swp_offset(pte_to_swp_entry(
|
|
swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
|
|
last_page = swap_header->info.last_page;
|
|
if (last_page > maxpages) {
|
|
pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
|
|
maxpages << (PAGE_SHIFT - 10),
|
|
last_page << (PAGE_SHIFT - 10));
|
|
}
|
|
if (maxpages > last_page) {
|
|
maxpages = last_page + 1;
|
|
/* p->max is an unsigned int: don't overflow it */
|
|
if ((unsigned int)maxpages == 0)
|
|
maxpages = UINT_MAX;
|
|
}
|
|
p->highest_bit = maxpages - 1;
|
|
|
|
if (!maxpages)
|
|
return 0;
|
|
swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
|
|
if (swapfilepages && maxpages > swapfilepages) {
|
|
pr_warn("Swap area shorter than signature indicates\n");
|
|
return 0;
|
|
}
|
|
if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
|
|
return 0;
|
|
if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
|
|
return 0;
|
|
|
|
return maxpages;
|
|
}
|
|
|
|
#define SWAP_CLUSTER_INFO_COLS \
|
|
DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
|
|
#define SWAP_CLUSTER_SPACE_COLS \
|
|
DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
|
|
#define SWAP_CLUSTER_COLS \
|
|
max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
|
|
|
|
static int setup_swap_map_and_extents(struct swap_info_struct *p,
|
|
union swap_header *swap_header,
|
|
unsigned char *swap_map,
|
|
struct swap_cluster_info *cluster_info,
|
|
unsigned long maxpages,
|
|
sector_t *span)
|
|
{
|
|
unsigned int j, k;
|
|
unsigned int nr_good_pages;
|
|
int nr_extents;
|
|
unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
|
|
unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS;
|
|
unsigned long i, idx;
|
|
|
|
nr_good_pages = maxpages - 1; /* omit header page */
|
|
|
|
cluster_list_init(&p->free_clusters);
|
|
cluster_list_init(&p->discard_clusters);
|
|
|
|
for (i = 0; i < swap_header->info.nr_badpages; i++) {
|
|
unsigned int page_nr = swap_header->info.badpages[i];
|
|
if (page_nr == 0 || page_nr > swap_header->info.last_page)
|
|
return -EINVAL;
|
|
if (page_nr < maxpages) {
|
|
swap_map[page_nr] = SWAP_MAP_BAD;
|
|
nr_good_pages--;
|
|
/*
|
|
* Haven't marked the cluster free yet, no list
|
|
* operation involved
|
|
*/
|
|
inc_cluster_info_page(p, cluster_info, page_nr);
|
|
}
|
|
}
|
|
|
|
/* Haven't marked the cluster free yet, no list operation involved */
|
|
for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++)
|
|
inc_cluster_info_page(p, cluster_info, i);
|
|
|
|
if (nr_good_pages) {
|
|
swap_map[0] = SWAP_MAP_BAD;
|
|
/*
|
|
* Not mark the cluster free yet, no list
|
|
* operation involved
|
|
*/
|
|
inc_cluster_info_page(p, cluster_info, 0);
|
|
p->max = maxpages;
|
|
p->pages = nr_good_pages;
|
|
nr_extents = setup_swap_extents(p, span);
|
|
if (nr_extents < 0)
|
|
return nr_extents;
|
|
nr_good_pages = p->pages;
|
|
}
|
|
if (!nr_good_pages) {
|
|
pr_warn("Empty swap-file\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!cluster_info)
|
|
return nr_extents;
|
|
|
|
|
|
/*
|
|
* Reduce false cache line sharing between cluster_info and
|
|
* sharing same address space.
|
|
*/
|
|
for (k = 0; k < SWAP_CLUSTER_COLS; k++) {
|
|
j = (k + col) % SWAP_CLUSTER_COLS;
|
|
for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) {
|
|
idx = i * SWAP_CLUSTER_COLS + j;
|
|
if (idx >= nr_clusters)
|
|
continue;
|
|
if (cluster_count(&cluster_info[idx]))
|
|
continue;
|
|
cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE);
|
|
cluster_list_add_tail(&p->free_clusters, cluster_info,
|
|
idx);
|
|
}
|
|
}
|
|
return nr_extents;
|
|
}
|
|
|
|
/*
|
|
* Helper to sys_swapon determining if a given swap
|
|
* backing device queue supports DISCARD operations.
|
|
*/
|
|
static bool swap_discardable(struct swap_info_struct *si)
|
|
{
|
|
struct request_queue *q = bdev_get_queue(si->bdev);
|
|
|
|
if (!q || !blk_queue_discard(q))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
|
|
{
|
|
struct swap_info_struct *p;
|
|
struct filename *name;
|
|
struct file *swap_file = NULL;
|
|
struct address_space *mapping;
|
|
int prio;
|
|
int error;
|
|
union swap_header *swap_header;
|
|
int nr_extents;
|
|
sector_t span;
|
|
unsigned long maxpages;
|
|
unsigned char *swap_map = NULL;
|
|
struct swap_cluster_info *cluster_info = NULL;
|
|
unsigned long *frontswap_map = NULL;
|
|
struct page *page = NULL;
|
|
struct inode *inode = NULL;
|
|
|
|
if (swap_flags & ~SWAP_FLAGS_VALID)
|
|
return -EINVAL;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
if (!swap_avail_heads)
|
|
return -ENOMEM;
|
|
|
|
p = alloc_swap_info();
|
|
if (IS_ERR(p))
|
|
return PTR_ERR(p);
|
|
|
|
INIT_WORK(&p->discard_work, swap_discard_work);
|
|
|
|
name = getname(specialfile);
|
|
if (IS_ERR(name)) {
|
|
error = PTR_ERR(name);
|
|
name = NULL;
|
|
goto bad_swap;
|
|
}
|
|
swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0);
|
|
if (IS_ERR(swap_file)) {
|
|
error = PTR_ERR(swap_file);
|
|
swap_file = NULL;
|
|
goto bad_swap;
|
|
}
|
|
|
|
p->swap_file = swap_file;
|
|
mapping = swap_file->f_mapping;
|
|
inode = mapping->host;
|
|
|
|
/* If S_ISREG(inode->i_mode) will do inode_lock(inode); */
|
|
error = claim_swapfile(p, inode);
|
|
if (unlikely(error))
|
|
goto bad_swap;
|
|
|
|
/*
|
|
* Read the swap header.
|
|
*/
|
|
if (!mapping->a_ops->readpage) {
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
}
|
|
page = read_mapping_page(mapping, 0, swap_file);
|
|
if (IS_ERR(page)) {
|
|
error = PTR_ERR(page);
|
|
goto bad_swap;
|
|
}
|
|
swap_header = kmap(page);
|
|
|
|
maxpages = read_swap_header(p, swap_header, inode);
|
|
if (unlikely(!maxpages)) {
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
}
|
|
|
|
/* OK, set up the swap map and apply the bad block list */
|
|
swap_map = vzalloc(maxpages);
|
|
if (!swap_map) {
|
|
error = -ENOMEM;
|
|
goto bad_swap;
|
|
}
|
|
|
|
if (bdi_cap_stable_pages_required(inode_to_bdi(inode)))
|
|
p->flags |= SWP_STABLE_WRITES;
|
|
|
|
if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) {
|
|
int cpu;
|
|
unsigned long ci, nr_cluster;
|
|
|
|
p->flags |= SWP_SOLIDSTATE;
|
|
/*
|
|
* select a random position to start with to help wear leveling
|
|
* SSD
|
|
*/
|
|
p->cluster_next = 1 + (prandom_u32() % p->highest_bit);
|
|
nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
|
|
|
|
cluster_info = kvzalloc(nr_cluster * sizeof(*cluster_info),
|
|
GFP_KERNEL);
|
|
if (!cluster_info) {
|
|
error = -ENOMEM;
|
|
goto bad_swap;
|
|
}
|
|
|
|
for (ci = 0; ci < nr_cluster; ci++)
|
|
spin_lock_init(&((cluster_info + ci)->lock));
|
|
|
|
p->percpu_cluster = alloc_percpu(struct percpu_cluster);
|
|
if (!p->percpu_cluster) {
|
|
error = -ENOMEM;
|
|
goto bad_swap;
|
|
}
|
|
for_each_possible_cpu(cpu) {
|
|
struct percpu_cluster *cluster;
|
|
cluster = per_cpu_ptr(p->percpu_cluster, cpu);
|
|
cluster_set_null(&cluster->index);
|
|
}
|
|
} else
|
|
atomic_inc(&nr_rotate_swap);
|
|
|
|
error = swap_cgroup_swapon(p->type, maxpages);
|
|
if (error)
|
|
goto bad_swap;
|
|
|
|
nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map,
|
|
cluster_info, maxpages, &span);
|
|
if (unlikely(nr_extents < 0)) {
|
|
error = nr_extents;
|
|
goto bad_swap;
|
|
}
|
|
/* frontswap enabled? set up bit-per-page map for frontswap */
|
|
if (IS_ENABLED(CONFIG_FRONTSWAP))
|
|
frontswap_map = kvzalloc(BITS_TO_LONGS(maxpages) * sizeof(long),
|
|
GFP_KERNEL);
|
|
|
|
if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) {
|
|
/*
|
|
* When discard is enabled for swap with no particular
|
|
* policy flagged, we set all swap discard flags here in
|
|
* order to sustain backward compatibility with older
|
|
* swapon(8) releases.
|
|
*/
|
|
p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD |
|
|
SWP_PAGE_DISCARD);
|
|
|
|
/*
|
|
* By flagging sys_swapon, a sysadmin can tell us to
|
|
* either do single-time area discards only, or to just
|
|
* perform discards for released swap page-clusters.
|
|
* Now it's time to adjust the p->flags accordingly.
|
|
*/
|
|
if (swap_flags & SWAP_FLAG_DISCARD_ONCE)
|
|
p->flags &= ~SWP_PAGE_DISCARD;
|
|
else if (swap_flags & SWAP_FLAG_DISCARD_PAGES)
|
|
p->flags &= ~SWP_AREA_DISCARD;
|
|
|
|
/* issue a swapon-time discard if it's still required */
|
|
if (p->flags & SWP_AREA_DISCARD) {
|
|
int err = discard_swap(p);
|
|
if (unlikely(err))
|
|
pr_err("swapon: discard_swap(%p): %d\n",
|
|
p, err);
|
|
}
|
|
}
|
|
|
|
error = init_swap_address_space(p->type, maxpages);
|
|
if (error)
|
|
goto bad_swap;
|
|
|
|
mutex_lock(&swapon_mutex);
|
|
prio = -1;
|
|
if (swap_flags & SWAP_FLAG_PREFER)
|
|
prio =
|
|
(swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
|
|
enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map);
|
|
|
|
pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
|
|
p->pages<<(PAGE_SHIFT-10), name->name, p->prio,
|
|
nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10),
|
|
(p->flags & SWP_SOLIDSTATE) ? "SS" : "",
|
|
(p->flags & SWP_DISCARDABLE) ? "D" : "",
|
|
(p->flags & SWP_AREA_DISCARD) ? "s" : "",
|
|
(p->flags & SWP_PAGE_DISCARD) ? "c" : "",
|
|
(frontswap_map) ? "FS" : "");
|
|
|
|
mutex_unlock(&swapon_mutex);
|
|
atomic_inc(&proc_poll_event);
|
|
wake_up_interruptible(&proc_poll_wait);
|
|
|
|
if (S_ISREG(inode->i_mode))
|
|
inode->i_flags |= S_SWAPFILE;
|
|
error = 0;
|
|
goto out;
|
|
bad_swap:
|
|
free_percpu(p->percpu_cluster);
|
|
p->percpu_cluster = NULL;
|
|
if (inode && S_ISBLK(inode->i_mode) && p->bdev) {
|
|
set_blocksize(p->bdev, p->old_block_size);
|
|
blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
|
|
}
|
|
destroy_swap_extents(p);
|
|
swap_cgroup_swapoff(p->type);
|
|
spin_lock(&swap_lock);
|
|
p->swap_file = NULL;
|
|
p->flags = 0;
|
|
spin_unlock(&swap_lock);
|
|
vfree(swap_map);
|
|
kvfree(cluster_info);
|
|
kvfree(frontswap_map);
|
|
if (swap_file) {
|
|
if (inode && S_ISREG(inode->i_mode)) {
|
|
inode_unlock(inode);
|
|
inode = NULL;
|
|
}
|
|
filp_close(swap_file, NULL);
|
|
}
|
|
out:
|
|
if (page && !IS_ERR(page)) {
|
|
kunmap(page);
|
|
put_page(page);
|
|
}
|
|
if (name)
|
|
putname(name);
|
|
if (inode && S_ISREG(inode->i_mode))
|
|
inode_unlock(inode);
|
|
if (!error)
|
|
enable_swap_slots_cache();
|
|
return error;
|
|
}
|
|
|
|
void si_swapinfo(struct sysinfo *val)
|
|
{
|
|
unsigned int type;
|
|
unsigned long nr_to_be_unused = 0;
|
|
|
|
spin_lock(&swap_lock);
|
|
for (type = 0; type < nr_swapfiles; type++) {
|
|
struct swap_info_struct *si = swap_info[type];
|
|
|
|
if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK))
|
|
nr_to_be_unused += si->inuse_pages;
|
|
}
|
|
val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused;
|
|
val->totalswap = total_swap_pages + nr_to_be_unused;
|
|
spin_unlock(&swap_lock);
|
|
}
|
|
|
|
/*
|
|
* Verify that a swap entry is valid and increment its swap map count.
|
|
*
|
|
* Returns error code in following case.
|
|
* - success -> 0
|
|
* - swp_entry is invalid -> EINVAL
|
|
* - swp_entry is migration entry -> EINVAL
|
|
* - swap-cache reference is requested but there is already one. -> EEXIST
|
|
* - swap-cache reference is requested but the entry is not used. -> ENOENT
|
|
* - swap-mapped reference requested but needs continued swap count. -> ENOMEM
|
|
*/
|
|
static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
|
|
{
|
|
struct swap_info_struct *p;
|
|
struct swap_cluster_info *ci;
|
|
unsigned long offset, type;
|
|
unsigned char count;
|
|
unsigned char has_cache;
|
|
int err = -EINVAL;
|
|
|
|
if (non_swap_entry(entry))
|
|
goto out;
|
|
|
|
type = swp_type(entry);
|
|
if (type >= nr_swapfiles)
|
|
goto bad_file;
|
|
p = swap_info[type];
|
|
offset = swp_offset(entry);
|
|
if (unlikely(offset >= p->max))
|
|
goto out;
|
|
|
|
ci = lock_cluster_or_swap_info(p, offset);
|
|
|
|
count = p->swap_map[offset];
|
|
|
|
/*
|
|
* swapin_readahead() doesn't check if a swap entry is valid, so the
|
|
* swap entry could be SWAP_MAP_BAD. Check here with lock held.
|
|
*/
|
|
if (unlikely(swap_count(count) == SWAP_MAP_BAD)) {
|
|
err = -ENOENT;
|
|
goto unlock_out;
|
|
}
|
|
|
|
has_cache = count & SWAP_HAS_CACHE;
|
|
count &= ~SWAP_HAS_CACHE;
|
|
err = 0;
|
|
|
|
if (usage == SWAP_HAS_CACHE) {
|
|
|
|
/* set SWAP_HAS_CACHE if there is no cache and entry is used */
|
|
if (!has_cache && count)
|
|
has_cache = SWAP_HAS_CACHE;
|
|
else if (has_cache) /* someone else added cache */
|
|
err = -EEXIST;
|
|
else /* no users remaining */
|
|
err = -ENOENT;
|
|
|
|
} else if (count || has_cache) {
|
|
|
|
if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX)
|
|
count += usage;
|
|
else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX)
|
|
err = -EINVAL;
|
|
else if (swap_count_continued(p, offset, count))
|
|
count = COUNT_CONTINUED;
|
|
else
|
|
err = -ENOMEM;
|
|
} else
|
|
err = -ENOENT; /* unused swap entry */
|
|
|
|
p->swap_map[offset] = count | has_cache;
|
|
|
|
unlock_out:
|
|
unlock_cluster_or_swap_info(p, ci);
|
|
out:
|
|
return err;
|
|
|
|
bad_file:
|
|
pr_err("swap_dup: %s%08lx\n", Bad_file, entry.val);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
* Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
|
|
* but could not be atomically allocated. Returns 0, just as if it succeeded,
|
|
* if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
|
|
* might occur if a page table entry has got corrupted.
|
|
*/
|
|
int swap_duplicate(swp_entry_t entry)
|
|
{
|
|
int err = 0;
|
|
|
|
while (!err && __swap_duplicate(entry, 1) == -ENOMEM)
|
|
err = add_swap_count_continuation(entry, GFP_ATOMIC);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* @entry: swap entry for which we allocate swap cache.
|
|
*
|
|
* Called when allocating swap cache for existing swap entry,
|
|
* This can return error codes. Returns 0 at success.
|
|
* -EBUSY means there is a swap cache.
|
|
* Note: return code is different from swap_duplicate().
|
|
*/
|
|
int swapcache_prepare(swp_entry_t entry)
|
|
{
|
|
return __swap_duplicate(entry, SWAP_HAS_CACHE);
|
|
}
|
|
|
|
struct swap_info_struct *page_swap_info(struct page *page)
|
|
{
|
|
swp_entry_t swap = { .val = page_private(page) };
|
|
return swap_info[swp_type(swap)];
|
|
}
|
|
|
|
/*
|
|
* out-of-line __page_file_ methods to avoid include hell.
|
|
*/
|
|
struct address_space *__page_file_mapping(struct page *page)
|
|
{
|
|
VM_BUG_ON_PAGE(!PageSwapCache(page), page);
|
|
return page_swap_info(page)->swap_file->f_mapping;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__page_file_mapping);
|
|
|
|
pgoff_t __page_file_index(struct page *page)
|
|
{
|
|
swp_entry_t swap = { .val = page_private(page) };
|
|
VM_BUG_ON_PAGE(!PageSwapCache(page), page);
|
|
return swp_offset(swap);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__page_file_index);
|
|
|
|
/*
|
|
* add_swap_count_continuation - called when a swap count is duplicated
|
|
* beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
|
|
* page of the original vmalloc'ed swap_map, to hold the continuation count
|
|
* (for that entry and for its neighbouring PAGE_SIZE swap entries). Called
|
|
* again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
|
|
*
|
|
* These continuation pages are seldom referenced: the common paths all work
|
|
* on the original swap_map, only referring to a continuation page when the
|
|
* low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
|
|
*
|
|
* add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
|
|
* page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
|
|
* can be called after dropping locks.
|
|
*/
|
|
int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
|
|
{
|
|
struct swap_info_struct *si;
|
|
struct swap_cluster_info *ci;
|
|
struct page *head;
|
|
struct page *page;
|
|
struct page *list_page;
|
|
pgoff_t offset;
|
|
unsigned char count;
|
|
|
|
/*
|
|
* When debugging, it's easier to use __GFP_ZERO here; but it's better
|
|
* for latency not to zero a page while GFP_ATOMIC and holding locks.
|
|
*/
|
|
page = alloc_page(gfp_mask | __GFP_HIGHMEM);
|
|
|
|
si = swap_info_get(entry);
|
|
if (!si) {
|
|
/*
|
|
* An acceptable race has occurred since the failing
|
|
* __swap_duplicate(): the swap entry has been freed,
|
|
* perhaps even the whole swap_map cleared for swapoff.
|
|
*/
|
|
goto outer;
|
|
}
|
|
|
|
offset = swp_offset(entry);
|
|
|
|
ci = lock_cluster(si, offset);
|
|
|
|
count = si->swap_map[offset] & ~SWAP_HAS_CACHE;
|
|
|
|
if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) {
|
|
/*
|
|
* The higher the swap count, the more likely it is that tasks
|
|
* will race to add swap count continuation: we need to avoid
|
|
* over-provisioning.
|
|
*/
|
|
goto out;
|
|
}
|
|
|
|
if (!page) {
|
|
unlock_cluster(ci);
|
|
spin_unlock(&si->lock);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* We are fortunate that although vmalloc_to_page uses pte_offset_map,
|
|
* no architecture is using highmem pages for kernel page tables: so it
|
|
* will not corrupt the GFP_ATOMIC caller's atomic page table kmaps.
|
|
*/
|
|
head = vmalloc_to_page(si->swap_map + offset);
|
|
offset &= ~PAGE_MASK;
|
|
|
|
/*
|
|
* Page allocation does not initialize the page's lru field,
|
|
* but it does always reset its private field.
|
|
*/
|
|
if (!page_private(head)) {
|
|
BUG_ON(count & COUNT_CONTINUED);
|
|
INIT_LIST_HEAD(&head->lru);
|
|
set_page_private(head, SWP_CONTINUED);
|
|
si->flags |= SWP_CONTINUED;
|
|
}
|
|
|
|
list_for_each_entry(list_page, &head->lru, lru) {
|
|
unsigned char *map;
|
|
|
|
/*
|
|
* If the previous map said no continuation, but we've found
|
|
* a continuation page, free our allocation and use this one.
|
|
*/
|
|
if (!(count & COUNT_CONTINUED))
|
|
goto out;
|
|
|
|
map = kmap_atomic(list_page) + offset;
|
|
count = *map;
|
|
kunmap_atomic(map);
|
|
|
|
/*
|
|
* If this continuation count now has some space in it,
|
|
* free our allocation and use this one.
|
|
*/
|
|
if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX)
|
|
goto out;
|
|
}
|
|
|
|
list_add_tail(&page->lru, &head->lru);
|
|
page = NULL; /* now it's attached, don't free it */
|
|
out:
|
|
unlock_cluster(ci);
|
|
spin_unlock(&si->lock);
|
|
outer:
|
|
if (page)
|
|
__free_page(page);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* swap_count_continued - when the original swap_map count is incremented
|
|
* from SWAP_MAP_MAX, check if there is already a continuation page to carry
|
|
* into, carry if so, or else fail until a new continuation page is allocated;
|
|
* when the original swap_map count is decremented from 0 with continuation,
|
|
* borrow from the continuation and report whether it still holds more.
|
|
* Called while __swap_duplicate() or swap_entry_free() holds swap or cluster
|
|
* lock.
|
|
*/
|
|
static bool swap_count_continued(struct swap_info_struct *si,
|
|
pgoff_t offset, unsigned char count)
|
|
{
|
|
struct page *head;
|
|
struct page *page;
|
|
unsigned char *map;
|
|
|
|
head = vmalloc_to_page(si->swap_map + offset);
|
|
if (page_private(head) != SWP_CONTINUED) {
|
|
BUG_ON(count & COUNT_CONTINUED);
|
|
return false; /* need to add count continuation */
|
|
}
|
|
|
|
offset &= ~PAGE_MASK;
|
|
page = list_entry(head->lru.next, struct page, lru);
|
|
map = kmap_atomic(page) + offset;
|
|
|
|
if (count == SWAP_MAP_MAX) /* initial increment from swap_map */
|
|
goto init_map; /* jump over SWAP_CONT_MAX checks */
|
|
|
|
if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */
|
|
/*
|
|
* Think of how you add 1 to 999
|
|
*/
|
|
while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) {
|
|
kunmap_atomic(map);
|
|
page = list_entry(page->lru.next, struct page, lru);
|
|
BUG_ON(page == head);
|
|
map = kmap_atomic(page) + offset;
|
|
}
|
|
if (*map == SWAP_CONT_MAX) {
|
|
kunmap_atomic(map);
|
|
page = list_entry(page->lru.next, struct page, lru);
|
|
if (page == head)
|
|
return false; /* add count continuation */
|
|
map = kmap_atomic(page) + offset;
|
|
init_map: *map = 0; /* we didn't zero the page */
|
|
}
|
|
*map += 1;
|
|
kunmap_atomic(map);
|
|
page = list_entry(page->lru.prev, struct page, lru);
|
|
while (page != head) {
|
|
map = kmap_atomic(page) + offset;
|
|
*map = COUNT_CONTINUED;
|
|
kunmap_atomic(map);
|
|
page = list_entry(page->lru.prev, struct page, lru);
|
|
}
|
|
return true; /* incremented */
|
|
|
|
} else { /* decrementing */
|
|
/*
|
|
* Think of how you subtract 1 from 1000
|
|
*/
|
|
BUG_ON(count != COUNT_CONTINUED);
|
|
while (*map == COUNT_CONTINUED) {
|
|
kunmap_atomic(map);
|
|
page = list_entry(page->lru.next, struct page, lru);
|
|
BUG_ON(page == head);
|
|
map = kmap_atomic(page) + offset;
|
|
}
|
|
BUG_ON(*map == 0);
|
|
*map -= 1;
|
|
if (*map == 0)
|
|
count = 0;
|
|
kunmap_atomic(map);
|
|
page = list_entry(page->lru.prev, struct page, lru);
|
|
while (page != head) {
|
|
map = kmap_atomic(page) + offset;
|
|
*map = SWAP_CONT_MAX | count;
|
|
count = COUNT_CONTINUED;
|
|
kunmap_atomic(map);
|
|
page = list_entry(page->lru.prev, struct page, lru);
|
|
}
|
|
return count == COUNT_CONTINUED;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* free_swap_count_continuations - swapoff free all the continuation pages
|
|
* appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
|
|
*/
|
|
static void free_swap_count_continuations(struct swap_info_struct *si)
|
|
{
|
|
pgoff_t offset;
|
|
|
|
for (offset = 0; offset < si->max; offset += PAGE_SIZE) {
|
|
struct page *head;
|
|
head = vmalloc_to_page(si->swap_map + offset);
|
|
if (page_private(head)) {
|
|
struct page *page, *next;
|
|
|
|
list_for_each_entry_safe(page, next, &head->lru, lru) {
|
|
list_del(&page->lru);
|
|
__free_page(page);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
static int __init swapfile_init(void)
|
|
{
|
|
int nid;
|
|
|
|
swap_avail_heads = kmalloc_array(nr_node_ids, sizeof(struct plist_head),
|
|
GFP_KERNEL);
|
|
if (!swap_avail_heads) {
|
|
pr_emerg("Not enough memory for swap heads, swap is disabled\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
for_each_node(nid)
|
|
plist_head_init(&swap_avail_heads[nid]);
|
|
|
|
return 0;
|
|
}
|
|
subsys_initcall(swapfile_init);
|