diff options
Diffstat (limited to 'mm/swapfile.c')
| -rw-r--r-- | mm/swapfile.c | 78 |
1 files changed, 70 insertions, 8 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 03aa2d55f1a2..67ddaaf98c74 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -30,6 +30,7 @@ #include <linux/capability.h> #include <linux/syscalls.h> #include <linux/memcontrol.h> +#include <linux/poll.h> #include <asm/pgtable.h> #include <asm/tlbflush.h> @@ -58,6 +59,10 @@ static struct swap_info_struct *swap_info[MAX_SWAPFILES]; static DEFINE_MUTEX(swapon_mutex); +static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); +/* Activity counter to indicate that a swapon or swapoff has occurred */ +static atomic_t proc_poll_event = ATOMIC_INIT(0); + static inline unsigned char swap_count(unsigned char ent) { return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ @@ -139,8 +144,7 @@ static int discard_swap(struct swap_info_struct *si) nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); if (nr_blocks) { err = blkdev_issue_discard(si->bdev, start_block, - nr_blocks, GFP_KERNEL, - BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER); + nr_blocks, GFP_KERNEL, 0); if (err) return err; cond_resched(); @@ -151,8 +155,7 @@ static int discard_swap(struct swap_info_struct *si) nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); err = blkdev_issue_discard(si->bdev, start_block, - nr_blocks, GFP_KERNEL, - BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER); + nr_blocks, GFP_KERNEL, 0); if (err) break; @@ -191,8 +194,7 @@ static void discard_swap_cluster(struct swap_info_struct *si, start_block <<= PAGE_SHIFT - 9; nr_blocks <<= PAGE_SHIFT - 9; if (blkdev_issue_discard(si->bdev, start_block, - nr_blocks, GFP_NOIO, BLKDEV_IFL_WAIT | - BLKDEV_IFL_BARRIER)) + nr_blocks, GFP_NOIO, 0)) break; } @@ -686,6 +688,24 @@ int try_to_free_swap(struct page *page) if (page_swapcount(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 clears bits from gfp_allowed_mask to prevent + * memory reclaim from writing to disk, so check that here. + */ + if (!(gfp_allowed_mask & __GFP_IO)) + return 0; + delete_from_swap_cache(page); SetPageDirty(page); return 1; @@ -1665,6 +1685,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) } filp_close(swap_file, NULL); err = 0; + atomic_inc(&proc_poll_event); + wake_up_interruptible(&proc_poll_wait); out_dput: filp_close(victim, NULL); @@ -1673,6 +1695,25 @@ out: } #ifdef CONFIG_PROC_FS +struct proc_swaps { + struct seq_file seq; + int event; +}; + +static unsigned swaps_poll(struct file *file, poll_table *wait) +{ + struct proc_swaps *s = file->private_data; + + poll_wait(file, &proc_poll_wait, wait); + + if (s->event != atomic_read(&proc_poll_event)) { + s->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) { @@ -1756,7 +1797,24 @@ static const struct seq_operations swaps_op = { static int swaps_open(struct inode *inode, struct file *file) { - return seq_open(file, &swaps_op); + struct proc_swaps *s; + int ret; + + s = kmalloc(sizeof(struct proc_swaps), GFP_KERNEL); + if (!s) + return -ENOMEM; + + file->private_data = s; + + ret = seq_open(file, &swaps_op); + if (ret) { + kfree(s); + return ret; + } + + s->seq.private = s; + s->event = atomic_read(&proc_poll_event); + return ret; } static const struct file_operations proc_swaps_operations = { @@ -1764,6 +1822,7 @@ static const struct file_operations proc_swaps_operations = { .read = seq_read, .llseek = seq_lseek, .release = seq_release, + .poll = swaps_poll, }; static int __init procswaps_init(void) @@ -2032,7 +2091,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) p->flags |= SWP_SOLIDSTATE; p->cluster_next = 1 + (random32() % p->highest_bit); } - if (discard_swap(p) == 0) + if (discard_swap(p) == 0 && (swap_flags & SWAP_FLAG_DISCARD)) p->flags |= SWP_DISCARDABLE; } @@ -2069,6 +2128,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) swap_info[prev]->next = type; spin_unlock(&swap_lock); mutex_unlock(&swapon_mutex); + atomic_inc(&proc_poll_event); + wake_up_interruptible(&proc_poll_wait); + error = 0; goto out; bad_swap: |