#include <linux/rmap.h>
#include <linux/security.h>
#include <linux/backing-dev.h>
+#include <linux/syscalls.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <linux/swapops.h>
-#include <linux/vs_base.h>
+#include <linux/vs_memory.h>
spinlock_t swaplock = SPIN_LOCK_UNLOCKED;
unsigned int nr_swapfiles;
check_next_cluster:
if (offset+SWAPFILE_CLUSTER-1 <= si->highest_bit)
{
- int nr;
+ unsigned long nr;
for (nr = offset; nr < offset+SWAPFILE_CLUSTER; nr++)
if (si->swap_map[nr])
{
}
/* vma->vm_mm->page_table_lock is held */
-static unsigned long unuse_vma(struct vm_area_struct * vma, pgd_t *pgdir,
+static unsigned long unuse_vma(struct vm_area_struct * vma,
swp_entry_t entry, struct page *page)
{
- unsigned long start = vma->vm_start, end = vma->vm_end;
+ pgd_t *pgdir;
+ unsigned long start, end;
unsigned long foundaddr;
- if (start >= end)
- BUG();
+ if (page->mapping) {
+ start = page_address_in_vma(page, vma);
+ if (start == -EFAULT)
+ return 0;
+ else
+ end = start + PAGE_SIZE;
+ } else {
+ start = vma->vm_start;
+ end = vma->vm_end;
+ }
+ pgdir = pgd_offset(vma->vm_mm, start);
do {
foundaddr = unuse_pgd(vma, pgdir, start, end - start,
entry, page);
/*
* Go through process' page directory.
*/
- down_read(&mm->mmap_sem);
+ if (!down_read_trylock(&mm->mmap_sem)) {
+ /*
+ * Our reference to the page stops try_to_unmap_one from
+ * unmapping its ptes, so swapoff can make progress.
+ */
+ unlock_page(page);
+ down_read(&mm->mmap_sem);
+ lock_page(page);
+ }
spin_lock(&mm->page_table_lock);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
- if (!is_vm_hugetlb_page(vma)) {
- pgd_t * pgd = pgd_offset(mm, vma->vm_start);
- foundaddr = unuse_vma(vma, pgd, entry, page);
+ if (vma->anon_vma) {
+ foundaddr = unuse_vma(vma, entry, page);
if (foundaddr)
break;
}
*
* 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 (now preserved by swap_out()),
- * which clusters forked address spaces together, most recent
- * child immediately after parent. If we race with dup_mmap(),
- * we very much want to resolve parent before child, otherwise
- * we may miss some entries: using last mm would invert that.
+ * 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. Though it's only a serious concern when an overflowed
+ * swap count is reset from SWAP_MAP_MAX, preventing a rescan.
*/
start_mm = &init_mm;
atomic_inc(&init_mm.mm_users);
/*
* Keep on scanning until all entries have gone. Usually,
* one pass through swap_map is enough, but not necessarily:
- * mmput() removes mm from mmlist before exit_mmap() and its
- * zap_page_range(). That's not too bad, those entries are
- * on their way out, and handled faster there than here.
- * do_munmap() behaves similarly, taking the range out of mm's
- * vma list before zap_page_range(). But unfortunately, when
- * unmapping a part of a vma, it takes the whole out first,
- * then reinserts what's left after (might even reschedule if
- * open() method called) - so swap entries may be invisible
- * to swapoff for a while, then reappear - but that is rare.
+ * there are races when an instance of an entry might be missed.
*/
while ((i = find_next_to_unuse(si, i)) != 0) {
if (signal_pending(current)) {
wait_on_page_writeback(page);
/*
- * Remove all references to entry, without blocking.
+ * Remove all references to entry.
* Whenever we reach init_mm, there's no address space
* to search, but use it as a reminder to search shmem.
*/
while (*swap_map > 1 && !retval &&
(p = p->next) != &start_mm->mmlist) {
mm = list_entry(p, struct mm_struct, mmlist);
- atomic_inc(&mm->mm_users);
+ if (atomic_inc_return(&mm->mm_users) == 1) {
+ atomic_dec(&mm->mm_users);
+ continue;
+ }
spin_unlock(&mmlist_lock);
mmput(prev_mm);
prev_mm = mm;
return retval;
}
+/*
+ * After a successful try_to_unuse, if no swap is now in use, we know we
+ * can empty the mmlist. swap_list_lock must be held on entry and exit.
+ * Note that mmlist_lock nests inside swap_list_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 i;
+
+ for (i = 0; i < nr_swapfiles; i++)
+ if (swap_info[i].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 `offset'.
}
down(&swapon_sem);
swap_list_lock();
+ drain_mmlist();
swap_device_lock(p);
swap_file = p->swap_file;
p->swap_file = NULL;
p->highest_bit = 0;
p->cluster_nr = 0;
p->inuse_pages = 0;
- p->sdev_lock = SPIN_LOCK_UNLOCKED;
+ spin_lock_init(&p->sdev_lock);
p->next = -1;
if (swap_flags & SWAP_FLAG_PREFER) {
p->prio =
val->freeswap = nr_swap_pages + nr_to_be_unused;
val->totalswap = total_swap_pages + nr_to_be_unused;
swap_list_unlock();
- if (vx_flags(VXF_VIRT_MEM, 0))
- vx_vsi_swapinfo(val);
+ if (vx_flags(VXF_VIRT_MEM, 0))
+ vx_vsi_swapinfo(val);
}
/*
git://git.onelab.eu / linux-2.6.git / blobdiff