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-rw-r--r--include/linux/swap.h4
-rw-r--r--mm/swapfile.c23
2 files changed, 21 insertions, 6 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index b489bd77bbdc..f02fb5db8914 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -266,6 +266,10 @@ struct swap_info_struct {
* both locks need hold, hold swap_lock
* first.
*/
+ spinlock_t cont_lock; /*
+ * protect swap count continuation page
+ * list.
+ */
struct work_struct discard_work; /* discard worker */
struct swap_cluster_list discard_clusters; /* discard clusters list */
};
diff --git a/mm/swapfile.c b/mm/swapfile.c
index bf91dc9e7a79..e47a21e64764 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2869,6 +2869,7 @@ static struct swap_info_struct *alloc_swap_info(void)
p->flags = SWP_USED;
spin_unlock(&swap_lock);
spin_lock_init(&p->lock);
+ spin_lock_init(&p->cont_lock);
return p;
}
@@ -3545,6 +3546,7 @@ int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
head = vmalloc_to_page(si->swap_map + offset);
offset &= ~PAGE_MASK;
+ spin_lock(&si->cont_lock);
/*
* Page allocation does not initialize the page's lru field,
* but it does always reset its private field.
@@ -3564,7 +3566,7 @@ int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
* a continuation page, free our allocation and use this one.
*/
if (!(count & COUNT_CONTINUED))
- goto out;
+ goto out_unlock_cont;
map = kmap_atomic(list_page) + offset;
count = *map;
@@ -3575,11 +3577,13 @@ int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
* free our allocation and use this one.
*/
if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX)
- goto out;
+ goto out_unlock_cont;
}
list_add_tail(&page->lru, &head->lru);
page = NULL; /* now it's attached, don't free it */
+out_unlock_cont:
+ spin_unlock(&si->cont_lock);
out:
unlock_cluster(ci);
spin_unlock(&si->lock);
@@ -3604,6 +3608,7 @@ static bool swap_count_continued(struct swap_info_struct *si,
struct page *head;
struct page *page;
unsigned char *map;
+ bool ret;
head = vmalloc_to_page(si->swap_map + offset);
if (page_private(head) != SWP_CONTINUED) {
@@ -3611,6 +3616,7 @@ static bool swap_count_continued(struct swap_info_struct *si,
return false; /* need to add count continuation */
}
+ spin_lock(&si->cont_lock);
offset &= ~PAGE_MASK;
page = list_entry(head->lru.next, struct page, lru);
map = kmap_atomic(page) + offset;
@@ -3631,8 +3637,10 @@ static bool swap_count_continued(struct swap_info_struct *si,
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 */
+ if (page == head) {
+ ret = false; /* add count continuation */
+ goto out;
+ }
map = kmap_atomic(page) + offset;
init_map: *map = 0; /* we didn't zero the page */
}
@@ -3645,7 +3653,7 @@ init_map: *map = 0; /* we didn't zero the page */
kunmap_atomic(map);
page = list_entry(page->lru.prev, struct page, lru);
}
- return true; /* incremented */
+ ret = true; /* incremented */
} else { /* decrementing */
/*
@@ -3671,8 +3679,11 @@ init_map: *map = 0; /* we didn't zero the page */
kunmap_atomic(map);
page = list_entry(page->lru.prev, struct page, lru);
}
- return count == COUNT_CONTINUED;
+ ret = count == COUNT_CONTINUED;
}
+out:
+ spin_unlock(&si->cont_lock);
+ return ret;
}
/*