[PATCH next/mmotm] swap: add per-partition lock for swapfile fix

Hugh Dickins
2013-01-27T21:47:02Z

I had all cpus spinning in swap_info_get(), for the lock on an area
being swapped off: probably because get_swap_page() forgot to unlock.

Signed-off-by: Hugh Dickins <hughd@google.com>
---

mm/swapfile.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

--- mmotm.orig/mm/swapfile.c 2013-01-23 17:55:39.132447115 -0800
+++ mmotm/mm/swapfile.c 2013-01-27 10:41:45.000000000 -0800
@@ -470,10 +470,9 @@ swp_entry_t get_swap_page(void)
spin_unlock(&swap_lock);
/* This is called for allocating swap entry for cache */
offset = scan_swap_map(si, SWAP_HAS_CACHE);
- if (offset) {
- spin_unlock(&si->lock);
+ spin_unlock(&si->lock);
+ if (offset)
return swp_entry(type, offset);
- }
spin_lock(&swap_lock);
next = swap_list.next;
}