From aaa468653b4a0d11c603c48d716f765177a5a9e4 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 14 Dec 2009 17:58:47 -0800 Subject: swap_info: note SWAP_MAP_SHMEM While we're fiddling with the swap_map values, let's assign a particular value to shmem/tmpfs swap pages: their swap counts are never incremented, and it helps swapoff's try_to_unuse() a little if it can immediately distinguish those pages from process pages. Since we've no use for SWAP_MAP_BAD | COUNT_CONTINUED, we might as well use that 0xbf value for SWAP_MAP_SHMEM. Signed-off-by: Hugh Dickins Reviewed-by: KAMEZAWA Hiroyuki Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/shmem.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'mm/shmem.c') diff --git a/mm/shmem.c b/mm/shmem.c index 356dd99566e..4fb41c83dac 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1017,7 +1017,14 @@ int shmem_unuse(swp_entry_t entry, struct page *page) goto out; } mutex_unlock(&shmem_swaplist_mutex); -out: return found; /* 0 or 1 or -ENOMEM */ + /* + * Can some race bring us here? We've been holding page lock, + * so I think not; but would rather try again later than BUG() + */ + unlock_page(page); + page_cache_release(page); +out: + return (found < 0) ? found : 0; } /* @@ -1080,7 +1087,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) else inode = NULL; spin_unlock(&info->lock); - swap_duplicate(swap); + swap_shmem_alloc(swap); BUG_ON(page_mapped(page)); page_cache_release(page); /* pagecache ref */ swap_writepage(page, wbc); -- cgit v1.2.3