From: Hugh Dickins If a regular swapfile lies on a filesystem whose blocksize is less than PAGE_SIZE, then setup_swap_extents may have to cut the number of usable swap pages; but sys_swapon's nr_good_pages was not expecting that. Also, setup_swap_extents takes no account of badpages listed in the swap header: not worth doing so, but ensure nr_badpages is 0 for a regular swapfile. Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton --- mm/swapfile.c | 25 ++++++++++++++++--------- 1 files changed, 16 insertions(+), 9 deletions(-) diff -puN mm/swapfile.c~swap-correct-swapfile-nr_good_pages mm/swapfile.c --- devel/mm/swapfile.c~swap-correct-swapfile-nr_good_pages 2005-07-08 22:34:39.000000000 -0700 +++ devel-akpm/mm/swapfile.c 2005-07-08 22:34:39.000000000 -0700 @@ -1008,8 +1008,9 @@ reprobe: } ret = 0; if (page_no == 0) - ret = -EINVAL; + page_no = 1; /* force Empty message */ sis->max = page_no; + sis->pages = page_no - 1; sis->highest_bit = page_no - 1; done: sis->curr_swap_extent = list_entry(sis->extent_list.prev, @@ -1446,6 +1447,10 @@ asmlinkage long sys_swapon(const char __ p->highest_bit = maxpages - 1; error = -EINVAL; + if (!maxpages) + goto bad_swap; + if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) + goto bad_swap; if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) goto bad_swap; @@ -1470,25 +1475,27 @@ asmlinkage long sys_swapon(const char __ if (error) goto bad_swap; } - + if (swapfilesize && maxpages > swapfilesize) { printk(KERN_WARNING "Swap area shorter than signature indicates\n"); error = -EINVAL; goto bad_swap; } + if (nr_good_pages) { + p->swap_map[0] = SWAP_MAP_BAD; + p->max = maxpages; + p->pages = nr_good_pages; + error = setup_swap_extents(p); + if (error) + goto bad_swap; + nr_good_pages = p->pages; + } if (!nr_good_pages) { printk(KERN_WARNING "Empty swap-file\n"); error = -EINVAL; goto bad_swap; } - p->swap_map[0] = SWAP_MAP_BAD; - p->max = maxpages; - p->pages = nr_good_pages; - - error = setup_swap_extents(p); - if (error) - goto bad_swap; down(&swapon_sem); swap_list_lock(); _