From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 20 Nov 2008 01:20:09 +0000 (GMT) From: Hugh Dickins Subject: [PATCH 5/7] mm: replace some BUG_ONs by VM_BUG_ONs In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Nick Piggin , Christoph Lameter , KAMEZAWA Hiroyuki , linux-mm@kvack.org List-ID: The swap code is over-provisioned with BUG_ONs on assorted page flags, mostly dating back to 2.3. They're good documentation, and guard against developer error, but a waste of space on most systems: change them to VM_BUG_ONs, conditional on CONFIG_DEBUG_VM. Just delete the PagePrivate ones: they're later, from 2.5.69, but even less interesting now. Signed-off-by: Hugh Dickins --- Could be taken further: this now looks like a random selection which caught my eye at some point working in these files. This patch clashes trivially in __delete_from_swap_cache with memcg-memswap-controller-core.patch, which I'm assuming comes later: sorry, but you'll have no difficulty in fixing it up. mm/page_io.c | 4 ++-- mm/swap_state.c | 19 +++++++++---------- mm/swapfile.c | 8 +++----- 3 files changed, 14 insertions(+), 17 deletions(-) --- mmclean4/mm/page_io.c 2008-04-17 03:49:44.000000000 +0100 +++ mmclean5/mm/page_io.c 2008-11-19 15:26:26.000000000 +0000 @@ -125,8 +125,8 @@ int swap_readpage(struct file *file, str struct bio *bio; int ret = 0; - BUG_ON(!PageLocked(page)); - BUG_ON(PageUptodate(page)); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(PageUptodate(page)); bio = get_swap_bio(GFP_KERNEL, page_private(page), page, end_swap_bio_read); if (bio == NULL) { --- mmclean4/mm/swap_state.c 2008-10-24 09:28:26.000000000 +0100 +++ mmclean5/mm/swap_state.c 2008-11-19 15:26:26.000000000 +0000 @@ -72,10 +72,10 @@ int add_to_swap_cache(struct page *page, { int error; - BUG_ON(!PageLocked(page)); - BUG_ON(PageSwapCache(page)); - BUG_ON(PagePrivate(page)); - BUG_ON(!PageSwapBacked(page)); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(PageSwapCache(page)); + VM_BUG_ON(!PageSwapBacked(page)); + error = radix_tree_preload(gfp_mask); if (!error) { page_cache_get(page); @@ -108,10 +108,9 @@ int add_to_swap_cache(struct page *page, */ void __delete_from_swap_cache(struct page *page) { - BUG_ON(!PageLocked(page)); - BUG_ON(!PageSwapCache(page)); - BUG_ON(PageWriteback(page)); - BUG_ON(PagePrivate(page)); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(!PageSwapCache(page)); + VM_BUG_ON(PageWriteback(page)); radix_tree_delete(&swapper_space.page_tree, page_private(page)); set_page_private(page, 0); @@ -134,8 +133,8 @@ int add_to_swap(struct page * page, gfp_ swp_entry_t entry; int err; - BUG_ON(!PageLocked(page)); - BUG_ON(!PageUptodate(page)); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(!PageUptodate(page)); for (;;) { entry = get_swap_page(); --- mmclean4/mm/swapfile.c 2008-10-24 09:28:26.000000000 +0100 +++ mmclean5/mm/swapfile.c 2008-11-19 15:26:26.000000000 +0000 @@ -333,7 +333,7 @@ int can_share_swap_page(struct page *pag { int count; - BUG_ON(!PageLocked(page)); + VM_BUG_ON(!PageLocked(page)); count = page_mapcount(page); if (count <= 1 && PageSwapCache(page)) count += page_swapcount(page); @@ -350,8 +350,7 @@ static int remove_exclusive_swap_page_co struct swap_info_struct * p; swp_entry_t entry; - BUG_ON(PagePrivate(page)); - BUG_ON(!PageLocked(page)); + VM_BUG_ON(!PageLocked(page)); if (!PageSwapCache(page)) return 0; @@ -432,7 +431,6 @@ void free_swap_and_cache(swp_entry_t ent if (page) { int one_user; - BUG_ON(PagePrivate(page)); one_user = (page_count(page) == 2); /* Only cache user (+us), or swap space full? Free it! */ /* Also recheck PageSwapCache after page is locked (above) */ @@ -1209,7 +1207,7 @@ int page_queue_congested(struct page *pa { struct backing_dev_info *bdi; - BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */ + VM_BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */ if (PageSwapCache(page)) { swp_entry_t entry = { .val = page_private(page) }; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org