From 3a902c5f6851cd0b64c33efaa3bd57aa27a82efb Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 30 Apr 2008 00:55:16 -0700 Subject: [PATCH] mm: fix warning on memory offline KAMEZAWA Hiroyuki found a warning message in the buffer dirtying code that is coming from page migration caller. WARNING: at fs/buffer.c:720 __set_page_dirty+0x330/0x360() Call Trace: [] show_stack+0x80/0xa0 [] dump_stack+0x30/0x60 [] warn_on_slowpath+0x90/0xe0 [] __set_page_dirty+0x330/0x360 [] __set_page_dirty_buffers+0xd0/0x280 [] set_page_dirty+0xc0/0x260 [] migrate_page_copy+0x5d0/0x5e0 [] buffer_migrate_page+0x2e0/0x3c0 [] migrate_pages+0x770/0xe00 What was happening is that migrate_page_copy wants to transfer the PG_dirty bit from old page to new page, so what it would do is set_page_dirty(newpage). However set_page_dirty() is used to set the entire page dirty, wheras in this case, only part of the page was dirty, and it also was not uptodate. Marking the whole page dirty with set_page_dirty would lead to corruption or unresolvable conditions -- a dirty && !uptodate page and dirty && !uptodate buffers. Possibly we could just ClearPageDirty(oldpage); SetPageDirty(newpage); however in the interests of keeping the change minimal... Signed-off-by: Nick Piggin Tested-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/migrate.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index 4e0eccca5e..449d77d409 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -383,7 +383,14 @@ static void migrate_page_copy(struct page *newpage, struct page *page) if (PageDirty(page)) { clear_page_dirty_for_io(page); - set_page_dirty(newpage); + /* + * Want to mark the page and the radix tree as dirty, and + * redo the accounting that clear_page_dirty_for_io undid, + * but we can't use set_page_dirty because that function + * is actually a signal that all of the page has become dirty. + * Wheras only part of our page may be dirty. + */ + __set_page_dirty_nobuffers(newpage); } #ifdef CONFIG_SWAP -- 2.39.5