From 752dc185dacba1edcba425e67fc6df3c7793a5c3 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Sat, 2 Jun 2012 00:27:47 -0700 Subject: [PATCH] mm: fix warning in __set_page_dirty_nobuffers New tmpfs use of !PageUptodate pages for fallocate() is triggering the WARNING: at mm/page-writeback.c:1990 when __set_page_dirty_nobuffers() is called from migrate_page_copy() for compaction. It is anomalous that migration should use __set_page_dirty_nobuffers() on an address_space that does not participate in dirty and writeback accounting; and this has also been observed to insert surprising dirty tags into a tmpfs radix_tree, despite tmpfs not using tags at all. We should probably give migrate_page_copy() a better way to preserve the tag and migrate accounting info, when mapping_cap_account_dirty(). But that needs some more work: so in the interim, avoid the warning by using a simple SetPageDirty on PageSwapBacked pages. Reported-and-tested-by: Dave Jones Signed-off-by: Hugh Dickins Signed-off-by: Linus Torvalds --- mm/migrate.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index ab81d482ae6f..be26d5cbe56b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -436,7 +436,10 @@ void migrate_page_copy(struct page *newpage, struct page *page) * is actually a signal that all of the page has become dirty. * Whereas only part of our page may be dirty. */ - __set_page_dirty_nobuffers(newpage); + if (PageSwapBacked(page)) + SetPageDirty(newpage); + else + __set_page_dirty_nobuffers(newpage); } mlock_migrate_page(newpage, page); -- 2.20.1