From 7db7671f835ccad66db20154ac1274140937d9b7 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 5 Nov 2015 18:49:49 -0800 Subject: mm: page migration trylock newpage at same level as oldpage Clean up page migration a little by moving the trylock of newpage from move_to_new_page() into __unmap_and_move(), where the old page has been locked. Adjust unmap_and_move_huge_page() and balloon_page_migrate() accordingly. But make one kind-of-functional change on the way: whereas trylock of newpage used to BUG() if it failed, now simply return -EAGAIN if so. Cutting out BUG()s is good, right? But, to be honest, this is really to extend the usefulness of the custom put_new_page feature, allowing a pool of new pages to be shared perhaps with racing uses. Use an "else" instead of that "skip_unmap" label. Signed-off-by: Hugh Dickins Cc: Christoph Lameter Cc: "Kirill A. Shutemov" Cc: Rik van Riel Cc: Vlastimil Babka Cc: Davidlohr Bueso Cc: Oleg Nesterov Cc: Sasha Levin Cc: Dmitry Vyukov Cc: KOSAKI Motohiro Acked-by: Rafael Aquini Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/balloon_compaction.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) (limited to 'mm/balloon_compaction.c') diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c index fcad8322ef36..d3116be5a00f 100644 --- a/mm/balloon_compaction.c +++ b/mm/balloon_compaction.c @@ -199,23 +199,17 @@ int balloon_page_migrate(struct page *newpage, struct balloon_dev_info *balloon = balloon_page_device(page); int rc = -EAGAIN; - /* - * Block others from accessing the 'newpage' when we get around to - * establishing additional references. We should be the only one - * holding a reference to the 'newpage' at this point. - */ - BUG_ON(!trylock_page(newpage)); + VM_BUG_ON_PAGE(!PageLocked(page), page); + VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); if (WARN_ON(!__is_movable_balloon_page(page))) { dump_page(page, "not movable balloon page"); - unlock_page(newpage); return rc; } if (balloon && balloon->migratepage) rc = balloon->migratepage(balloon, newpage, page, mode); - unlock_page(newpage); return rc; } #endif /* CONFIG_BALLOON_COMPACTION */ -- cgit v1.2.3