From 88dbcbb3a4847f5e6dfeae952d3105497700c128 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Fri, 28 Dec 2018 00:39:16 -0800 Subject: blkdev: avoid migration stalls for blkdev pages Currently, block device pages don't provide a ->migratepage callback and thus fallback_migrate_page() is used for them. This handler cannot deal with dirty pages in async mode and also with the case a buffer head is in the LRU buffer head cache (as it has elevated b_count). Thus such page can block memory offlining. Fix the problem by using buffer_migrate_page_norefs() for migrating block device pages. That function takes care of dropping bh LRU in case migration would fail due to elevated buffer refcount to avoid stalls and can also migrate dirty pages without writing them. Link: http://lkml.kernel.org/r/20181211172143.7358-6-jack@suse.cz Signed-off-by: Jan Kara Acked-by: Mel Gorman Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/block_dev.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/block_dev.c b/fs/block_dev.c index a80b4f0ee7c4f1..de2135178e621a 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1966,6 +1966,7 @@ static const struct address_space_operations def_blk_aops = { .writepages = blkdev_writepages, .releasepage = blkdev_releasepage, .direct_IO = blkdev_direct_IO, + .migratepage = buffer_migrate_page_norefs, .is_dirty_writeback = buffer_check_dirty_writeback, }; -- cgit 1.2.3-korg