Hello, This patch try to solve problem that a long-lasting page cache of ext4 superblock disturbs page migration.
I've been testing CMA feature on my ARM-based platform and found some pages for page caches cannot be migrated. Some of them are page caches of superblock of ext4 filesystem. Current ext4 reads superblock with sb_bread(). sb_bread() allocates page from movable area. But the problem is that ext4 hold the page until it is unmounted. If root filesystem is ext4 the page cannot be migrated forever. I introduce a new API for allocating page from non-movable area. It is useful for ext4 and others that want to hold page cache for a long time. I have 2 patchs: 1. Patch 1/2: introduce a new API that create page cache from non-movable area 2. Patch 2/2: have ext4 use the new API to read superblock This patchset is based on linux-next-20140717. Thanks a lot. Gioh Kim (2): fs/buffer.c: allocate buffer cache from non-movable area ext4: allocate buffer-cache for superblock in non-movable area fs/buffer.c | 39 ++++++++++++++++++++++++++++++++------- fs/ext4/super.c | 6 +++--- include/linux/buffer_head.h | 8 ++++++++ 3 files changed, 43 insertions(+), 10 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
