[PATCH 04/26] xfs: Improve metadata buffer reclaim accountability

Dave Chinner
2019-10-09T03:21:35Z

From: Dave Chinner <dchinner@redhat.com>

The buffer cache shrinker frees more than just the xfs_buf slab
objects - it also frees the pages attached to the buffers. Make sure
the memory reclaim code accounts for this memory being freed
correctly, similar to how the inode shrinker accounts for pages
freed from the page cache due to mapping invalidation.

We also need to make sure that the mm subsystem knows these are
reclaimable objects. We provide the memory reclaim subsystem with a
a shrinker to reclaim xfs_bufs, so we should really mark the slab
that way.

We also have a lot of xfs_bufs in a busy system, spread them around
like we do inodes.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_buf.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index e484f6bead53..45b470f55ad7 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -324,6 +324,9 @@ xfs_buf_free(

__free_page(page);
}
+ if (current->reclaim_state)
+ current->reclaim_state->reclaimed_slab +=
+ bp->b_page_count;
} else if (bp->b_flags & _XBF_KMEM)
kmem_free(bp->b_addr);
_xfs_buf_free_pages(bp);
@@ -2064,7 +2067,8 @@ int __init
xfs_buf_init(void)
{
xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
- KM_ZONE_HWALIGN, NULL);
+ KM_ZONE_HWALIGN | KM_ZONE_SPREAD | KM_ZONE_RECLAIM,
+ NULL);
if (!xfs_buf_zone)
goto out;

--
2.23.0.rc1