[PATCH 089/102] xfs: fix memory reclaim deadlock on agi buffer

Dave Chinner
2012-08-23T05:05:09Z

From: Peter Watkins <treestem@gmail.com>

Upstream commit: 3ba316037470bbf98c8a16c2179c02794fb8862e

Note xfs_iget can be called while holding a locked agi buffer. If
it goes into memory reclaim then inode teardown may try to lock the
same buffer. Prevent the deadlock by calling radix_tree_preload
with GFP_NOFS.

Signed-off-by: Peter Watkins <treestem@gmail.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
---
fs/xfs/xfs_iget.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
index 35b1f7b..a3663a8 100644
--- a/fs/xfs/xfs_iget.c
+++ b/fs/xfs/xfs_iget.c
@@ -337,9 +337,10 @@ xfs_iget_cache_miss(
/*
* Preload the radix tree so we can insert safely under the
* write spinlock. Note that we cannot sleep inside the preload
- * region.
+ * region. Since we can be called from transaction context, don't
+ * recurse into the file system.
*/
- if (radix_tree_preload(GFP_KERNEL)) {
+ if (radix_tree_preload(GFP_NOFS)) {
error = EAGAIN;
goto out_destroy;