[PATCH 4.5 098/101] btrfs: fallback to vmalloc in btrfs_compare_tree

Greg Kroah-Hartman
2016-05-17T01:29:28Z

From: David Sterba <dsterba@suse.com>

commit 8f282f71eaee7ac979cdbe525f76daa0722798a8 upstream.

The allocation of node could fail if the memory is too fragmented for a
given node size, practically observed with 64k.

http://article.gmane.org/gmane.comp.file-systems.btrfs/54689

Reported-and-tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/btrfs/ctree.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -19,6 +19,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/rbtree.h>
+#include <linux/vmalloc.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
@@ -5361,10 +5362,13 @@ int btrfs_compare_trees(struct btrfs_roo
goto out;
}

- tmp_buf = kmalloc(left_root->nodesize, GFP_NOFS);
+ tmp_buf = kmalloc(left_root->nodesize, GFP_KERNEL | __GFP_NOWARN);
if (!tmp_buf) {
- ret = -ENOMEM;
- goto out;
+ tmp_buf = vmalloc(left_root->nodesize);
+ if (!tmp_buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
}

left_path->search_commit_root = 1;
@@ -5565,7 +5569,7 @@ int btrfs_compare_trees(struct btrfs_roo
out:
btrfs_free_path(left_path);
btrfs_free_path(right_path);
- kfree(tmp_buf);
+ kvfree(tmp_buf);
return ret;
}