When, read_tree_block() returns error it has already freed the extent_buffer
read_tree_block(..)
{
::
ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid); <==
fails
if (ret) {
free_extent_buffer(buf); <=== its freed already
return ERR_PTR(ret);
}
::
}
open_ctree()
{
::
chunk_root->node = read_tree_block(..);
::
BTRFS: failed to read chunk root on sdf
BUG: unable to handle kernel NULL pointer dereference at 000000000000001f
IP: [<ffffffffa04f930e>] free_extent_buffer+0x1e/0xb0 [btrfs]
::
[<ffffffffa04c7dae>] ? free_root_extent_buffers+0x1e/0x40 [btrfs]
[<ffffffffa04c7e26>] free_root_pointers+0x56/0x60 [btrfs]
[<ffffffffa04cebc0>] open_ctree+0x19e0/0x2360 [btrfs]
[<ffffffffa04a2676>] btrfs_mount+0x9e6/0xb10 [btrfs]
[<ffffffff81353cea>] ? find_next_zero_bit+0x1a/0x30
[<ffffffff81353cb5>] ? find_next_bit+0x15/0x30
[<ffffffff8119246a>] ? pcpu_alloc+0x35a/0x680
[<ffffffff811ec648>] mount_fs+0x38/0x190
[<ffffffff811927c5>] ? __alloc_percpu+0x15/0x20
[<ffffffff81207ecb>] vfs_kern_mount+0x6b/0x120
[<ffffffffa04a1e88>] btrfs_mount+0x1f8/0xb10 [btrfs]
[<ffffffff8119246a>] ? pcpu_alloc+0x35a/0x680
[<ffffffff811ec648>] mount_fs+0x38/0x190
[<ffffffff811927c5>] ? __alloc_percpu+0x15/0x20
[<ffffffff81207ecb>] vfs_kern_mount+0x6b/0x120
[<ffffffff8120af54>] do_mount+0x224/0xb80
[<ffffffff8120bbbe>] SyS_mount+0x7e/0xe0
[<ffffffff815d00ae>] system_call_fastpath+0x12/0x71
this patch avoids calling it again
Signed-off-by: Anand Jain <anand.j...@oracle.com>
---
fs/btrfs/disk-io.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index da7b7bf..e8901ac 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2081,7 +2081,8 @@ static void btrfs_stop_all_workers(struct btrfs_fs_info
*fs_info)
static void free_root_extent_buffers(struct btrfs_root *root)
{
if (root) {
- free_extent_buffer(root->node);
+ if (!IS_ERR(root->node))
+ free_extent_buffer(root->node);
free_extent_buffer(root->commit_root);
root->node = NULL;
root->commit_root = NULL;
--
2.4.1
--
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