Re: problem with nilfs_cleanerd

[Ryusuke Konishi <ryusuke-sG5X7nlA6pw@public.gmane.org>]

Hi,

On Tue, 06 Jul 2010 11:02:41 +0200, Łukasz_Wójcicki wrote:
> I'am using kernel 2.6.20 with nilf_utils-2-0-18 and nilfs kernel module
> 2-0-20 .
> 
> <1>Unable to handle kernel NULL pointer dereference at virtual address
> 00000000
> <1>pgd = c4eb0000
> <1>[00000000] *pgd=c4e2d031, *pte=00000000, *ppte=00000000
> <4>Internal error: Oops: 17 [#1]
> <4>Modules linked in:
> <4>CPU: 0
> <4>PC is at nilfs_btree_lookup_dirty_buffers+0x10c/0x1ec
> <4>LR is at 0xc4c99b24
<snip>

Could you try the following patch to narrow down the cause?

There is a function lacking range check in the btree code.  This patch
will catch the defect if the oops comes from a range error.

I'm now reviewing the btree code to find out root cause of the range
error.

Thanks,
Ryusuke Konishi
---

diff --git a/fs/btree.c b/fs/btree.c
index beb11fe..9622ff4 100644
--- a/fs/btree.c
+++ b/fs/btree.c
@@ -2007,6 +2007,15 @@ static void nilfs_btree_add_dirty_buffer(struct nilfs_btree *btree,
 	node = (struct nilfs_btree_node *)bh->b_data;
 	key = nilfs_btree_node_get_key(node, 0);
 	level = nilfs_btree_node_get_level(node);
+	if (level < NILFS_BTREE_LEVEL_NODE_MIN ||
+	    level >= NILFS_BTREE_LEVEL_MAX) {
+		dump_stack();
+		printk(KERN_CRIT
+		       "%s: invalid btree level: %d (ino=%lu)\n", __func__,
+		       level, NILFS_BMAP_I(&btree->bt_bmap)->vfs_inode.i_ino);
+		return;
+	}
+
 	list_for_each(head, &lists[level]) {
 		cbh = list_entry(head, struct buffer_head, b_assoc_buffers);
 		cnode = (struct nilfs_btree_node *)cbh->b_data;
-- 
1.6.6.2