[dm-devel] [BUG REPORT] Kernel panic on 3.9.0-rc7-4-gbb33db7

[Tejun Heo]

(cc'ing btrfs people)

On Fri, Apr 19, 2013 at 11:33:20AM +0800, Wanlong Gao wrote:
> RIP: 0010:[<ffffffff812484d3>]  [<ffffffff812484d3>] ftrace_raw_event_block_bio_complete+0x73/0xf0
...
>  [<ffffffff811b6c10>] bio_endio+0x80/0x90
>  [<ffffffffa0790d26>] btrfs_end_bio+0xf6/0x190 [btrfs]
>  [<ffffffff811b6bcd>] bio_endio+0x3d/0x90
>  [<ffffffff81249873>] req_bio_endio+0xa3/0xe0

Ugh....

In fs/btrfs/volumes.c

  static void bbio_error(struct btrfs_bio *bbio, struct bio *bio, u64 logical)
  {
	...
		bio->bi_bdev = (struct block_device *)
			       	       (unsigned long)bbio->mirror_num;
	...
  }

  static void btrfs_end_bio(struct bio *bio, int err)
  {
	...
		bio->bi_bdev = (struct block_device *)
					(unsigned long)bbio->mirror_num;
									
	...
  }

In fs/btrfs/extent_io.c

  static void end_bio_extent_readpage(struct bio *bio, int err)
  {
	int mirror;
	...
		mirror = (int)(unsigned long)bio->bi_bdev;
	...
  }

Ewweeeeeeeeeeeeeeeeeehh........

No wonder this thing crashes.  Chris, can't the original bio carry
bbio in bi_private and let end_bio_extent_readpage() free the bbio
instead of abusing bi_bdev like this?

-- 
tejun