Re: [BUG REPORT] Kernel panic on 3.9.0-rc7-4-gbb33db7

Jens Axboe
2013-04-19T13:33:22Z

On Thu, Apr 18 2013, Tejun Heo wrote:
> (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?

Ugh, wtf.

Chris, time for a swim in the bay :-)

--
Jens Axboe