Re: 2.5.49: kernel BUG at drivers/block/ll_rw_blk.c:1950!

[Andrew Morton]

Srihari Vijayaraghavan wrote:
> 
> [1.] One line summary of the problem:
> kernel BUG at drivers/block/ll_rw_blk.c:1950!

That's BIO_BUG_ON(!bio->bi_size);

> Software RAID 0.

Yes, there have been a few reports of this.  The pagecache code
does bio_add_page() against a new BIO and it doesn't work.  We
end up submitting an empty BIO and boom.

I've seen various RAID patches floating about which address this,
but either they weren't merged or they didn't work right.

Jens, what is the policy here?  Should bio_add_page() for an
empty bio "always succeed"?  (Bearing in mind that pages can
be 64k...).    I guess -EIO would be better than a BUG.

Are there more RAID fixes pending?

Thanks.