Re: NILFS2 get stuck after bio_alloc() fail

[Alberto Bertogli <albertito@blitiri.com.ar>]

On Sat, Jun 13, 2009 at 10:32:11PM -0300, Leandro Lucarella wrote:
> Hi!
> 
> While testing nilfs2 (using 2.6.30) doing some "cp"s and "rm"s, I noticed
> sometimes they got stucked in D state, and the kernel had said the
> following message:
> 
>         NILFS: IO error writing segment
> 
> A friend gave me a hand and after adding some printk()s we found out that
> the problem seems to occur when bio_alloc()s inside nilfs_alloc_seg_bio()
> fail, making it return NULL; but we don't know how that causes the
> processes to get stucked.

By the way, those bio_alloc()s are using GFP_NOWAIT but it looks like they
could use at least GFP_NOIO or GFP_NOFS, since the caller can (and sometimes
do) sleep. The only caller is nilfs_submit_bh(), which calls
nilfs_submit_seg_bio() which can sleep calling wait_for_completion(). Is there
something I'm missing?

Thanks a lot,
		Alberto