Re: kernel 3.17-rc3: task rsync:2524 blocked for more than 120 seconds

[Chris Mason <clm@fb.com>]

> On 09/02/2014 03:56 PM, john terragon wrote:
> Nice...now I get the hung task even with 3.14.17.... And I tried with
> 4K for node and leaf size...same result. And to top it all off, today
> I've been bitten by the bug also on my main root fs (which is on two
> fast ssd), although with 3.16.1.
> 
> Is it at least safe for the data? I mean, as long as the hung process
> terminates and no other error shows up, can I at least be sure that
> the data written is correct?

Your traces are a little different.  The ENOSPC code is throttling
things to make sure you have enough room for the writes you're doing.
The code we have in 3.17-rc3 (or my for-linus branch) are the best
choices right now.  You can pull that down to 3.16 if you want all the
fixes on a more stable kernel.

Nailing down the ENOSPC code is going to be a little different, I think
autodefrag probably isn't interacting well with being short on space and
encryption.  This is leading to much more IO than we'd normally do, and
dm-crypt makes it fairly intensive.

Can you try flipping off autodefrag?

-chris