Re: [Scst-devel] strane kernel BUG

[Bart V. A. <bva...@ac...>]

On 10/13/14 22:12, Matteo Tescione wrote:
> Path: scst-trunk
> URL: svn://svn.code.sf.net/p/scst/svn/trunk
> Repository Root: svn://svn.code.sf.net/p/scst/svn
> Repository UUID: d57e44dd-8a1f-0410-8b47-8ef2f437770f
> Revision: 5704
>
> drbd version: 8.4.4 (api:1/proto:86-101) from standard package,
 > running kernel 3.12.14 patched with scst_exec_req_fifo and
 > put_page_callback applied.

Hello Matteo,

To me this looks like a DRBD bug. If a timeout of a DRBD request occurs 
the DRBD timeout handler (request_timer_fn()) is called, that function 
grabs a spinlock and next calls kthread_create_on_node() with that 
spinlock held. kthread_create_on_node() can sleep which means that it is 
not allowed to call that function with a spinlock held. I'm not sure why 
this particular behavior has not yet been noticed before. Can you post 
the first call stack from the e-mail at the start of this thread 
together with the kernel version number on a DRBD-related mailing list 
and ask the DRBD authors for their opinion ?

Thanks,

Bart.