[DRBD-user] drbd 7 + xfs + 2.6.7

Lars Marowsky-Bree lmb at suse.de
Fri Jul 23 01:17:14 CEST 2004

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On 2004-07-22T22:15:34,
   Lars Ellenberg <Lars.Ellenberg at linbit.com> said:

>   or: xfs for some reason kmem_zone_free's (kmem_cache_free) the
>   submitted pages _before_ they are sent (so before io on that page has
>   completed. no bio_endio called yet!). which means that xfs "frees" a
>   page of which the tcp stack still holds a reference.
>     this seem to be the likely code path.
>     now. either no one except xfs may hold a reference to their pages.
>     then xfs should prominently state this somewhere.
>     or xfs just does something it must not do: freeing pages that have
>     reference counts.
> 
>   someone wants to ask the xfs guys about this?

Just drop them an e-mail ;-)

> solution approaches:
>   a. we could disable zero copy networking completely (tcp_sendpage).
>   b. we could make it configurable.
>   c. we could simply fall back to tcp_sendmsg for slab pages.
> 
> patch for c. is attached.  if it works for Florin (please confirm),
> then it will go into svn soonish.

Sounds OK, what's the performance impact here? Does this affect anything
but !&@#&#(! XFS?


Sincerely,
    Lars Marowsky-Brée <lmb at suse.de>

-- 
High Availability & Clustering	    \ ever tried. ever failed. no matter.
SUSE Labs, Research and Development | try again. fail again. fail better.
SUSE LINUX AG - A Novell company    \ 	-- Samuel Beckett




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