Re: PF_MEMALLOC in 2.6

Oliver Neukum
2004-08-20T15:33:20Z

Am Freitag, 20. August 2004 12:31 schrieb Stephen C. Tweedie:
> Hi,
>
> On Thu, 2004-08-19 at 13:41, Hugh Dickins wrote:
>
> > Or would it solve the problem at hand, if it made itself PF_MEMALLOC
> > just while servicing a request from a PF_MEMALLOC?
>
> It's not the PF_* state of the caller who submitted the IO that matters,
> though --- it's the state of all threads _waiting_ on the IO, which may
> be different, and which can change even after the IO has begun.
>
> Eg. kswapd does a writepage, the writepage needs to allocate disk space,
> and in doing so tries to access a metadata block which is already
> undergoing IO from a different thread altogether.

Then how do the current SCSI drivers work?

Regards
Oliver