[uml-devel] Re: GFP_ATOMIC/GFP_KERNEL broken for use by block devices!!

[Blaisorblade <blaisorblade@yahoo.it>]

On Tuesday 25 October 2005 01:03, Jeff Dike wrote:
> On Sat, Oct 22, 2005 at 06:38:16PM +0200, Blaisorblade wrote:
> > In the write path of a ???lesystem, using
> > GFP_KERNEL or GFP_ATOMIC will lead to deadlocks
> > eventually. [...] GFP_NOFS is there for a reason, as is GFP_NOIO for
> > block device drivers.
>
> I know about this, and this is another reason I'm not sending it in.
I didn't know and you didn't mention, so I thought I'd better add about this.
> I 
> don't really understand it either.

> If GFP_ATOMIC can block, then I don't 
> know what good it is.
I _don't_ think it can block. I understand why GFP_KERNEL is broken there, but 
not why GFP_ATOMIC can't be used. The only pointer I found so far is that 
__GFP_HIGH allows the kernel to use up more memory without doing reclaim (see 
mm/page_alloc.c, calls to zone_watermark_ok).
> > Which means that we _must_ ask for help from somebody else.
>
> Yup.
>
> 				Jeff

-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

	

	
		
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