Re: [PATCH v4 4/4] cma: fix watermark checking

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 24 Sep 2012 11:30:43 +0200
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> wrote:

> On Wednesday 19 September 2012 21:51:02 Andrew Morton wrote:
> > >  
> > >  	/*
> > >  	 * Check whether it is worth even starting compaction. The order check is
> > > @@ -879,6 +880,10 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
> > >  
> > >  	count_vm_event(COMPACTSTALL);
> > >  
> > > +#ifdef CONFIG_CMA
> > > +	if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
> > > +		alloc_flags |= ALLOC_CMA;
> > 
> > I find this rather obscure.  What is the significance of
> > MIGRATE_MOVABLE here?  If it had been 
> > 
> > :	if (allocflags_to_migratetype(gfp_mask) == MIGRATE_CMA)
> > :		alloc_flags |= ALLOC_CMA;
> > 
> > then I'd have read straight past it.  But it's unclear what's happening
> > here.  If we didn't have to resort to telepathy to understand the
> > meaning of ALLOC_CMA, this wouldn't be so hard.

This?

Or am I being more than usually thick?  Is everyone else finding

	if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
		alloc_flags |= ALLOC_CMA;

to be blindingly obvious?


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