Re: [PATCH] Permit inode & dentry hash tables to be allocated >MAX_ORDER size

[Andrew Morton]

"Martin J. Bligh" <mbligh@xxxxxxxxxxx> wrote:
>
> --On Friday, June 11, 2004 16:19:20 -0700 Andrew Morton <akpm@xxxxxxxx> wrote:
> 
> > "Martin J. Bligh" <mbligh@xxxxxxxxxxx> wrote:
> >> 
> >> We've hit a problem with alignment issues where the start of the zone is
> >> aligned to 16MB, for instance, and the max grouping is now 256MB. That
> >> generatates a "warning: wrong zone alignment: it will crash" error (or
> >> something similar). Andy sent me a patch this morning to throw away
> >> the lower section, which is much nicer than crashing ... but I'd prefer
> >> not to throw that RAM away unless we have to. 
> > 
> > Confused.  Why do we have that test in there at all?  We should just toss
> > the pages one at a time into the buddy list and let the normal coalescing
> > work it out.  That way we'd end up with a single 16MB "page" followed by N
> > 256MB "pages".
> 
> That's what I thought ... Andy looked at it more than I did, but I think
> he's asleep, unfortunately. IIRC, he said the buddy stuff keys off 
> zone_start_pfn though. Maybe that's fixable ...

Doesn't look that way.  It uses

	(zone->zone_mem_map - page) >> (1 + order)

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