Re: [patch 1/2] x86: track memtype for RAM in page struct

* Venkatesh Pallipadi [off-list ref] wrote:

From: Suresh Siddha <redacted>
Subject: [patch 1/2] x86: track memtype for RAM in page struct

Track the memtype for RAM pages in page struct instead of using the 
memtype list. This avoids the explosion in the number of entries in 
memtype list (of the order of 20,000 with AGP) and makes the PAT 
tracking simpler. We are using PG_arch_1 bit in page->flags.

this is in contradiction to this comment:

 /*
+ * RED-PEN:  TODO: Add PageReserved() check aswell here,
+ * once we add SetPageReserved() to all the drivers using
+ * set_memory_* or set_pages_*

if it's marked PG_arch_1, why is there any need for PageReserved?

+ *
+ * This will help prevent accidentally freeing pages
+ * before setting the attribute back to WB.

setting it PageReserved is a hack. We should set it PG_arch_1 and extend 
the page allocator to emit a kernel warning if a PG_arch_1 page is 
freed.

	Ingo