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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 14 Sep 2008 16:12:30 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
Cc:	arjan@...ux.intel.com, tglx@...utronix.de, hpa@...or.com,
	andi@...stfloor.org, linux-kernel@...r.kernel.org,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [patch 1/2] x86: track memtype for RAM in page struct


* Venkatesh Pallipadi <venkatesh.pallipadi@...el.com> wrote:

> From: Suresh Siddha <suresh.b.siddha@...el.com>
> 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/