linux-kernel - RE: [PATCH] x86, MCE: support memory error recovery for both UCNA and Deferred error in machine_check

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] [day] [month] [year] [list]

Date:	Thu, 23 Oct 2014 17:18:29 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Borislav Petkov <bp@...en8.de>, Chen Yucong <slaoub@...il.com>
CC:	Andi Kleen <ak@...ux.intel.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Aravind Gopalakrishnan <aravind.gopalakrishnan@....com>
Subject: RE: [PATCH] x86, MCE: support memory error recovery for both UCNA
 and Deferred error in machine_check_poll

> The general idea of preemptively poisoning pages which contain deferred
> errors is fine though.

Agreed. I used to think that it wasn't likely to be very useful because in many
cases the UCNA errors are just a trail of breadcrumbs set by different units
on the chip as the poison passed through on the way to consumption - where
there would be a fatal (or recoverable) error.

But recently I found that a partial write to a poisoned cache line only sets the
trail of UCNA errors - there is no consumption, so no machine check.  So in
this case it would definitely be worthwhile to trigger the same action that we
do for SRAO to unmap the page before someone does do a read.

-Tony