linux-kernel - Re: [concept & "good taste" review] persistent store

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 for Android: free password hash cracker in your pocket

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

Message-ID: <1292609952.2820.43.camel@mulgrave.site>
Date:	Fri, 17 Dec 2010 13:19:12 -0500
From:	James Bottomley <James.Bottomley@...senPartnership.com>
To:	Tony Luck <tony.luck@...el.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
	tglx@...utronix.de, mingo@...e.hu, greg@...ah.com,
	akpm@...ux-foundation.org, ying.huang@...el.com,
	Borislav Petkov <bp@...en8.de>,
	David Miller <davem@...emloft.net>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Kyungmin Park <kmpark@...radead.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [concept & "good taste" review] persistent store

On Fri, 2010-12-17 at 10:09 -0800, Tony Luck wrote:
> On Thu, Dec 16, 2010 at 10:28 PM, Tony Luck <tony.luck@...il.com> wrote:
> >> The _only_ valid reason for persistent storage is for things like
> >> oopses that kill the machine.
> >
> > Maybe I misunderstood what "KMSG_DUMP_OOPS" meant ... it
> > looked to me like this code is used for non-fatal OOPsen - ones
> > that will be logged to /var/log/messages.
> 
> Thinking about this a bit more I see my experiments with
> this were hopelessly naive. There is no way to know at
> "oops" time whether the problem is going to turn out to
> be minor or fatal.  So the right thing to do here is assume
> the worst and squirrel the data away safely just in case
> death is imminent.

To be honest, this is what I'd recommend even if you could tell the
difference.  A lot of the oopses I see were triggered by something
non-fatal (usually a WARN_ON()) earlier in the sequence.  Without seeing
the preceding WARN_ON() data, the oops is usually terrifically hard to
diagnose (often just a NULL or junk pointer deref).

James


--
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/