linux-kernel - Re: [PATCH][OPROFILE] x86: Use for_each_possible_cpu to allocate msrs (was [PATCH] x86: fix oprofile double free (was Re: Multiple free during oprofile unload))

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]

Message-ID: <20070531060938.GK3429@sequoia.sous-sol.org>
Date:	Wed, 30 May 2007 23:09:38 -0700
From:	Chris Wright <chrisw@...s-sol.org>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	John Levon <levon@...ementarian.org>,
	linux-kernel@...r.kernel.org, chrisw@...s-sol.org,
	alan@...rguk.ukuu.org.uk, davej@...hat.com, ak@....de
Subject: Re: [PATCH][OPROFILE] x86: Use for_each_possible_cpu to allocate
	msrs (was [PATCH] x86: fix oprofile double free (was Re: Multiple
	free during oprofile unload))

* Arnaldo Carvalho de Melo (acme@...hat.com) wrote:
> The fix for the fix needed a fix: allocate_msrs() was using
> for_each_online_cpu(), but nmi_setup uses for_each_possible_cpu(), and
> in my test machine, a Dell Poweredge 1950 I have 2 dual core Xeons,
> which makes for 4 possible cores, but wait, they are HT capable, so...
> 
> [acme@...a linux-2.6.21.3.orig]$ dmesg | grep Allowing
> SMP: Allowing 8 CPUs, 4 hotplug CPUs
> [acme@...a linux-2.6.21.3.orig]$
> 
> We have 8 possible CPUs, but only 4 online, b00m. Fix it by making
> allocate_msrs agree with nmi_setup, i.e. make both use
> for_each_possible_cpu().
> 
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>

Acked-by: Chris Wright <chrisw@...s-sol.org>

Thanks Arnaldo.  I noticed this earlier, but mistakenly didn't consider it
an issue aside of code needing to be cleaned up and for hotplug (which I
thought was already broken for other reasons).  And the Opteron I tested
on has possible == online.  I tested this addition on both the AMD box,
as well as an Intel box with possible > online.  All looks good.

thanks,
-chris
-
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/