linux-kernel - Re: [PATCH] perf_events: improve DS/BTS/PEBS buffer allocation

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]

Message-ID: <1284407360.2275.431.camel@laptop>
Date:	Mon, 13 Sep 2010 21:49:20 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	eranian@...gle.com, linux-kernel@...r.kernel.org, mingo@...e.hu,
	paulus@...ba.org, davem@...emloft.net, fweisbec@...il.com,
	perfmon2-devel@...ts.sf.net, eranian@...il.com,
	robert.richter@....com, markus.t.metzger@...el.com
Subject: Re: [PATCH] perf_events: improve DS/BTS/PEBS buffer allocation

On Mon, 2010-09-13 at 21:35 +0200, Andi Kleen wrote:
> Stephane Eranian <eranian@...gle.com> writes:
> 
> > The DS, BTS, and PEBS memory regions were allocated using kzalloc(), i.e.,
> > requesting contiguous physical memory. There is no such restriction on
> > DS, PEBS and BTS buffers. Using kzalloc() could lead to error in case
> > no contiguous physical memory is available. BTS is requesting 64KB,
> > thus it can cause issues. PEBS is currently only requesting one page.
> > Both PEBS and BTS are static buffers allocated for each CPU at the
> > first user. When the last user exists, the buffers are released.
> 
> DS supports page tables, but I have some doubts it really 
> supports page faults. vmalloc today does page faults. 
> 
> I think the change is a good idea, but it will need vmalloc_sync_all()
> everywhere.

Right, I seem to remember from that last discussion on vmalloc vs NMI
that vmalloc_sync_all() had some issues, or am I totally mis-remembering
that?

But yes, a vmalloc_sync_all() after the vmalloc_node() and this should
indeed work.
--
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/