linux-kernel - Re: [PATCH] perf, x86: Fall back to vmalloc for BTS buffer allocation

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Message-ID: <20140910144012.GI4120@two.firstfloor.org>
Date:	Wed, 10 Sep 2014 16:40:12 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	mingo@...nel.org, eranian@...gle.com, tglx@...utronix.de,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] perf, x86: Fall back to vmalloc for BTS buffer
 allocation

> We did this once, and that blew up big time.
> 
> Even now, vmalloc_fault() has a very explicit:
> 
>   WARN_ON_ONCE(in_nmi());
> 
> So this isn't going to happen until you fix that.

Good point.

We just need to call vmalloc_sync_all at allocation time,
no need to change vmalloc_fault.

-Andi



-- 
ak@...ux.intel.com -- Speaking for myself only.
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