linux-kernel - RE: [patch 1/5] x86, bts: detect size of DS fields

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Message-ID: <928CFBE8E7CB0040959E56B4EA41A77E4A664285@irsmsx504.ger.corp.intel.com>
Date:	Tue, 17 Mar 2009 12:26:21 +0000
From:	"Metzger, Markus T" <markus.t.metzger@...el.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...or.com" <hpa@...or.com>,
	"markus.t.metzger@...il.com" <markus.t.metzger@...il.com>,
	"roland@...hat.com" <roland@...hat.com>,
	"eranian@...glemail.com" <eranian@...glemail.com>,
	"oleg@...hat.com" <oleg@...hat.com>,
	"Villacis, Juan" <juan.villacis@...el.com>,
	"ak@...ux.jf.intel.com" <ak@...ux.jf.intel.com>
Subject: RE: [patch 1/5] x86, bts: detect size of DS fields

>-----Original Message-----
>From: Ingo Molnar [mailto:mingo@...e.hu]
>Sent: Tuesday, March 17, 2009 11:56 AM
>To: Metzger, Markus T


>the bigger problem is the runtime failure (boot warning) that i
>reported. Hence i cannot apply any new patches yet until that is
>resolved.

I found your email at lkml.org.

I think I found the problem:
  ds_request_bts() needs to allocate a small amount of memory.
  It uses GFP_KERNEL.

Hw-branch-tracer essentially does on_each_cpu(ds_request_bts()).


Since ds_request_bts() is meant to be called on the cpu that should
be traced, it should use GFP_ATOMIC to allow calls from smp_call_function()
and friends.

Would that be acceptable?

thanks and regards,
markus.

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