From: Robert Richter <rric@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Zhang, Jun" <jun.zhang@intel.com>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>,
"oprofile-list@lists.sf.net" <oprofile-list@lists.sf.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] Sometimes, there is OOPS happened when we use oprofile.
Date: Wed, 31 Oct 2012 23:45:23 +0100 [thread overview]
Message-ID: <20121031224523.GF4386@ivy.homofaber> (raw)
In-Reply-To: <5091991D.4020202@zytor.com>
On 31.10.12 14:33:17, H. Peter Anvin wrote:
> I'm vaguely concerned about the following:
>
> + * To always return a non-null
> + * stack pointer we fall back to regs as stack if no previous stack
> + * exists.
>
> The logic being that if there is no stack pointer and the stack is
> too empty, to simply assume regs point to the top of the stack? Is
> this possible to ever be actually seen?
I discussed this with Steven too (https://lkml.org/lkml/2012/9/6/322)
and we both had a bad feeling with returning a null pointer by
kernel_stack_pointer() (implemented in version 1 of this patch). It
could be null if tinfo->previous_esp is null (last stack). Not sure
when this may happen.
So using regs as fallback seemed to be ok as this was in for years:
7b6c6c7 x86, 32-bit: fix kernel_trap_sp()
-Robert
prev parent reply other threads:[~2012-10-31 22:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-29 2:33 [PATCH] Sometimes, there is OOPS happened when we use oprofile Zhang, Jun
2012-10-31 21:05 ` Robert Richter
2012-10-31 21:27 ` H. Peter Anvin
2012-10-31 21:33 ` H. Peter Anvin
2012-10-31 22:45 ` Robert Richter [this message]
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