From: fche@redhat.com (Frank Ch. Eigler)
To: "Sylvain GENEVES" <Sylvain.Geneves@inrialpes.fr>
Cc: "oprofile-list@lists.sf.net" <oprofile-list@lists.sf.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Oprofile bug ?
Date: Fri, 12 Nov 2010 16:45:14 -0500 [thread overview]
Message-ID: <y0mlj4yw711.fsf@fche.csb> (raw)
In-Reply-To: <c69374315a434a8bab96c55e4542bc81.squirrel@webmail.inrialpes.fr> (Sylvain GENEVES's message of "Fri, 12 Nov 2010 22:11:05 +0100")
"Sylvain GENEVES" <Sylvain.Geneves@inrialpes.fr> writes:
> [...]
> I'm encountering unexpected behaviour with OProfile when the profiled
> system is under heavy load : "BUG: unable to handle kernel paging request
> at 0000000000004cc3" (full console message is attached).
> [...]
> Anyone has any idea on what is happening ?
Just glancing at that oops & my local random kernel build, it appears
as though this part of arch/x86/kernel/time.c:profile_pc is failing:
unsigned long profile_pc(struct pt_regs *regs)
{
unsigned long pc = instruction_pointer(regs);
if (!user_mode_vm(regs) && in_lock_functions(pc)) {
#ifdef CONFIG_FRAME_POINTER
return *(unsigned long *)(regs->bp + sizeof(long));
#else
^^^^^^^^^^^^^^^^^^
[...]
regs->bp must have been 0x4cbb, which this code turns into an
unchecked dereferences at 0x4cbb+8 = 0x4cc3. I don't have a theory
as to why regs->bp should have that value in it, but the kernel
should probably use probe_kernel_read() or somesuch to validate the
value before dereferencing it.
- FChE
next prev parent reply other threads:[~2010-11-12 21:45 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-12 21:11 Oprofile bug ? Sylvain GENEVES
2010-11-12 21:45 ` Frank Ch. Eigler [this message]
2010-11-13 16:18 ` Peter Zijlstra
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