Re: Bug: broken /proc/kcore in 6.13

Alexandre Ferrieux <[email protected]> Fri, 17 Jan 2025 16:28:32 +0100

Newsgroups	org.kernel.vger.linux-trace-users,org.kernel.vger.linux-kernel,org.kvack.linux-mm
Organization	Orange
Message-ID	<[email protected]>


On 17/01/2025 16:19, Alexandre Ferrieux wrote:
> On 17/01/2025 15:44, Lorenzo Stoakes wrote:
>>> Alexandre Ferrieux <[email protected]> wrote:
>>>
>>>> Hi,
>>>>
>>>> Somewhere in the 6.13 branch (not bisected yet, sorry), it stopped being
>>>> possible to disassemble the running kernel from gdb through /proc/kcore.
>> Thanks for the report! Much appreciated.
>>
>> I may try to bisect here also unless you're close to finding the commit that
>> broke this?
>
> I'm currently homing in on copy_page_to_iter_nofault(), will report shortly :)

Hmm, actually, that baby ain't cooperative:

  [Fri Jan 17 15:23:05 2025] trace_kprobe: Could not probe notrace function
  copy_page_to_iter_nofault

... if I cannot insert kprobes to sniff around, I'm a bit stuck :}
So I think you'll reach the goal faster than me !

PS: For your bisection: the last working kernel I know of is Debian's 6.12 final:

  ii  linux-image-6.12.9-amd64         6.12.9-1                         amd64
    Linux 6.12 for 64-bit PCs (signed)