On Wed, 13 Aug 2014, Fengguang Wu wrote:
> The 0day boot test robot hits messed up BUG lines like
>
> [ 25.732010] BUG: unable to handle kernel paging requestrun: /lkp/wfg/sr at
> 000000000000d908
> [ 24.986598] BUG: unable to handle kernel run: /lkp/wfg/srpaging request at
> 000000000000d908
> [ 24.914406] BUG: unable to handle kernel run: /lkp/wfg/srearly console in
> decompress_kernel
>
> Which makes the generated bug ID not stable and hence not bisectable.
>
> Fix it by printing the BUG message in one shot.
>
> Signed-off-by: Fengguang Wu <[email protected]>
> ---
> arch/x86/mm/fault.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 3664279..f3e0e0a 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -599,13 +599,13 @@ show_fault_oops(struct pt_regs *regs, unsigned long
> error_code,
> printk(nx_warning, from_kuid(&init_user_ns,
> current_uid()));
> }
>
> - printk(KERN_ALERT "BUG: unable to handle kernel ");
> if (address < PAGE_SIZE)
> - printk(KERN_CONT "NULL pointer dereference");
> + printk(KERN_ALERT "BUG: unable to handle kernel NULL pointer
> dereference at %p\n",
> + (void *) address);
> else
> - printk(KERN_CONT "paging request");
> + printk(KERN_ALERT "BUG: unable to handle kernel NULL pointer
> paging request at %p\n",
> + (void *) address);
>
> - printk(KERN_CONT " at %p\n", (void *) address);
> printk(KERN_ALERT "IP:");
> printk_address(regs->ip);
>
That's been around forever, but I trust that an automated boot testing
robot would find it more troublesome than most, so I agree it needs to be
fixed. One problem: it changes the message from
BUG: unable to handle kernel paging request at %p
to
BUG: unable to handle kernel NULL pointer paging request at %p
and the test for address < PAGE_SIZE is supposed to be the determining
factor on whether it is a "NULL pointer" or not. When that's fixed:
Acked-by: David Rientjes <[email protected]>
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