Re: [PATCH] [7/16] HWPOISON: x86: Add VM_FAULT_HWPOISON handling to x86 page fault handler v2

[Nick Piggin]

On Wed, Jun 03, 2009 at 08:46:40PM +0200, Andi Kleen wrote:
> 
> Add VM_FAULT_HWPOISON handling to the x86 page fault handler. This is 
> very similar to VM_FAULT_OOM, the only difference is that a different
> si_code is passed to user space and the new addr_lsb field is initialized.
> 
> v2: Make the printk more verbose/unique
> 
> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> 
> ---
>  arch/x86/mm/fault.c |   19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> Index: linux/arch/x86/mm/fault.c
> ===================================================================
> --- linux.orig/arch/x86/mm/fault.c	2009-06-03 19:36:21.000000000 +0200
> +++ linux/arch/x86/mm/fault.c	2009-06-03 19:36:23.000000000 +0200
> @@ -166,6 +166,7 @@
>  	info.si_errno	= 0;
>  	info.si_code	= si_code;
>  	info.si_addr	= (void __user *)address;
> +	info.si_addr_lsb = si_code == BUS_MCEERR_AR ? PAGE_SHIFT : 0;
>  
>  	force_sig_info(si_signo, &info, tsk);
>  }
> @@ -797,10 +798,12 @@
>  }
>  
>  static void
> -do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address)
> +do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
> +	  unsigned int fault)
>  {
>  	struct task_struct *tsk = current;
>  	struct mm_struct *mm = tsk->mm;
> +	int code = BUS_ADRERR;
>  
>  	up_read(&mm->mmap_sem);
>  
> @@ -816,7 +819,15 @@
>  	tsk->thread.error_code	= error_code;
>  	tsk->thread.trap_no	= 14;
>  
> -	force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
> +#ifdef CONFIG_MEMORY_FAILURE
> +	if (fault & VM_FAULT_HWPOISON) {
> +		printk(KERN_ERR
> +	"MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n",
> +			tsk->comm, tsk->pid, address);
> +		code = BUS_MCEERR_AR;
> +	}
> +#endif

If you make VM_FAULT_HWPOISON 0 when !CONFIG_MEMORY_FAILURE, then
you can remove this ifdef, can't you?

> +	force_sig_info_fault(SIGBUS, code, address, tsk);
>  }
>  
>  static noinline void
> @@ -826,8 +837,8 @@
>  	if (fault & VM_FAULT_OOM) {
>  		out_of_memory(regs, error_code, address);
>  	} else {
> -		if (fault & VM_FAULT_SIGBUS)
> -			do_sigbus(regs, error_code, address);
> +		if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON))
> +			do_sigbus(regs, error_code, address, fault);
>  		else
>  			BUG();
>  	}
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