Re: [PATCH -next v2] mm: hwposion: support recovery from ksm_might_need_to_copy()

[Kefeng Wang]

On 2022/12/12 10:36, Miaohe Lin wrote:
> On 2022/12/9 15:28, Kefeng Wang wrote:
> > When the kernel copy a page from ksm_might_need_to_copy(), but runs
> > into an uncorrectable error, it will crash since poisoned page is
> > consumed by kernel, this is similar to Copy-on-write poison recovery,
> > When an error is detected during the page copy, return VM_FAULT_HWPOISON,
> > which help us to avoid system crash. Note, memory failure on a KSM
> > page will be skipped, but still call memory_failure_queue() to be
> > consistent with general memory failure process.
...
>   
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 908a529bca12..d479811bc311 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1767,7 +1767,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
>   
>   	swapcache = page;
>   	page = ksm_might_need_to_copy(page, vma, addr);
> -	if (unlikely(!page))
> +	if (IS_ERR_OR_NULL(page))
> IMHO, it might be better to install a hwpoison entry here. Or later swapoff ops will trigger
> the uncorrectable error again?
Thanks for you suggestion, will do in v3.
> Thanks,
> Miaohe Lin