Re: [PATCH v2] HWPOISON: Fix the handling path of the victimized page frame that belong to non-LUR

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

On Wed, Jun 04, 2014 at 01:48:18PM +0800, Chen Yucong wrote:
> Until now, the kernel has the same policy to handle victimized page frames that
> belong to kernel-space(reserved/slab-subsystem) or non-LRU(unknown page state).
> In other word, the result of handling either of these victimized page frames is
> (IGNORED | FAILED), and the return value of memory_failure() is -EBUSY.
> 
> This patch is to avoid that memory_failure() returns very soon due to the "true"
> value of (!PageLRU(p)), and it also ensures that action_result() can report more
> precise information("reserved kernel",  "kernel slab", and "unknown page state")
> instead of "non LRU", especially for memory errors which are detected by memory-scrubbing.
> 
> Changes since v1: http://www.spinics.net/lists/linux-mm/msg74044.html
>   - Call goto just after if (hwpoison_filter(p)) block, and jump directly to just 
>     before the code determining the page_state, as suggested by Naoya Horiguchi.
> 
> Signed-off-by: Chen Yucong <slaoub@gmail.com>

Looks good to me, thanks!

Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

> ---
>  mm/memory-failure.c |    9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index e3154d9..1340b30 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -862,7 +862,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
>  	struct page *hpage = *hpagep;
>  	struct page *ppage;
>  
> -	if (PageReserved(p) || PageSlab(p))
> +	if (PageReserved(p) || PageSlab(p) || !PageLRU(p))
>  		return SWAP_SUCCESS;
>  
>  	/*
> @@ -1126,9 +1126,6 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
>  					action_result(pfn, "free buddy, 2nd try", DELAYED);
>  				return 0;
>  			}
> -			action_result(pfn, "non LRU", IGNORED);
> -			put_page(p);
> -			return -EBUSY;
>  		}
>  	}
>  
> @@ -1161,6 +1158,9 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
>  		return 0;
>  	}
>  
> +	if (!PageHuge(p) && !PageTransTail(p) && !PageLRU(p))
> +		goto identify_page_state;
> +
>  	/*
>  	 * For error on the tail page, we should set PG_hwpoison
>  	 * on the head page to show that the hugepage is hwpoisoned
> @@ -1210,6 +1210,7 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
>  		goto out;
>  	}
>  
> +identify_page_state:
>  	res = -EBUSY;
>  	/*
>  	 * The first check uses the current page flags which may not have any
> -- 
> 1.7.10.4
> 
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