Re: [PATCH 2/3] HWPOISON: report sticky EIO for poisoned file

[Fengguang Wu]

On Wed, Aug 22, 2012 at 11:17:34AM -0400, Naoya Horiguchi wrote:
> From: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> 
> This makes the EIO reports on write(), fsync(), or the NFS close()
> sticky enough. The only way to get rid of it may be
> 
> 	echo 3 > /proc/sys/vm/drop_caches

That's no longer valid with your next patch. If I understand it right,
the EIO will only go away after truncate. So it may also need to
update comments in memory-failure.c and Documentation/vm/hwpoison.txt

> Note that the impacted process will only be killed if it mapped the page.
> XXX
> via read()/write()/fsync() instead of memory mapped reads/writes, simply
> because it's very hard to find them.
 
Please remove the above scratched texts.

> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> ---
>  include/linux/pagemap.h | 13 +++++++++++++
>  mm/filemap.c            | 11 +++++++++++
>  mm/memory-failure.c     |  2 +-
>  3 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git v3.6-rc1.orig/include/linux/pagemap.h v3.6-rc1/include/linux/pagemap.h
> index e42c762..4d8d821 100644
> --- v3.6-rc1.orig/include/linux/pagemap.h
> +++ v3.6-rc1/include/linux/pagemap.h
> @@ -24,6 +24,7 @@ enum mapping_flags {
>  	AS_ENOSPC	= __GFP_BITS_SHIFT + 1,	/* ENOSPC on async write */
>  	AS_MM_ALL_LOCKS	= __GFP_BITS_SHIFT + 2,	/* under mm_take_all_locks() */
>  	AS_UNEVICTABLE	= __GFP_BITS_SHIFT + 3,	/* e.g., ramdisk, SHM_LOCK */
> +	AS_HWPOISON	= __GFP_BITS_SHIFT + 4,	/* hardware memory corruption */
>  };
>  
>  static inline void mapping_set_error(struct address_space *mapping, int error)
> @@ -53,6 +54,18 @@ static inline int mapping_unevictable(struct address_space *mapping)
>  	return !!mapping;
>  }
>  
> +#ifdef CONFIG_MEMORY_FAILURE
> +static inline int mapping_hwpoison(struct address_space *mapping)
> +{
> +	return test_bit(AS_HWPOISON, &mapping->flags);
> +}
> +#else
> +static inline int mapping_hwpoison(struct address_space *mapping)
> +{
> +	return 0;
> +}
> +#endif
> +
>  static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
>  {
>  	return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
> diff --git v3.6-rc1.orig/mm/filemap.c v3.6-rc1/mm/filemap.c
> index fa5ca30..8bdaf57 100644
> --- v3.6-rc1.orig/mm/filemap.c
> +++ v3.6-rc1/mm/filemap.c
> @@ -297,6 +297,8 @@ int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
>  		ret = -ENOSPC;
>  	if (test_and_clear_bit(AS_EIO, &mapping->flags))
>  		ret = -EIO;
> +	if (mapping_hwpoison(mapping))
> +		ret = -EIO;
>  
>  	return ret;
>  }
> @@ -447,6 +449,15 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
>  	VM_BUG_ON(!PageLocked(page));
>  	VM_BUG_ON(PageSwapBacked(page));
>  
> +	/*
> +	 * Hardware corrupted page will be removed from mapping,
> +	 * so we want to deny (possibly) reloading the old data.
> +	 */
> +	if (unlikely(mapping_hwpoison(mapping))) {
> +		error = -EIO;
> +		goto out;
> +	}
> +
>  	error = mem_cgroup_cache_charge(page, current->mm,
>  					gfp_mask & GFP_RECLAIM_MASK);
>  	if (error)
> diff --git v3.6-rc1.orig/mm/memory-failure.c v3.6-rc1/mm/memory-failure.c
> index 79dfb2f..a1e7e00 100644
> --- v3.6-rc1.orig/mm/memory-failure.c
> +++ v3.6-rc1/mm/memory-failure.c
> @@ -652,7 +652,7 @@ static int me_pagecache_dirty(struct page *p, unsigned long pfn)
>  		 * the first EIO, but we're not worse than other parts
>  		 * of the kernel.
>  		 */
> -		mapping_set_error(mapping, EIO);
> +		set_bit(AS_HWPOISON, &mapping->flags);
>  	}
>  
>  	return me_pagecache_clean(p, pfn);
> -- 
> 1.7.11.4
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