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

Naoya Horiguchi
2012-08-23T20:31:39Z

On Thu, Aug 23, 2012 at 05:22:11PM +0800, Fengguang Wu wrote:
> On Wed, Aug 22, 2012 at 11:17:34AM -0400, Naoya Horiguchi wrote:
> > From: Wu Fengguang <fengguang.wu@intel.com>
> >
> > 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 That's no longer valid with your next patch.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.

yes, that's right.

> So it may also need to
> update comments in memory-failure.c and Documentation/vm/hwpoison.txt

OK. I'll add it in the next version.

> > 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.

Yes.

Thanks,
Naoya

> > Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> > ---
> > 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