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

[Chen Yucong <slaoub@gmail.com>]

Hi Andrew Morton,

The following message should be cc'ed to you. This is my negligence.

thx!
cyc
On Wed, 2014-06-04 at 02:41 -0400, Naoya Horiguchi wrote:
> 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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> > 


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