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Subject: Re: [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for
 HWPOISON page optionally
From: Huang Ying <ying.huang@intel.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        Andi Kleen <andi@firstfloor.org>, "Luck, Tony" <tony.luck@intel.com>,
        Dean Nelson <dnelson@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>
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References: <1294908168.4596.58.camel@yhuang-dev>
	 <4D2ED737.6050802@redhat.com>
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Date: Fri, 14 Jan 2011 09:37:16 +0800
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On Thu, 2011-01-13 at 18:43 +0800, Avi Kivity wrote:
> On 01/13/2011 10:42 AM, Huang Ying wrote:
> > Make __get_user_pages return -EHWPOISON for HWPOISON page only if
> > FOLL_HWPOISON is specified.  With this patch, the interested callers
> > can distinguish HWPOISON page from general FAULT page, while other
> > callers will still get -EFAULT for pages, so the user space interface
> > need not to be changed.
> >
> > get_user_pages_hwpoison is added as a variant of get_user_pages that
> > can return -EHWPOISON for HWPOISON page.
> >
> > This feature is needed by KVM, where UCR MCE should be relayed to
> > guest for HWPOISON page, while instruction emulation and MMIO will be
> > tried for general FAULT page.
> >
> > The idea comes from Andrew Morton.
> >
> > Signed-off-by: Huang Ying<ying.huang@intel.com>
> > Cc: Andrew Morton<akpm@linux-foundation.org>
> >
> > +#ifdef CONFIG_MEMORY_FAILURE
> > +int get_user_pages_hwpoison(struct task_struct *tsk, struct mm_struct *mm,
> > +			    unsigned long start, int nr_pages, int write,
> > +			    int force, struct page **pages,
> > +			    struct vm_area_struct **vmas);
> > +#else
> 
> Since we'd also like to add get_user_pages_noio(), perhaps adding a 
> flags field to get_user_pages() is better.

Or export __get_user_pages()?

Best Regards,
Huang Ying