Re: [PATCH 3/3] x86, ras: Add mcsafe_memcpy() function to recover from machine checks

Dan Williams
2015-12-08T21:30:23Z

[ adding nvdimm folks ]

On Fri, Nov 27, 2015 at 2:16 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Luck, Tony <tony.luck@intel.com> wrote:
>
>> On Thu, Nov 12, 2015 at 08:53:13AM +0100, Ingo Molnar wrote:
>> > > +extern phys_addr_t mcsafe_memcpy(void *dst, const void __user *src,
>> > > + unsigned size);
>> >
>> > So what's the longer term purpose, where will mcsafe_memcpy() be used?
>>
>> The initial plan is to use this for file systems backed by NVDIMMs. They will
>> have a large amount of memory, and we have a practical recovery path - return
>> -EIO just like legacy h/w.
>>
>> We can look for other places in the kernel where we read large amounts of memory
>> and have some idea how to recover if the memory turns out to be bad.
>
> I see, that's sensible!
>
> Thanks,
>
> Ingo

Is that an "Acked-by"? I'd like to pull this plus Vishal's
gendisk-badblocks patches into a unified libnvdimm-error-handling
branch. We're looking to have v4.5 able to avoid or survive nvdimm
media errors through the pmem driver and DAX paths.