Re: [PATCH RESEND v6 1/9] pagemap: Introduce ->memory_failure()

[Jane Chu]

Hi, ShiYang,

So I applied the v6 patch series to my 5.14-rc3 as it's what you 
indicated is what v6 was based at, and injected a hardware poison.

I'm seeing the same problem that was reported a while ago after the
poison was consumed - in the SIGBUS payload, the si_addr is missing:

** SIGBUS(7): canjmp=1, whichstep=0, **
** si_addr(0x(nil)), si_lsb(0xC), si_code(0x4, BUS_MCEERR_AR) **

The si_addr ought to be 0x7f6568000000 - the vaddr of the first page
in this case.

Something is not right...

thanks,
-jane


On 8/5/2021 6:17 PM, Jane Chu wrote:
> The filesystem part of the pmem failure handling is at minimum built
> on PAGE_SIZE granularity - an inheritance from general memory_failure 
> handling.  However, with Intel's DCPMEM technology, the error blast
> radius is no more than 256bytes, and might get smaller with future
> hardware generation, also advanced atomic 64B write to clear the poison.
> But I don't see any of that could be incorporated in, given that the
> filesystem is notified a corruption with pfn, rather than an exact
> address.
>
> So I guess this question is also for Dan: how to avoid unnecessarily
> repairing a PMD range for a 256B corrupt range going forward?
>
> thanks,
> -jane
>
>
> On 7/30/2021 3:01 AM, Shiyang Ruan wrote:
> > When memory-failure occurs, we call this function which is implemented
> > by each kind of devices.  For the fsdax case, pmem device driver
> > implements it.  Pmem device driver will find out the filesystem in which
> > the corrupted page located in.  And finally call filesystem handler to
> > deal with this error.
> >
> > The filesystem will try to recover the corrupted data if necessary.