Re: hwpoison, shmem: fix data lost issue for 5.15.y

[Mike Kravetz <mike.kravetz@oracle.com>]

On 11/15/22 01:16, HORIGUCHI NAOYA(堀口 直也) wrote:
> On Mon, Nov 14, 2022 at 02:53:51PM -0800, Mike Kravetz wrote:
> > On 11/15/22 07:39, Naoya Horiguchi wrote:
> > > On Mon, Nov 14, 2022 at 05:11:35PM +0100, Greg KH wrote:
> > > > On Mon, Nov 14, 2022 at 10:14:03PM +0900, Naoya Horiguchi wrote:
> > > > > Hi,
> > > > > 
> > > > > I'd like to request the follow commits to be backported to 5.15.y.
> > > > > 
> > > > > - dd0f230a0a80 ("mm: hwpoison: refactor refcount check handling")
> > > > > - 4966455d9100 ("mm: hwpoison: handle non-anonymous THP correctly")
> > > > > - a76054266661 ("mm: shmem: don't truncate page if memory failure happens")
> > > > > 
> > > > > These patches fixed a data lost issue by preventing shmem pagecache from
> > > > > being removed by memory error.  These were not tagged for stable originally,
> > > > > but that's revisited recently.
> > > > 
> > > > And have you tested that these all apply properly (and in which order?)
> > > 
> > > Yes, I've checked that these cleanly apply (without any change) on
> > > 5.15.78 in the above order (i.e. dd0f23 is first, 496645 comes next,
> > > then a76054).
> > > 
> > > > and work correctly?
> > > 
> > > Yes, I ran related testcases in my test suite, and their status changed
> > > FAIL to PASS with these patches.
> > 
> > Hi Naoya,
> > 
> > Just curious if you have plans to do backports for earlier releases?
> 
> I didn't have a clear plan.  I just thought that we should backport to
> earlier kernels if someone want and the patches are applicable easily
> enough and well-tested.
> 
> > 
> > If not, I can start that effort.  We have seen data loss/corruption because of
> > this on a 4.14 based release.   So, I would go at least that far back.
> 
> Thank you for raising hand, that's really helpful.
> 
> Maybe dd0f230a0a80 ("[PATCH] hugetlbfs: don't delete error page from
> pagecbache") should be considered to backport together, because it's
> the similar issue and reported (a while ago) to fail to backport.

Since dd0f230a0a80 was marked for backports, Greg's automation flags it as
FAILED due to conflicts in earlier releases.  I am not sure if James has
a plan to do backports for dd0f230a0a80.  Again, this is also something I
would help with due to real customer issues.
-- 
Mike Kravetz

> dd0f230a0a80 does not apply cleanly on top of 5.15.78 + the above 3 patches.
> So I need check more and will update my current proposal for 5.15.y.
> 
> Thanks,
> Naoya Horiguchi