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

From: Mike Kravetz <mike.kravetz@oracle.com>
To: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: "HORIGUCHI NAOYA(堀口　直也)" <naoya.horiguchi@nec.com>,
	"Greg KH" <gregkh@linuxfoundation.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"Yang Shi" <shy828301@gmail.com>,
	"James Houghton" <jthoughton@google.com>,
	"Muchun Song" <songmuchun@bytedance.com>,
	"Miaohe Lin" <linmiaohe@huawei.com>,
	"Andrew Morton" <akpm@linux-foundation.org>
Subject: Re: hwpoison, shmem: fix data lost issue for 5.15.y
Date: Tue, 15 Nov 2022 19:48:42 -0800	[thread overview]
Message-ID: <Y3RdmvpUq3XzYqq+@monkey> (raw)
In-Reply-To: <20221115063912.GA3928893@u2004>

On 11/15/22 15:39, Naoya Horiguchi wrote:
> On Mon, Nov 14, 2022 at 05:30:29PM -0800, Mike Kravetz wrote:
> > 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
> 
> # I meant 8625147cafaa, sorry if the wrong commit ID confused you.
> 
> I tested with 8625147cafaa too, and it made hugetlb-related testcases
> passed.
<snip>
> We need to slightly modify 8625147cafaa to apply to 5.15.y.  So in summary,
> my updated suggestion for 5.15.y is like below:
> 
> - [1/4] cherry-pick dd0f230a0a80 ("mm: hwpoison: refactor refcount check handling")
> - [2/4] cherry-pick 4966455d9100 ("mm: hwpoison: handle non-anonymous THP correctly")
> - [3/4] cherry-pick a76054266661 ("mm: shmem: don't truncate page if memory failure happens")
> - [4/4] apply the following patch (as a modified version of 8625147cafaa)

Hi Naoya,

Just curious, do you have automated tests for this?  I wanted test backports
to each stable release.  I could manually test, but that would be a bit
involved and was hoping you had something automated.
-- 
Mike Kravetz