Re: [PATCH STABLE v6.1.y] mm/migrate: set swap entry values of THP tail pages properly.

From: Greg KH <gregkh@linuxfoundation.org>
To: David Hildenbrand <david@redhat.com>
Cc: Zi Yan <ziy@nvidia.com>,
	stable@vger.kernel.org, linux-mm@kvack.org,
	Charan Teja Kalla <quic_charante@quicinc.com>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Huang Ying <ying.huang@intel.com>,
	Naoya Horiguchi <naoya.horiguchi@linux.dev>
Subject: Re: [PATCH STABLE v6.1.y] mm/migrate: set swap entry values of THP tail pages properly.
Date: Tue, 5 Mar 2024 22:32:56 +0000	[thread overview]
Message-ID: <2024030527-footrest-cathedral-5e15@gregkh> (raw)
In-Reply-To: <0910e8f0-5490-4d08-ac64-da4077a1e703@redhat.com>

On Tue, Mar 05, 2024 at 11:09:17PM +0100, David Hildenbrand wrote:
> On 05.03.24 23:04, Greg KH wrote:
> > On Tue, Mar 05, 2024 at 11:13:13AM -0500, Zi Yan wrote:
> > > From: Zi Yan <ziy@nvidia.com>
> > > 
> > > The tail pages in a THP can have swap entry information stored in their
> > > private field. When migrating to a new page, all tail pages of the new
> > > page need to update ->private to avoid future data corruption.
> > > 
> > > Signed-off-by: Zi Yan <ziy@nvidia.com>
> > > ---
> > >   mm/migrate.c | 6 +++++-
> > >   1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > What is the git commit id of this change in Linus's tree?
> 
> Unfortunately, we had to do stable-only versions, because the backport
> of the "accidental" fix that removes the per-subpage "private" information
> would be non-trivial, especially for pre-folio-converison times.
> 
> The accidental fix is
> 
> 07e09c483cbef2a252f75d95670755a0607288f5

None of that is obvious at all here, we need loads of documentation in
the changelog text that says all of that please.

thanks,

greg k-h