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From:   Liam Howlett <liam.howlett@oracle.com>
To:     Hugh Dickins <hughd@google.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>
CC:     Nathan Chancellor <nathan@kernel.org>,
        Qian Cai <quic_qiancai@quicinc.com>,
        "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mark Brown <broonie@kernel.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v6 00/71] Introducing the Maple Tree
Thread-Topic: [PATCH v6 00/71] Introducing the Maple Tree
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Date:   Mon, 28 Feb 2022 14:26:46 +0000
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* Hugh Dickins <hughd@google.com> [220226 18:20]:
> On Sat, 26 Feb 2022, Liam Howlett wrote:
> > * Nathan Chancellor <nathan@kernel.org> [220225 18:00]:
> > > On Fri, Feb 25, 2022 at 03:46:52PM -0500, Qian Cai wrote:
> > > > On Fri, Feb 25, 2022 at 08:23:41PM +0000, Liam Howlett wrote:
> > > > > I just booted an arm64 VM with my build and kasan enabled with no=
 issue.
> > > > > Could you please send me your config file for the build?
> > > >=20
> > > > On linux-next, I just do:
> > > >=20
> > > > $ make arch=3Darm64 defconfig debug.config [1]
> > > >=20
> > > > Then, I just generate some memory pressume into swapping/OOM Killer=
 to
> > > > trigger it.
> > > >=20
> > > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next=
.git/tree/kernel/configs/debug.config
> > >=20
> > > Is the stacktrace [1] related to the conflict that Mark encountered [=
2]
> > > while merging the maple and folio trees? Booting a next-20220223 kern=
el
> > > on my Raspberry Pi 3 and 4 shows constant NULL pointer dereferences
> > > (just ARCH=3Darm and ARCH=3Darm64 defconfigs) and reverting the folio=
 and
> > > maple tree merges makes everything work properly again.
> > >=20
> > > [1]: https://lore.kernel.org/r/YhhRrBpXTFolUAKi@qian/
> > > [2]: https://lore.kernel.org/r/20220224011653.1380557-1-broonie@kerne=
l.org/
> >=20
> > Maybe?  I'm trying to figure out why it's having issues.. I've not been
> > able to reproduce it with just my maple tree branch.  Steven Rostedt
> > found a bad commit that has been fixed in either 20220224, I believe
> > [1].  It might be best to try next-20220225 and see if you have better
> > luck if that's an option.
> >=20
> > [1]:
> > https://lore.kernel.org/linux-fsdevel/f6fb6fd4-dcf2-4326-d25e-9a4a9dad5=
020@fb.com/T/#t
>=20
> Hi Liam, I think I have the beginnings of an answer for Qian's issue,
> details below; but first off, I'd better make my own opinion clear.
>=20
> I think this series, however good it may be so far, is undertested and
> not approaching ready for 5.18, and should not have been pushed via
> git tree into 5.17-rc-late-stage linux-next, subverting Andrew's mmotm.
>=20
> I believe Stephen and Mark should drop it from linux-next for now,
> while linux-next stabilizes for 5.18, while you work on testing and
> fixing, and resubmit rebased to 5.18-rc1 or -rc2 when you're ready.

Hugh,

Thank you for your testing, review, and thoughts on the maple tree.  I
agree with your findings and see the error, although still have
difficulty reproducing on amd64 and arm64 VMs.

Stephen, Please drop the maple tree from linux-next.


Thank you,
Liam=