Re: [PATCH v3 00/15] HWPOISON: soft offline rework

From: "HORIGUCHI NAOYA(堀口　直也)" <naoya.horiguchi@nec.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "nao.horiguchi@gmail.com" <nao.horiguchi@gmail.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"mhocko@kernel.org" <mhocko@kernel.org>,
	"mike.kravetz@oracle.com" <mike.kravetz@oracle.com>,
	"osalvador@suse.de" <osalvador@suse.de>,
	"tony.luck@intel.com" <tony.luck@intel.com>,
	"david@redhat.com" <david@redhat.com>,
	"aneesh.kumar@linux.vnet.ibm.com"
	<aneesh.kumar@linux.vnet.ibm.com>,
	"zeil@yandex-team.ru" <zeil@yandex-team.ru>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 00/15] HWPOISON: soft offline rework
Date: Wed, 24 Jun 2020 23:01:41 +0000	[thread overview]
Message-ID: <20200624230140.GA13052@hori.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <20200624154947.2f41c426d4b83fb9241d8584@linux-foundation.org>

On Wed, Jun 24, 2020 at 03:49:47PM -0700, Andrew Morton wrote:
> On Wed, 24 Jun 2020 22:36:18 +0000 HORIGUCHI NAOYA(堀口　直也) <naoya.horiguchi@nec.com> wrote:
> 
> > On Wed, Jun 24, 2020 at 12:17:42PM -0700, Andrew Morton wrote:
> > > On Wed, 24 Jun 2020 15:01:22 +0000 nao.horiguchi@gmail.com wrote:
> > > 
> > > > I rebased soft-offline rework patchset [1][2] onto the latest mmotm.  The
> > > > rebasing required some non-trivial changes to adjust, but mainly that was
> > > > straightforward.  I confirmed that the reported problem doesn't reproduce on
> > > > compaction after soft offline.  For more precise description of the problem
> > > > and the motivation of this patchset, please see [2].
> > > > 
> > > > I think that the following two patches in v2 are better to be done with
> > > > separate work of hard-offline rework, so it's not included in this series.
> > > > 
> > > >   - mm,hwpoison: Take pages off the buddy when hard-offlining
> > > >   - mm/hwpoison-inject: Rip off duplicated checks
> > > > 
> > > > These two are not directly related to the reported problem, so they seems
> > > > not urgent.  And the first one breaks num_poisoned_pages counting in some
> > > > testcases, and The second patch needs more consideration about commented point.
> > > > 
> > > 
> > > It would be nice to have some sort of overview of the patch series in
> > > this [0/n] email.
> > > 
> > > > [1] v1: https://lore.kernel.org/linux-mm/1541746035-13408-1-git-send-email-n-horiguchi@ah.jp.nec.com/
> > > > [2] v2: https://lore.kernel.org/linux-mm/20191017142123.24245-1-osalvador@suse.de/
> > > 
> > > The above have such, but are they up to date?
> > 
> > The description of the problem doesn't change, but there're some new patches
> > and some patches are postponed, so I should've added an overview of this series:
> > 
> > - patch 1, 2 are cleanups.
> > - patch 3, 4, 5 change the precondition when calling memory_failure(). Previously
> >   we sometimes call it with holding refcount of the target page and somtimes call
> >   without holding it, and we passed a flag of whether refcount was taken out of
> >   memory_failure().  It was confusing and caused code more complex than needed.
> > - patch 6-10 are cleanups.
> > - patch 11 introduces new logic to remove the error page from buddy allocator,
> >   which is also applied to the path of soft-offling in-use pages in patch 12.
> > - patch 13 is basically a refactoring but I added some adjustment to make sure
> >   that the freed page is surely sent back to buddy instead of being kept in pcplist,
> >   which is based on discussion in v2.
> > - patch 14 fixes the inconsistency of return values between injection interfaces.
> > - patch 15 is a new patch to complement missing code found in code review for
> >   previous version.
> > 
> > Core change is in patch 11 and 12, and the others are kind of cleanup/refactoring.
> 
> And all the other words in
> https://lore.kernel.org/linux-mm/1541746035-13408-1-git-send-email-n-horiguchi@ah.jp.nec.com/
> are still accurate and complete?

Yes, they are.

- Naoya