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From: "HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: "nao.horiguchi@gmail.com" <nao.horiguchi@gmail.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"mhocko@kernel.org" <mhocko@kernel.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"mike.kravetz@oracle.com" <mike.kravetz@oracle.com>,
	"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: Tue, 30 Jun 2020 06:50:59 +0000
Message-ID: <20200630065057.GA9777@hori.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <1593426565.3504.6.camel@suse.de>

On Mon, Jun 29, 2020 at 12:29:25PM +0200, Oscar Salvador wrote:
> On Wed, 2020-06-24 at 15:01 +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].
> 
> Hi Naoya,
> 
> Thanks for dusting this off.
> To be honest, I got stuck with the hard offline mode so this delayed
> the resubmission, along other problems.
> 
> > 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.
> 
> I fully agree.
> 
> > Any comment/suggestion/help would be appreciated.
> 
> My "new" version included a patch to make sure we give a chance to
> pages that possibly are in a pcplist.
> Current behavior is that if someone tries to soft-offline such a page,
> we return an error because page count is 0 but page is not in the buddy
> system.
> 
> Since this patchset already landed in the mm tree, I could send it as a
> standalone patch on top if you agree with it.
> 
> My patch looked something like:
> 
> From: Oscar Salvador <osalvador@suse.de>
> Date: Mon, 29 Jun 2020 12:25:11 +0200
> Subject: [PATCH] mm,hwpoison: Drain pcplists before bailing out for
> non-buddy
>  zero-refcount page
> 
> A page with 0-refcount and !PageBuddy could perfectly be a pcppage.
> Currently, we bail out with an error if we encounter such a page,
> meaning that we do not give a chance to handle pcppages.
> 
> Fix this by draining pcplists whenever we find this kind of page
> and retry the check again.
> It might be that pcplists have been spilled into the buddy allocator
> and so we can handle it.
>
> Signed-off-by: Oscar Salvador <osalvador@suse.de>

I'm fine with this patch, so this will be with the next version with
some minor change like moving function comment block together.

Actually I feel we could refactor get_hwpoison_page() with get_any_page()
to handle this kind of pcplist related issues in one place. But this could
be more important in hard-offline reworking, and we don't have to do it
in this series.

Thanks,
Naoya Horiguchi

  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24 15:01 nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 01/15] mm,hwpoison: cleanup unused PageHuge() check nao.horiguchi
2020-06-30 23:28   ` Mike Kravetz
2020-06-24 15:01 ` [PATCH v3 02/15] mm, hwpoison: remove recalculating hpage nao.horiguchi
2020-06-30 23:45   ` Mike Kravetz
2020-06-24 15:01 ` [PATCH v3 03/15] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 04/15] mm,madvise: Refactor madvise_inject_error nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 05/15] mm,hwpoison-inject: don't pin for hwpoison_filter nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 06/15] mm,hwpoison: Un-export get_hwpoison_page and make it static nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 07/15] mm,hwpoison: Kill put_hwpoison_page nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 08/15] mm,hwpoison: remove MF_COUNT_INCREASED nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 09/15] mm,hwpoison: remove flag argument from soft offline functions nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 10/15] mm,hwpoison: Unify THP handling for hard and soft offline nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 11/15] mm,hwpoison: Rework soft offline for free pages nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 12/15] mm,hwpoison: Rework soft offline for in-use pages nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 13/15] mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page nao.horiguchi
2020-06-26 16:53   ` Naresh Kamboju
2020-06-28  6:54     ` Naoya Horiguchi
2020-06-29  7:22       ` Stephen Rothwell
2020-06-29  7:33         ` HORIGUCHI NAOYA(堀口 直也)
2020-06-24 15:01 ` [PATCH v3 14/15] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline nao.horiguchi
2020-06-24 15:01 ` [PATCH v3 15/15] mm,hwpoison: introduce MF_MSG_UNSPLIT_THP nao.horiguchi
2020-06-24 19:17 ` [PATCH v3 00/15] HWPOISON: soft offline rework Andrew Morton
2020-06-24 22:36   ` HORIGUCHI NAOYA(堀口 直也)
2020-06-24 22:49     ` Andrew Morton
2020-06-24 23:01       ` HORIGUCHI NAOYA(堀口 直也)
2020-06-26 13:35 ` Qian Cai
2020-06-29 10:29 ` Oscar Salvador
2020-06-30  6:50   ` HORIGUCHI NAOYA(堀口 直也) [this message]
2020-06-30  5:08 ` Qian Cai
2020-06-30  6:35   ` Oscar Salvador
2020-07-01  8:22     ` Oscar Salvador
2020-07-01  9:07       ` HORIGUCHI NAOYA(堀口 直也)
2020-07-14 10:08   ` Oscar Salvador

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