From: Jerome Glisse <jglisse@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Ralph Campbell <rcampbell@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH 4/7] mm/hmm: properly handle migration pmd
Date: Tue, 28 Aug 2018 11:36:59 -0400 [thread overview]
Message-ID: <20180828153658.GA4029@redhat.com> (raw)
In-Reply-To: <20180828152414.GQ10223@dhcp22.suse.cz>
On Tue, Aug 28, 2018 at 05:24:14PM +0200, Michal Hocko wrote:
> On Fri 24-08-18 20:05:46, Zi Yan wrote:
> [...]
> > > + if (!pmd_present(pmd)) {
> > > + swp_entry_t entry = pmd_to_swp_entry(pmd);
> > > +
> > > + if (is_migration_entry(entry)) {
> >
> > I think you should check thp_migration_supported() here, since PMD migration is only enabled in x86_64 systems.
> > Other architectures should treat PMD migration entries as bad.
>
> How can we have a migration pmd entry when the migration is not
> supported?
Not sure i follow here, migration can happen anywhere (assuming
that something like compaction is active or numa or ...). So this
code can face pmd migration entry on architecture that support
it. What is missing here is thp_migration_supported() call to
protect the is_migration_entry() to avoid false positive on arch
which do not support thp migration.
Cheers,
Jerome
next prev parent reply other threads:[~2018-08-28 15:37 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-24 19:25 [PATCH 0/7] HMM updates, improvements and fixes jglisse
2018-08-24 19:25 ` [PATCH 1/7] mm/hmm: fix utf8 jglisse
2018-08-24 19:25 ` [PATCH 2/7] mm/rmap: map_pte() was not handling private ZONE_DEVICE page properly jglisse
2018-08-30 14:05 ` Balbir Singh
2018-08-30 14:34 ` Jerome Glisse
2018-08-30 14:41 ` [PATCH 3/7] mm/rmap: map_pte() was not handling private ZONE_DEVICE page properly v2 jglisse
2018-08-31 9:27 ` Balbir Singh
2018-08-31 16:19 ` Jerome Glisse
2018-09-02 6:58 ` Balbir Singh
2018-08-24 19:25 ` [PATCH 3/7] mm/hmm: fix race between hmm_mirror_unregister() and mmu_notifier callback jglisse
2018-08-30 14:14 ` Balbir Singh
2018-08-24 19:25 ` [PATCH 4/7] mm/hmm: properly handle migration pmd jglisse
2018-08-25 0:05 ` Zi Yan
2018-08-28 0:35 ` Jerome Glisse
2018-08-28 15:24 ` Michal Hocko
2018-08-28 15:36 ` Jerome Glisse [this message]
2018-08-28 15:42 ` Michal Hocko
2018-08-28 15:45 ` Michal Hocko
2018-08-28 15:54 ` Zi Yan
2018-08-28 16:06 ` Jerome Glisse
2018-08-28 16:10 ` Michal Hocko
2018-08-29 17:17 ` [PATCH 4/7] mm/hmm: properly handle migration pmd v2 jglisse
2018-08-24 19:25 ` [PATCH 5/7] mm/hmm: use a structure for update callback parameters jglisse
2018-08-30 23:11 ` Balbir Singh
2018-08-31 16:12 ` Jerome Glisse
2018-08-24 19:25 ` [PATCH 6/7] mm/hmm: invalidate device page table at start of invalidation jglisse
2018-08-24 19:25 ` [PATCH 7/7] mm/hmm: proper support for blockable mmu_notifier jglisse
2018-10-12 18:15 ` [PATCH 0/7] HMM updates, improvements and fixes Jerome Glisse
2018-10-12 21:12 ` Andrew Morton
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