From: Jerome Glisse <jglisse@redhat.com>
To: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
John Hubbard <jhubbard@nvidia.com>,
David Nellans <dnellans@nvidia.com>,
Mark Hairgrove <mhairgrove@nvidia.com>,
Sherry Cheung <SCheung@nvidia.com>,
Subhash Gutti <sgutti@nvidia.com>
Subject: Re: [HMM 12/15] mm/migrate: new memory migration helper for use with device memory v4
Date: Tue, 11 Jul 2017 14:49:19 -0400 [thread overview]
Message-ID: <20170711184919.GD5347@redhat.com> (raw)
In-Reply-To: <7a4478cb-7eb6-2546-e707-1b0f18e3acd4@nvidia.com>
On Tue, Jul 11, 2017 at 11:42:20AM -0700, Evgeny Baskakov wrote:
> On 7/11/17 11:29 AM, Jerome Glisse wrote:
> > Can you test if attached patch helps ? I am having trouble reproducing
> > this
> > from inside a vm.
> >
> > My theory is that 2 concurrent CPU page fault happens. First one manage to
> > start the migration back to system memory but second one see the migration
> > special entry and call migration_entry_wait() which increase page refcount
> > and this happen before first one check page refcount are ok for migration.
> >
> > For regular migration such scenario is ok as the migration bails out and
> > because page is CPU accessible there is no need to kick again the migration
> > for other thread that CPU fault to migrate.
> >
> > I am looking into how i can change migration_entry_wait() not to refcount
> > pages. Let me know if the attached patch helps.
> >
> > Thank you
> > Jerome
>
> Hi Jerome,
>
> Thanks for the update.
>
> Unfortunately, the patch does not help. I just applied it and recompiled the
> kernel. Please find attached a new kernel log and an app log.
>
What are the symptoms ? The program just stop making any progress and you
trigger a sysrequest to dump current states of each threads ? In this
log i don't see migration_entry_wait() anymore but it seems to be waiting
on page lock so there might be 2 issues here.
Jerome
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next prev parent reply other threads:[~2017-07-11 18:49 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-22 16:51 [HMM 00/15] HMM (Heterogeneous Memory Management) v22 Jérôme Glisse
2017-05-22 16:51 ` [HMM 01/15] hmm: heterogeneous memory management documentation Jérôme Glisse
2017-05-22 16:51 ` [HMM 02/15] mm/hmm: heterogeneous memory management (HMM for short) v3 Jérôme Glisse
2017-05-22 16:51 ` [HMM 03/15] mm/hmm/mirror: mirror process address space on device with HMM helpers v3 Jérôme Glisse
2017-05-22 16:51 ` [HMM 04/15] mm/hmm/mirror: helper to snapshot CPU page table v3 Jérôme Glisse
2017-05-22 16:51 ` [HMM 05/15] mm/hmm/mirror: device page fault handler Jérôme Glisse
2017-05-22 16:51 ` [HMM 06/15] mm/memory_hotplug: introduce add_pages Jérôme Glisse
2017-05-22 16:51 ` [HMM 07/15] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v2 Jérôme Glisse
2017-05-22 21:17 ` Dan Williams
2017-05-23 21:36 ` [HMM 07/18] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v3 Jérôme Glisse
2017-05-23 8:36 ` [HMM 07/15] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v2 kbuild test robot
2017-05-22 16:51 ` [HMM 08/15] mm/ZONE_DEVICE: special case put_page() for device private pages Jérôme Glisse
2017-05-22 19:29 ` Dan Williams
2017-05-22 20:14 ` Jerome Glisse
2017-05-22 20:19 ` Dan Williams
2017-05-22 21:14 ` Jerome Glisse
2017-05-22 20:22 ` Hugh Dickins
2017-05-22 21:17 ` Jerome Glisse
2017-05-23 9:34 ` kbuild test robot
2017-05-23 13:23 ` Kirill A. Shutemov
2017-05-23 21:37 ` [HMM 08/18] mm/ZONE_DEVICE: special case put_page() for device private pages v2 Jérôme Glisse
2017-05-22 16:52 ` [HMM 09/15] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v4 Jérôme Glisse
2017-05-23 21:37 ` [HMM 09/18] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v5 Jérôme Glisse
2017-05-22 16:52 ` [HMM 10/15] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v3 Jérôme Glisse
2017-05-22 16:52 ` [HMM 11/15] mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY Jérôme Glisse
2017-05-22 16:52 ` [HMM 12/15] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse
2017-05-23 18:07 ` Reza Arbab
2017-06-27 0:07 ` Evgeny Baskakov
2017-06-30 23:19 ` Evgeny Baskakov
2017-07-01 0:57 ` Jerome Glisse
2017-07-01 2:06 ` Evgeny Baskakov
2017-07-10 22:59 ` Evgeny Baskakov
2017-07-10 23:43 ` Jerome Glisse
2017-07-11 0:17 ` Evgeny Baskakov
2017-07-11 0:54 ` Jerome Glisse
2017-07-20 21:05 ` Evgeny Baskakov
2017-07-10 23:44 ` Evgeny Baskakov
2017-07-11 18:29 ` Jerome Glisse
2017-07-11 18:42 ` Evgeny Baskakov
2017-07-11 18:49 ` Jerome Glisse [this message]
2017-07-11 19:35 ` Evgeny Baskakov
2017-07-13 20:16 ` Jerome Glisse
2017-07-14 5:32 ` Evgeny Baskakov
2017-07-14 19:43 ` Evgeny Baskakov
2017-07-15 0:55 ` Jerome Glisse
2017-07-15 5:04 ` Evgeny Baskakov
2017-07-21 1:00 ` Evgeny Baskakov
2017-07-21 1:33 ` Jerome Glisse
2017-07-21 22:01 ` Evgeny Baskakov
2017-07-25 22:45 ` Evgeny Baskakov
2017-07-26 19:14 ` Jerome Glisse
2017-05-22 16:52 ` [HMM 13/15] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse
2017-05-22 16:52 ` [HMM 14/15] mm/migrate: support un-addressable ZONE_DEVICE page in migration v2 Jérôme Glisse
2017-05-22 16:52 ` [HMM 15/15] mm/migrate: allow migrate_vma() to alloc new page on empty entry v2 Jérôme Glisse
2017-05-23 22:02 ` [HMM 00/15] HMM (Heterogeneous Memory Management) v22 Jerome Glisse
2017-05-23 22:05 ` Andrew Morton
2017-05-24 1:55 ` Balbir Singh
2017-05-24 17:53 ` Jerome Glisse
2017-06-01 2:04 ` Balbir Singh
2017-06-01 22:38 ` Jerome Glisse
2017-06-03 9:18 ` Balbir Singh
2017-05-24 17:20 [HMM 00/15] HMM (Heterogeneous Memory Management) v23 Jérôme Glisse
2017-05-24 17:20 ` [HMM 12/15] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse
2017-05-31 3:59 ` Balbir Singh
2017-06-01 22:35 ` Jerome Glisse
2017-06-07 9:02 ` Balbir Singh
2017-06-07 14:06 ` Jerome Glisse
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