From: Michal Hocko <mhocko@kernel.org>
To: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: "Dan Williams" <dan.j.williams@intel.com>,
"Linux MM" <linux-mm@kvack.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
"Pasha Tatashin" <pavel.tatashin@microsoft.com>,
"Dave Hansen" <dave.hansen@intel.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
rppt@linux.vnet.ibm.com, "Ingo Molnar" <mingo@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
yi.z.zhang@linux.intel.com
Subject: Re: [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap
Date: Wed, 10 Oct 2018 19:24:51 +0200 [thread overview]
Message-ID: <20181010172451.GK5873@dhcp22.suse.cz> (raw)
In-Reply-To: <f97de51c-67dd-99b2-754e-0685cac06699@linux.intel.com>
On Wed 10-10-18 09:39:08, Alexander Duyck wrote:
> On 10/10/2018 2:58 AM, Michal Hocko wrote:
> > On Tue 09-10-18 13:26:41, Alexander Duyck wrote:
> > [...]
> > > I would think with that being the case we still probably need the call to
> > > __SetPageReserved to set the bit with the expectation that it will not be
> > > cleared for device-pages since the pages are not onlined. Removing the call
> > > to __SetPageReserved would probably introduce a number of regressions as
> > > there are multiple spots that use the reserved bit to determine if a page
> > > can be swapped out to disk, mapped as system memory, or migrated.
> >
> > PageReserved is meant to tell any potential pfn walkers that might get
> > to this struct page to back off and not touch it. Even though
> > ZONE_DEVICE doesn't online pages in traditional sense it makes those
> > pages available for further use so the page reserved bit should be
> > cleared.
>
> So from what I can tell that isn't necessarily the case. Specifically if the
> pagemap type is MEMORY_DEVICE_PRIVATE or MEMORY_DEVICE_PUBLIC both are
> special cases where the memory may not be accessible to the CPU or cannot be
> pinned in order to allow for eviction.
Could you give me an example please?
> The specific case that Dan and Yi are referring to is for the type
> MEMORY_DEVICE_FS_DAX. For that type I could probably look at not setting the
> reserved bit. Part of me wants to say that we should wait and clear the bit
> later, but that would end up just adding time back to initialization. At
> this point I would consider the change more of a follow-up optimization
> rather than a fix though since this is tailoring things specifically for DAX
> versus the other ZONE_DEVICE types.
I thought I have already made it clear that these zone device hacks are
not acceptable to the generic hotplug code. If the current reserve bit
handling is not correct then give us a specific reason for that and we
can start thinking about the proper fix.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-10-10 17:24 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-25 20:18 [PATCH v5 0/4] Address issues slowing persistent memory initialization Alexander Duyck
2018-09-25 20:19 ` [PATCH v5 1/4] mm: Remove now defunct NO_BOOTMEM from depends list for deferred init Alexander Duyck
2018-09-25 21:05 ` Mike Rapoport
2018-09-25 20:20 ` [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning Alexander Duyck
2018-09-25 20:26 ` Dave Hansen
2018-09-25 20:38 ` Alexander Duyck
2018-09-25 22:14 ` Dave Hansen
2018-09-25 22:27 ` Alexander Duyck
2018-09-26 7:38 ` Michal Hocko
2018-09-26 15:24 ` Alexander Duyck
2018-09-26 15:39 ` Michal Hocko
2018-09-26 15:41 ` Dave Hansen
2018-09-26 16:18 ` Alexander Duyck
2018-09-26 15:36 ` Dave Hansen
2018-09-26 22:36 ` Andrew Morton
2018-09-25 20:20 ` [PATCH v5 3/4] mm: Create non-atomic version of SetPageReserved for init use Alexander Duyck
2018-09-25 20:21 ` [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Alexander Duyck
2018-09-26 7:55 ` Michal Hocko
2018-09-26 18:25 ` Alexander Duyck
2018-09-26 18:52 ` Dan Williams
2018-09-27 11:20 ` Michal Hocko
2018-09-27 11:09 ` Michal Hocko
2018-09-27 12:25 ` Oscar Salvador
2018-09-27 13:13 ` Michal Hocko
2018-09-27 14:50 ` Oscar Salvador
2018-09-27 15:41 ` David Hildenbrand
2018-09-28 8:12 ` Oscar Salvador
2018-09-28 8:44 ` Oscar Salvador
2018-09-28 15:50 ` Dan Williams
2018-09-27 12:32 ` Oscar Salvador
2018-10-08 21:01 ` Dan Williams
2018-10-08 21:38 ` Alexander Duyck
2018-10-08 22:00 ` Dan Williams
2018-10-08 22:07 ` Alexander Duyck
2018-10-08 22:36 ` Alexander Duyck
2018-10-08 22:59 ` Dan Williams
2018-10-08 23:34 ` [mm PATCH] memremap: Fix reference count for pgmap in devm_memremap_pages Alexander Duyck
2018-10-09 0:20 ` Dan Williams
2018-10-09 17:00 ` [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Yi Zhang
2018-10-09 18:04 ` Dan Williams
2018-10-09 20:26 ` Alexander Duyck
2018-10-09 21:19 ` Dan Williams
2018-10-10 12:52 ` Yi Zhang
2018-10-10 15:27 ` Alexander Duyck
2018-10-11 8:17 ` Yi Zhang
2018-10-10 9:58 ` Michal Hocko
2018-10-10 16:39 ` Alexander Duyck
2018-10-10 17:24 ` Michal Hocko [this message]
2018-10-10 17:39 ` Alexander Duyck
2018-10-10 17:53 ` Michal Hocko
2018-10-10 18:13 ` Alexander Duyck
2018-10-10 18:52 ` Michal Hocko
2018-10-11 8:55 ` Michal Hocko
2018-10-11 17:38 ` Alexander Duyck
2018-10-11 18:22 ` Dan Williams
2018-10-17 7:52 ` Michal Hocko
2018-10-17 15:02 ` Alexander Duyck
2018-10-29 14:12 ` Michal Hocko
2018-10-29 15:59 ` Alexander Duyck
2018-10-29 16:35 ` Michal Hocko
2018-10-29 17:01 ` Alexander Duyck
2018-10-29 17:24 ` Michal Hocko
2018-10-29 17:34 ` Dan Williams
2018-10-29 17:45 ` Michal Hocko
2018-10-29 17:42 ` Alexander Duyck
2018-10-29 18:18 ` Michal Hocko
2018-10-29 19:59 ` Alexander Duyck
2018-10-30 6:29 ` Michal Hocko
2018-10-30 6:55 ` Dan Williams
2018-10-30 8:17 ` Michal Hocko
2018-10-30 15:57 ` Dan Williams
2018-10-30 8:05 ` Oscar Salvador
2018-10-29 15:49 ` Dan Williams
2018-10-29 15:56 ` Michal Hocko
2018-10-10 18:18 ` Dan Williams
2018-10-11 8:39 ` Yi Zhang
2018-10-11 15:38 ` Alexander Duyck
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