From: Michal Hocko <mhocko@kernel.org> To: Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: "Pasha Tatashin" <pavel.tatashin@microsoft.com>, linux-nvdimm <linux-nvdimm@lists.01.org>, "Dave Hansen" <dave.hansen@intel.com>, "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>, "Ingo Molnar" <mingo@kernel.org>, "Linux MM" <linux-mm@kvack.org>, "Jérôme Glisse" <jglisse@redhat.com>, rppt@linux.vnet.ibm.com, "Andrew Morton" <akpm@linux-foundation.org>, "Kirill A. Shutemov" <kirill.shutemov@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 _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
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: 144+ 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 20:18 ` 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 20:19 ` Alexander Duyck 2018-09-25 21:05 ` Mike Rapoport 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 20:20 ` Alexander Duyck 2018-09-25 20:26 ` Dave Hansen 2018-09-25 20:26 ` Dave Hansen 2018-09-25 20:38 ` Alexander Duyck 2018-09-25 20:38 ` Alexander Duyck 2018-09-25 22:14 ` Dave Hansen 2018-09-25 22:14 ` Dave Hansen 2018-09-25 22:14 ` Dave Hansen 2018-09-25 22:27 ` Alexander Duyck 2018-09-25 22:27 ` Alexander Duyck 2018-09-25 22:27 ` Alexander Duyck 2018-09-26 7:38 ` Michal Hocko 2018-09-26 7:38 ` Michal Hocko 2018-09-26 15:24 ` Alexander Duyck 2018-09-26 15:39 ` Michal Hocko 2018-09-26 15:39 ` Michal Hocko 2018-09-26 15:41 ` Dave Hansen 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 2018-09-26 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 20:20 ` 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 2018-09-25 20:21 ` Alexander Duyck 2018-09-26 7:55 ` Michal Hocko 2018-09-26 18:25 ` Alexander Duyck 2018-09-26 18:25 ` Alexander Duyck 2018-09-26 18:52 ` Dan Williams 2018-09-26 18:52 ` Dan Williams 2018-09-27 11:20 ` Michal Hocko 2018-09-27 11:20 ` Michal Hocko 2018-09-27 11:09 ` 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 14:50 ` Oscar Salvador 2018-09-27 14:50 ` Oscar Salvador 2018-09-27 15:41 ` David Hildenbrand 2018-09-27 15:41 ` David Hildenbrand 2018-09-28 8:12 ` Oscar Salvador 2018-09-28 8:12 ` Oscar Salvador 2018-09-28 8:44 ` Oscar Salvador 2018-09-28 8:44 ` Oscar Salvador 2018-09-28 15:50 ` Dan Williams 2018-09-28 15:50 ` Dan Williams 2018-09-27 12:32 ` Oscar Salvador 2018-10-08 21:01 ` Dan Williams 2018-10-08 21:01 ` Dan Williams 2018-10-08 21:38 ` Alexander Duyck 2018-10-08 21:38 ` Alexander Duyck 2018-10-08 22:00 ` Dan Williams 2018-10-08 22:00 ` Dan Williams 2018-10-08 22:00 ` Dan Williams 2018-10-08 22:07 ` Alexander Duyck 2018-10-08 22:07 ` Alexander Duyck 2018-10-08 22:36 ` 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 2018-10-08 23:34 ` Alexander Duyck 2018-10-09 0:20 ` Dan Williams 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 17:00 ` Yi Zhang 2018-10-09 18:04 ` Dan Williams 2018-10-09 18:04 ` Dan Williams 2018-10-09 20:26 ` Alexander Duyck 2018-10-09 20:26 ` Alexander Duyck 2018-10-09 21:19 ` Dan Williams 2018-10-09 21:19 ` Dan Williams 2018-10-10 12:52 ` Yi Zhang 2018-10-10 12:52 ` Yi Zhang 2018-10-10 15:27 ` Alexander Duyck 2018-10-10 15:27 ` Alexander Duyck 2018-10-11 8:17 ` Yi Zhang 2018-10-11 8:17 ` Yi Zhang 2018-10-10 9:58 ` Michal Hocko 2018-10-10 16:39 ` Alexander Duyck 2018-10-10 16:39 ` Alexander Duyck 2018-10-10 17:24 ` Michal Hocko [this message] 2018-10-10 17:24 ` Michal Hocko 2018-10-10 17:39 ` Alexander Duyck 2018-10-10 17:39 ` Alexander Duyck 2018-10-10 17:53 ` Michal Hocko 2018-10-10 17:53 ` Michal Hocko 2018-10-10 18:13 ` Alexander Duyck 2018-10-10 18:13 ` Alexander Duyck 2018-10-10 18:52 ` Michal Hocko 2018-10-10 18:52 ` Michal Hocko 2018-10-11 8:55 ` Michal Hocko 2018-10-11 8:55 ` Michal Hocko 2018-10-11 17:38 ` Alexander Duyck 2018-10-11 18:22 ` Dan Williams 2018-10-11 18:22 ` Dan Williams 2018-10-17 7:52 ` Michal Hocko 2018-10-17 7:52 ` Michal Hocko 2018-10-17 15:02 ` Alexander Duyck 2018-10-17 15:02 ` Alexander Duyck 2018-10-29 14:12 ` Michal Hocko 2018-10-29 14:12 ` Michal Hocko 2018-10-29 15:59 ` Alexander Duyck 2018-10-29 15:59 ` Alexander Duyck 2018-10-29 15:59 ` Alexander Duyck 2018-10-29 16:35 ` Michal Hocko 2018-10-29 16:35 ` Michal Hocko 2018-10-29 17:01 ` Alexander Duyck 2018-10-29 17:24 ` Michal Hocko 2018-10-29 17:24 ` Michal Hocko 2018-10-29 17:34 ` Dan Williams 2018-10-29 17:34 ` Dan Williams 2018-10-29 17:45 ` Michal Hocko 2018-10-29 17:45 ` Michal Hocko 2018-10-29 17:42 ` Alexander Duyck 2018-10-29 17:42 ` Alexander Duyck 2018-10-29 18:18 ` Michal Hocko 2018-10-29 18:18 ` Michal Hocko 2018-10-29 19:59 ` Alexander Duyck 2018-10-29 19:59 ` Alexander Duyck 2018-10-30 6:29 ` Michal Hocko 2018-10-30 6:29 ` Michal Hocko 2018-10-30 6:55 ` Dan Williams 2018-10-30 8:17 ` Michal Hocko 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 15:49 ` Dan Williams 2018-10-29 15:56 ` Michal Hocko 2018-10-10 18:18 ` Dan Williams 2018-10-10 18:18 ` Dan Williams 2018-10-11 8:39 ` Yi Zhang 2018-10-11 8:39 ` Yi Zhang 2018-10-11 15:38 ` Alexander Duyck 2018-10-11 15:38 ` Alexander Duyck
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