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From: Oscar Salvador <osalvador@suse.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	linux-nvdimm@lists.01.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	akpm@linux-foundation.org, Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH v9 01/12] mm/sparsemem: Introduce struct mem_section_usage
Date: Thu, 6 Jun 2019 19:34:21 +0200	[thread overview]
Message-ID: <20190606173421.GD31194@linux> (raw)
In-Reply-To: <155977187407.2443951.16503493275720588454.stgit@dwillia2-desk3.amr.corp.intel.com>

On Wed, Jun 05, 2019 at 02:57:54PM -0700, Dan Williams wrote:
> Towards enabling memory hotplug to track partial population of a
> section, introduce 'struct mem_section_usage'.
> 
> A pointer to a 'struct mem_section_usage' instance replaces the existing
> pointer to a 'pageblock_flags' bitmap. Effectively it adds one more
> 'unsigned long' beyond the 'pageblock_flags' (usemap) allocation to
> house a new 'subsection_map' bitmap.  The new bitmap enables the memory
> hot{plug,remove} implementation to act on incremental sub-divisions of a
> section.
> 
> The default SUBSECTION_SHIFT is chosen to keep the 'subsection_map' no
> larger than a single 'unsigned long' on the major architectures.
> Alternatively an architecture can define ARCH_SUBSECTION_SHIFT to
> override the default PMD_SHIFT. Note that PowerPC needs to use
> ARCH_SUBSECTION_SHIFT to workaround PMD_SHIFT being a non-constant
> expression on PowerPC.
> 
> The primary motivation for this functionality is to support platforms
> that mix "System RAM" and "Persistent Memory" within a single section,
> or multiple PMEM ranges with different mapping lifetimes within a single
> section. The section restriction for hotplug has caused an ongoing saga
> of hacks and bugs for devm_memremap_pages() users.
> 
> Beyond the fixups to teach existing paths how to retrieve the 'usemap'
> from a section, and updates to usemap allocation path, there are no
> expected behavior changes.
> 
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

-- 
Oscar Salvador
SUSE L3
_______________________________________________
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: Oscar Salvador <osalvador@suse.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: akpm@linux-foundation.org, Michal Hocko <mhocko@suse.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Logan Gunthorpe <logang@deltatee.com>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	linux-mm@kvack.org, linux-nvdimm@lists.01.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v9 01/12] mm/sparsemem: Introduce struct mem_section_usage
Date: Thu, 6 Jun 2019 19:34:21 +0200	[thread overview]
Message-ID: <20190606173421.GD31194@linux> (raw)
In-Reply-To: <155977187407.2443951.16503493275720588454.stgit@dwillia2-desk3.amr.corp.intel.com>

On Wed, Jun 05, 2019 at 02:57:54PM -0700, Dan Williams wrote:
> Towards enabling memory hotplug to track partial population of a
> section, introduce 'struct mem_section_usage'.
> 
> A pointer to a 'struct mem_section_usage' instance replaces the existing
> pointer to a 'pageblock_flags' bitmap. Effectively it adds one more
> 'unsigned long' beyond the 'pageblock_flags' (usemap) allocation to
> house a new 'subsection_map' bitmap.  The new bitmap enables the memory
> hot{plug,remove} implementation to act on incremental sub-divisions of a
> section.
> 
> The default SUBSECTION_SHIFT is chosen to keep the 'subsection_map' no
> larger than a single 'unsigned long' on the major architectures.
> Alternatively an architecture can define ARCH_SUBSECTION_SHIFT to
> override the default PMD_SHIFT. Note that PowerPC needs to use
> ARCH_SUBSECTION_SHIFT to workaround PMD_SHIFT being a non-constant
> expression on PowerPC.
> 
> The primary motivation for this functionality is to support platforms
> that mix "System RAM" and "Persistent Memory" within a single section,
> or multiple PMEM ranges with different mapping lifetimes within a single
> section. The section restriction for hotplug has caused an ongoing saga
> of hacks and bugs for devm_memremap_pages() users.
> 
> Beyond the fixups to teach existing paths how to retrieve the 'usemap'
> from a section, and updates to usemap allocation path, there are no
> expected behavior changes.
> 
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

-- 
Oscar Salvador
SUSE L3


  reply	other threads:[~2019-06-06 17:34 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-05 21:57 [PATCH v9 00/12] mm: Sub-section memory hotplug support Dan Williams
2019-06-05 21:57 ` Dan Williams
2019-06-05 21:57 ` [PATCH v9 01/12] mm/sparsemem: Introduce struct mem_section_usage Dan Williams
2019-06-05 21:57   ` Dan Williams
2019-06-06 17:34   ` Oscar Salvador [this message]
2019-06-06 17:34     ` Oscar Salvador
2019-06-16 13:11   ` Wei Yang
2019-06-16 13:11     ` Wei Yang
2019-06-18 21:56     ` Dan Williams
2019-06-18 21:56       ` Dan Williams
2019-06-19  2:13       ` Wei Yang
2019-06-19  2:13         ` Wei Yang
2019-06-05 21:57 ` [PATCH v9 02/12] mm/sparsemem: Add helpers track active portions of a section at boot Dan Williams
2019-06-05 21:57   ` Dan Williams
2019-06-06 16:55   ` Oscar Salvador
2019-06-06 16:55     ` Oscar Salvador
2019-06-17 22:21   ` Wei Yang
2019-06-17 22:21     ` Wei Yang
2019-06-17 22:32     ` Dan Williams
2019-06-17 22:32       ` Dan Williams
2019-06-18  1:03       ` Wei Yang
2019-06-18  1:03         ` Wei Yang
2019-06-19  3:15       ` Dan Williams
2019-06-05 21:58 ` [PATCH v9 03/12] mm/hotplug: Prepare shrink_{zone, pgdat}_span for sub-section removal Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-18  1:42   ` Wei Yang
2019-06-18  1:42     ` Wei Yang
2019-06-19  3:40     ` Dan Williams
2019-06-05 21:58 ` [PATCH v9 04/12] mm/sparsemem: Convert kmalloc_section_memmap() to populate_section_memmap() Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-06 17:02   ` Oscar Salvador
2019-06-06 17:02     ` Oscar Salvador
2019-06-16  6:06   ` Aneesh Kumar K.V
2019-06-16  6:06     ` Aneesh Kumar K.V
2019-06-05 21:58 ` [PATCH v9 05/12] mm/hotplug: Kill is_dev_zone() usage in __remove_pages() Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-05 21:58 ` [PATCH v9 06/12] mm: Kill is_dev_zone() helper Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-18  3:35   ` Wei Yang
2019-06-18  3:35     ` Wei Yang
2019-06-05 21:58 ` [PATCH v9 07/12] mm/sparsemem: Prepare for sub-section ranges Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-06 17:21   ` Oscar Salvador
2019-06-06 17:21     ` Oscar Salvador
2019-06-06 18:16     ` Dan Williams
2019-06-06 18:16       ` Dan Williams
2019-06-14  8:39   ` David Hildenbrand
2019-06-14  8:39     ` David Hildenbrand
2019-06-05 21:58 ` [PATCH v9 08/12] mm/sparsemem: Support sub-section hotplug Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-07  8:33   ` Oscar Salvador
2019-06-07 15:38     ` Dan Williams
2019-06-07 15:38       ` Dan Williams
2019-06-07 21:41       ` Oscar Salvador
2019-06-05 21:58 ` [PATCH v9 09/12] mm: Document ZONE_DEVICE memory-model implications Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-05 21:58 ` [PATCH v9 10/12] mm/devm_memremap_pages: Enable sub-section remap Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-07  8:56   ` Oscar Salvador
2019-06-07  8:56     ` Oscar Salvador
2019-06-16  7:49   ` Aneesh Kumar K.V
2019-06-05 21:58 ` [PATCH v9 11/12] libnvdimm/pfn: Fix fsdax-mode namespace info-block zero-fields Dan Williams
2019-06-05 21:58   ` Dan Williams
2019-06-06 21:46   ` Andrew Morton
2019-06-06 21:46     ` Andrew Morton
2019-06-06 22:06     ` Dan Williams
2019-06-06 22:06       ` Dan Williams
2019-06-07 19:54       ` Andrew Morton
2019-06-07 20:09         ` Dan Williams
2019-06-12  9:41   ` Aneesh Kumar K.V
2019-06-05 21:59 ` [PATCH v9 12/12] libnvdimm/pfn: Stop padding pmem namespaces to section alignment Dan Williams
2019-06-05 21:59   ` Dan Williams

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