From: Oscar Salvador <osalvador@suse.de>
To: Dan Williams <dan.j.williams@intel.com>, akpm@linux-foundation.org
Cc: Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>,
Logan Gunthorpe <logang@deltatee.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
linux-mm@kvack.org, linux-nvdimm@lists.01.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v10 09/13] mm/sparsemem: Support sub-section hotplug
Date: Mon, 24 Jun 2019 22:45:29 +0200 [thread overview]
Message-ID: <1561409129.3058.1.camel@suse.de> (raw)
In-Reply-To: <156092354368.979959.6232443923440952359.stgit@dwillia2-desk3.amr.corp.intel.com>
On Tue, 2019-06-18 at 22:52 -0700, Dan Williams wrote:
> The libnvdimm sub-system has suffered a series of hacks and broken
> workarounds for the memory-hotplug implementation's awkward
> section-aligned (128MB) granularity. For example the following
> backtrace
> is emitted when attempting arch_add_memory() with physical address
> ranges that intersect 'System RAM' (RAM) with 'Persistent Memory'
> (PMEM)
> within a given section:
>
> # cat /proc/iomem | grep -A1 -B1 Persistent\ Memory
> 100000000-1ffffffff : System RAM
> 200000000-303ffffff : Persistent Memory (legacy)
> 304000000-43fffffff : System RAM
> 440000000-23ffffffff : Persistent Memory
> 2400000000-43bfffffff : Persistent Memory
> 2400000000-43bfffffff : namespace2.0
>
> WARNING: CPU: 38 PID: 928 at arch/x86/mm/init_64.c:850
> add_pages+0x5c/0x60
> [..]
> RIP: 0010:add_pages+0x5c/0x60
> [..]
> Call Trace:
> devm_memremap_pages+0x460/0x6e0
> pmem_attach_disk+0x29e/0x680 [nd_pmem]
> ? nd_dax_probe+0xfc/0x120 [libnvdimm]
> nvdimm_bus_probe+0x66/0x160 [libnvdimm]
>
> It was discovered that the problem goes beyond RAM vs PMEM collisions
> as
> some platform produce PMEM vs PMEM collisions within a given section.
> The libnvdimm workaround for that case revealed that the libnvdimm
> section-alignment-padding implementation has been broken for a long
> while. A fix for that long-standing breakage introduces as many
> problems
> as it solves as it would require a backward-incompatible change to
> the
> namespace metadata interpretation. Instead of that dubious route [1],
> address the root problem in the memory-hotplug implementation.
>
> Note that EEXIST is no longer treated as success as that is how
> sparse_add_section() reports subsection collisions, it was also
> obviated
> by recent changes to perform the request_region() for 'System RAM'
> before arch_add_memory() in the add_memory() sequence.
>
> [1]: https://lore.kernel.org/r/155000671719.348031.234736316014111923
> 7.stgit@dwillia2-desk3.amr.corp.intel.com
> 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>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2019-06-24 20:45 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-19 5:51 [PATCH v10 00/13] mm: Sub-section memory hotplug support Dan Williams
2019-06-19 5:51 ` [PATCH v10 01/13] mm/sparsemem: Introduce struct mem_section_usage Dan Williams
2019-06-19 5:51 ` [PATCH v10 02/13] mm/sparsemem: Introduce a SECTION_IS_EARLY flag Dan Williams
2019-06-24 17:54 ` Oscar Salvador
2019-06-19 5:51 ` [PATCH v10 03/13] mm/sparsemem: Add helpers track active portions of a section at boot Dan Williams
2019-06-24 17:57 ` Oscar Salvador
2019-06-19 5:51 ` [PATCH v10 04/13] mm/hotplug: Prepare shrink_{zone, pgdat}_span for sub-section removal Dan Williams
2019-06-19 5:52 ` [PATCH v10 05/13] mm/sparsemem: Convert kmalloc_section_memmap() to populate_section_memmap() Dan Williams
2019-06-24 18:00 ` Oscar Salvador
2019-06-19 5:52 ` [PATCH v10 06/13] mm/hotplug: Kill is_dev_zone() usage in __remove_pages() Dan Williams
2019-06-19 5:52 ` [PATCH v10 07/13] mm: Kill is_dev_zone() helper Dan Williams
2019-06-19 5:52 ` [PATCH v10 08/13] mm/sparsemem: Prepare for sub-section ranges Dan Williams
2019-06-20 10:31 ` David Hildenbrand
2019-06-20 16:19 ` Dan Williams
2019-06-20 16:35 ` David Hildenbrand
2019-06-20 16:56 ` Dan Williams
2019-06-24 18:05 ` Oscar Salvador
2019-06-19 5:52 ` [PATCH v10 09/13] mm/sparsemem: Support sub-section hotplug Dan Williams
2019-06-24 20:45 ` Oscar Salvador [this message]
2019-06-19 5:52 ` [PATCH v10 10/13] mm: Document ZONE_DEVICE memory-model implications Dan Williams
2019-06-20 12:30 ` Mike Rapoport
2019-06-19 5:52 ` [PATCH v10 11/13] mm/devm_memremap_pages: Enable sub-section remap Dan Williams
2019-06-19 5:52 ` [PATCH v10 12/13] libnvdimm/pfn: Fix fsdax-mode namespace info-block zero-fields Dan Williams
2019-06-19 16:30 ` Aneesh Kumar K.V
2019-06-19 17:06 ` Dan Williams
2019-06-19 5:52 ` [PATCH v10 13/13] libnvdimm/pfn: Stop padding pmem namespaces to section alignment Dan Williams
2019-06-20 12:30 ` [PATCH v10 00/13] mm: Sub-section memory hotplug support Aneesh Kumar K.V
2019-06-20 16:30 ` Dan Williams
2019-06-20 17:00 ` Oscar Salvador
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