From: Oscar Salvador <osalvador@suse.de>
To: Dan Williams <dan.j.williams@intel.com>, akpm@linux-foundation.org
Cc: Qian Cai <cai@lca.pw>, Michal Hocko <mhocko@suse.com>,
Logan Gunthorpe <logang@deltatee.com>,
David Hildenbrand <david@redhat.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 02/13] mm/sparsemem: Introduce a SECTION_IS_EARLY flag
Date: Mon, 24 Jun 2019 19:54:29 +0200 [thread overview]
Message-ID: <1561398869.3073.4.camel@suse.de> (raw)
In-Reply-To: <156092350358.979959.5817209875548072819.stgit@dwillia2-desk3.amr.corp.intel.com>
On Tue, 2019-06-18 at 22:51 -0700, Dan Williams wrote:
> In preparation for sub-section hotplug, track whether a given section
> was created during early memory initialization, or later via memory
> hotplug. This distinction is needed to maintain the coarse
> expectation
> that pfn_valid() returns true for any pfn within a given section even
> if
> that section has pages that are reserved from the page allocator.
>
> For example one of the of goals of subsection hotplug is to support
> cases where the system physical memory layout collides System RAM and
> PMEM within a section. Several pfn_valid() users expect to just check
> if
> a section is valid, but they are not careful to check if the given
> pfn
> is within a "System RAM" boundary and instead expect pgdat
> information
> to further validate the pfn.
>
> Rather than unwind those paths to make their pfn_valid() queries more
> precise a follow on patch uses the SECTION_IS_EARLY flag to maintain
> the
> traditional expectation that pfn_valid() returns true for all early
> sections.
>
> Link: https://lore.kernel.org/lkml/1560366952-10660-1-git-send-email-
> cai@lca.pw/
> Reported-by: Qian Cai <cai@lca.pw>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
[...]
> @@ -731,7 +732,7 @@ int __meminit sparse_add_one_section(int nid,
> unsigned long start_pfn,
> page_init_poison(memmap, sizeof(struct page) *
> PAGES_PER_SECTION);
>
> section_mark_present(ms);
> - sparse_init_one_section(ms, section_nr, memmap, usage);
> + sparse_init_one_section(ms, section_nr, memmap, usage, 0);
I think this is an improvment, and I really like the idea of leveraring
a new section's flag for this, but I have mixed feelings about the way
to mark a section as an early one.
IMHO, I think that a new "section_mark_early" function would be better
than passing a new flag parameter to sparse_init_one_section().
But I do not feel strong on this:
Reviewed-by: Oscar Salvador <osalvador@suse.de>
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2019-06-24 17:54 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 [this message]
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
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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