From: Dan Williams <dan.j.williams@intel.com>
To: Wei Yang <richardw.yang@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Oscar Salvador <osalvador@suse.de>,
Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Baoquan He <bhe@redhat.com>,
David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH 1/3] mm/sparsemem: adjust memmap only for SPARSEMEM_VMEMMAP
Date: Thu, 6 Feb 2020 18:00:13 -0800 [thread overview]
Message-ID: <CAPcyv4h9C+QLO0VVn2W97p2sYxP2LocCyxYF+Gzy3tM=DYxH4Q@mail.gmail.com> (raw)
In-Reply-To: <20200206231629.14151-2-richardw.yang@linux.intel.com>
On Thu, Feb 6, 2020 at 3:17 PM Wei Yang <richardw.yang@linux.intel.com> wrote:
>
> Only when SPARSEMEM_VMEMMAP is set, memmap returned from
> section_activate() points to sub-section page struct. Otherwise, memmap
> already points to the whole section page struct.
>
> This means only for SPARSEMEM_VMEMMAP, we need to adjust memmap for
> sub-section case.
>
> Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
> CC: Dan Williams <dan.j.williams@intel.com>
> ---
> mm/sparse.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 586d85662978..b5da121bdd6e 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -886,7 +886,8 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn,
> section_mark_present(ms);
>
> /* Align memmap to section boundary in the subsection case */
> - if (section_nr_to_pfn(section_nr) != start_pfn)
> + if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP) &&
> + section_nr_to_pfn(section_nr) != start_pfn)
Aren't we assured that start_pfn is always section aligned in the
SPARSEMEM case? That's the role of check_pfn_span(). Does the change
have a runtime impact or is this just theoretical?
next prev parent reply other threads:[~2020-02-07 2:00 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-06 23:16 [PATCH 0/3] Fixes "mm/sparsemem: support sub-section hotplug" Wei Yang
2020-02-06 23:16 ` [PATCH 1/3] mm/sparsemem: adjust memmap only for SPARSEMEM_VMEMMAP Wei Yang
2020-02-07 2:00 ` Dan Williams [this message]
2020-02-07 11:06 ` Wei Yang
2020-02-06 23:16 ` [PATCH 2/3] mm/sparsemem: get physical address to page struct instead of virtual address to pfn Wei Yang
2020-02-07 2:19 ` Dan Williams
2020-02-07 3:10 ` Baoquan He
2020-02-07 3:21 ` Dan Williams
2020-02-07 3:36 ` Baoquan He
2020-02-07 4:05 ` Dan Williams
2020-02-07 11:13 ` Wei Yang
2020-02-07 12:14 ` Wei Yang
2020-02-07 16:44 ` Dan Williams
2020-02-07 10:51 ` Wei Yang
2020-02-07 11:26 ` Wei Yang
2020-02-09 13:50 ` Baoquan He
2020-02-09 14:14 ` David Hildenbrand
2020-02-10 0:36 ` Wei Yang
2020-02-07 4:11 ` Baoquan He
2020-02-07 10:53 ` Wei Yang
2020-02-06 23:16 ` [PATCH 3/3] mm/sparsemem: avoid memmap overwrite for non-SPARSEMEM_VMEMMAP Wei Yang
2020-02-07 2:06 ` Dan Williams
2020-02-07 3:50 ` Baoquan He
2020-02-07 11:02 ` Wei Yang
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