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charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 06, 2020 at 06:00:13PM -0800, Dan Williams wrote: >On Thu, Feb 6, 2020 at 3:17 PM Wei Yang 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 >> CC: Dan Williams >> --- >> 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? You are right, I missed this point. Thanks -- Wei Yang Help you, Help me