From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 10 May 2019 14:56:54 +0200 From: osalvador@suse.de Subject: Re: [PATCH v8 03/12] mm/sparsemem: Add helpers track active portions of a section at boot In-Reply-To: <155718598213.130019.10989541248734713186.stgit@dwillia2-desk3.amr.corp.intel.com> References: <155718596657.130019.17139634728875079809.stgit@dwillia2-desk3.amr.corp.intel.com> <155718598213.130019.10989541248734713186.stgit@dwillia2-desk3.amr.corp.intel.com> Message-ID: <5ce1d8dfe8e485616f9ade30fade88a5@suse.de> Sender: owner-linux-mm@kvack.org To: Dan Williams Cc: akpm@linux-foundation.org, Michal Hocko , Vlastimil Babka , Logan Gunthorpe , Pavel Tatashin , Jane Chu , linux-nvdimm@lists.01.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On 2019-05-07 01:39, Dan Williams wrote: > Prepare for hot{plug,remove} of sub-ranges of a section by tracking a > sub-section active bitmask, each bit representing a PMD_SIZE span of > the > architecture's memory hotplug section size. > > The implications of a partially populated section is that pfn_valid() > needs to go beyond a valid_section() check and read the sub-section > active ranges from the bitmask. The expectation is that the bitmask > (subsection_map) fits in the same cacheline as the valid_section() > data, > so the incremental performance overhead to pfn_valid() should be > negligible. > > Cc: Michal Hocko > Cc: Vlastimil Babka > Cc: Logan Gunthorpe > Cc: Oscar Salvador > Cc: Pavel Tatashin > Tested-by: Jane Chu > Signed-off-by: Dan Williams Now that the handling is done in pfn/nr_pages, it looks better to me: Reviewed-by: Oscar Salvador Thanks