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Mon, 02 Aug 2021 07:06:32 -0700 (PDT) MIME-Version: 1.0 References: <20210714193542.21857-1-joao.m.martins@oracle.com> <20210714144830.29f9584878b04903079ef7eb@linux-foundation.org> <5642c8c3-cf13-33dc-c617-9d1becfba1b1@oracle.com> In-Reply-To: From: Dan Williams Date: Mon, 2 Aug 2021 07:06:21 -0700 Message-ID: Subject: Re: [PATCH v3 00/14] mm, sparse-vmemmap: Introduce compound pagemaps To: Joao Martins Cc: Matthew Wilcox , Andrew Morton , Linux MM , Vishal Verma , Dave Jiang , Naoya Horiguchi , Jason Gunthorpe , John Hubbard , Jane Chu , Muchun Song , Mike Kravetz , Jonathan Corbet , Linux NVDIMM , Linux Doc Mailing List Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5B85CD017EA9 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=intel-com.20150623.gappssmtp.com header.s=20150623 header.b=o7zchrRz; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=intel.com (policy=none); spf=none (imf21.hostedemail.com: domain of dan.j.williams@intel.com has no SPF policy when checking 209.85.214.173) smtp.mailfrom=dan.j.williams@intel.com X-Stat-Signature: y1mqtacopd1tyhi8azmigxgyiitcefxs X-HE-Tag: 1627913193-74979 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 Mon, Aug 2, 2021 at 3:41 AM Joao Martins wrote: > > > > On 7/28/21 12:23 AM, Dan Williams wrote: > > On Thu, Jul 22, 2021 at 3:54 AM Joao Martins wrote: > > [..] > >>> The folio work really touches the page > >>> cache for now, and this seems mostly to touch the devmap paths. > >>> > >> /me nods -- it really is about devmap infra for usage in device-dax for persistent memory. > >> > >> Perhaps I should do s/pagemaps/devmap/ throughout the series to avoid confusion. > > > > I also like "devmap" as a more accurate name. It matches the PFN_DEV > > and PFN_MAP flags that decorate DAX capable pfn_t instances. It also > > happens to match a recommendation I gave to Ira for his support for > > supervisor protection keys with devmap pfns. > > > /me nods > > Additionally, I think I'll be reordering the patches for more clear/easier > bisection i.e. first introducing compound pages for devmap, fixing associated > issues wrt to the slow pinning and then introduce vmemmap deduplication for > devmap. > > It should look like below after the reordering from first patch to last. > Let me know if you disagree. > > memory-failure: fetch compound_head after pgmap_pfn_valid() > mm/page_alloc: split prep_compound_page into head and tail subparts > mm/page_alloc: refactor memmap_init_zone_device() page init > mm/memremap: add ZONE_DEVICE support for compound pages > device-dax: use ALIGN() for determining pgoff > device-dax: compound devmap support > mm/gup: grab head page refcount once for group of subpages > mm/sparse-vmemmap: add a pgmap argument to section activation > mm/sparse-vmemmap: refactor core of vmemmap_populate_basepages() to helper > mm/hugetlb_vmemmap: move comment block to Documentation/vm > mm/sparse-vmemmap: populate compound devmaps > mm/page_alloc: reuse tail struct pages for compound devmaps > mm/sparse-vmemmap: improve memory savings for compound pud geometry LGTM.