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[209.85.220.65]) by mx.google.com with SMTPS id y79sor2412166oia.95.2019.05.04.12.26.25 for (Google Transport Security); Sat, 04 May 2019 12:26:25 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=ZEA36jQG; spf=pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=89cKc/1upzZq+P8Ae4aiD1CFSs15MapYdyaJkCMePtw=; b=ZEA36jQGFApzOqLHos1Afgjgxe9rNS/ZjB4sQ/6NAurA/4xrbI73PN/ZOEu5FxwRbL XYwwoNLJDorIRZwXpEzYdD3GUHah+R5M0I5c+aZKoCS2GM23+OQwe9Xe3M+JNMCNzU8M WZ8l+IuL+PhhWtIEdATHQRv5UYBYYgr+uXAR/kPvYepxWwET7kiie3g8ctsAzf5gf4dq PDqlmx+p99HHQZPjh+kVgwkx9bLwgvSkyqGdg9k+UNwSqCpscalkHK5u9y18xyuQbc6J 7GGPfFHS1FdpVeMwvp2CT+EiuxW276XVhiOZTziUYgg46pcJNCNJ81F1o5nzljG4lxhY kvMA== X-Google-Smtp-Source: APXvYqzgWpwq249atnj9kvwy3BXcHz7i8mu5jxzGWLKmGgXpXfK2Afblv75AdGVNtYoG5P/AWqs7eHQTGU5RPJi9kCk= X-Received: by 2002:aca:b108:: with SMTP id a8mr3478255oif.0.1556997985071; Sat, 04 May 2019 12:26:25 -0700 (PDT) MIME-Version: 1.0 References: <155552633539.2015392.2477781120122237934.stgit@dwillia2-desk3.amr.corp.intel.com> <155552635098.2015392.5460028594173939000.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: From: Dan Williams Date: Sat, 4 May 2019 12:26:13 -0700 Message-ID: Subject: Re: [PATCH v6 03/12] mm/sparsemem: Add helpers track active portions of a section at boot To: Pavel Tatashin Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , Logan Gunthorpe , linux-mm , linux-nvdimm , LKML , David Hildenbrand Content-Type: text/plain; charset="UTF-8" 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, May 2, 2019 at 9:12 AM Pavel Tatashin wrote: > > On Wed, Apr 17, 2019 at 2:53 PM Dan Williams wrote: > > > > Prepare for hot{plug,remove} of sub-ranges of a section by tracking a > > section active bitmask, each bit representing 2MB (SECTION_SIZE (128M) / > > map_active bitmask length (64)). If it turns out that 2MB is too large > > of an active tracking granularity it is trivial to increase the size of > > the map_active bitmap. > > Please mention that 2M on Intel, and 16M on Arm64. > > > > > 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. > > > > Cc: Michal Hocko > > Cc: Vlastimil Babka > > Cc: Logan Gunthorpe > > Signed-off-by: Dan Williams > > --- > > include/linux/mmzone.h | 29 ++++++++++++++++++++++++++++- > > mm/page_alloc.c | 4 +++- > > mm/sparse.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 79 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > > index 6726fc175b51..cffde898e345 100644 > > --- a/include/linux/mmzone.h > > +++ b/include/linux/mmzone.h > > @@ -1175,6 +1175,8 @@ struct mem_section_usage { > > unsigned long pageblock_flags[0]; > > }; > > > > +void section_active_init(unsigned long pfn, unsigned long nr_pages); > > + > > struct page; > > struct page_ext; > > struct mem_section { > > @@ -1312,12 +1314,36 @@ static inline struct mem_section *__pfn_to_section(unsigned long pfn) > > > > extern int __highest_present_section_nr; > > > > +static inline int section_active_index(phys_addr_t phys) > > +{ > > + return (phys & ~(PA_SECTION_MASK)) / SECTION_ACTIVE_SIZE; > > How about also defining SECTION_ACTIVE_SHIFT like this: > > /* BITS_PER_LONG = 2^6 */ > #define BITS_PER_LONG_SHIFT 6 > #define SECTION_ACTIVE_SHIFT (SECTION_SIZE_BITS - BITS_PER_LONG_SHIFT) > #define SECTION_ACTIVE_SIZE (1 << SECTION_ACTIVE_SHIFT) > > The return above would become: > return (phys & ~(PA_SECTION_MASK)) >> SECTION_ACTIVE_SHIFT; > > > +} > > + > > +#ifdef CONFIG_SPARSEMEM_VMEMMAP > > +static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) > > +{ > > + int idx = section_active_index(PFN_PHYS(pfn)); > > + > > + return !!(ms->usage->map_active & (1UL << idx)); > > +} > > +#else > > +static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) > > +{ > > + return 1; > > +} > > +#endif > > + > > #ifndef CONFIG_HAVE_ARCH_PFN_VALID > > static inline int pfn_valid(unsigned long pfn) > > { > > + struct mem_section *ms; > > + > > if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) > > return 0; > > - return valid_section(__nr_to_section(pfn_to_section_nr(pfn))); > > + ms = __nr_to_section(pfn_to_section_nr(pfn)); > > + if (!valid_section(ms)) > > + return 0; > > + return pfn_section_valid(ms, pfn); > > } > > #endif > > > > @@ -1349,6 +1375,7 @@ void sparse_init(void); > > #define sparse_init() do {} while (0) > > #define sparse_index_init(_sec, _nid) do {} while (0) > > #define pfn_present pfn_valid > > +#define section_active_init(_pfn, _nr_pages) do {} while (0) > > #endif /* CONFIG_SPARSEMEM */ > > > > /* > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index f671401a7c0b..c9ad28a78018 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -7273,10 +7273,12 @@ void __init free_area_init_nodes(unsigned long *max_zone_pfn) > > > > /* Print out the early node map */ > > pr_info("Early memory node ranges\n"); > > - for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) > > + for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) { > > pr_info(" node %3d: [mem %#018Lx-%#018Lx]\n", nid, > > (u64)start_pfn << PAGE_SHIFT, > > ((u64)end_pfn << PAGE_SHIFT) - 1); > > + section_active_init(start_pfn, end_pfn - start_pfn); > > + } > > > > /* Initialise every node */ > > mminit_verify_pageflags_layout(); > > diff --git a/mm/sparse.c b/mm/sparse.c > > index f87de7ad32c8..5ef2f884c4e1 100644 > > --- a/mm/sparse.c > > +++ b/mm/sparse.c > > @@ -210,6 +210,54 @@ static inline unsigned long first_present_section_nr(void) > > return next_present_section_nr(-1); > > } > > > > +static unsigned long section_active_mask(unsigned long pfn, > > + unsigned long nr_pages) > > +{ > > + int idx_start, idx_size; > > + phys_addr_t start, size; > > + > > + if (!nr_pages) > > + return 0; > > + > > + start = PFN_PHYS(pfn); > > + size = PFN_PHYS(min(nr_pages, PAGES_PER_SECTION > > + - (pfn & ~PAGE_SECTION_MASK))); > > + size = ALIGN(size, SECTION_ACTIVE_SIZE); > > + > > + idx_start = section_active_index(start); > > + idx_size = section_active_index(size); > > + > > + if (idx_size == 0) > > + return -1; > > + return ((1UL << idx_size) - 1) << idx_start; > > +} > > + > > +void section_active_init(unsigned long pfn, unsigned long nr_pages) > > +{ > > + int end_sec = pfn_to_section_nr(pfn + nr_pages - 1); > > + int i, start_sec = pfn_to_section_nr(pfn); > > + > > + if (!nr_pages) > > + return; > > + > > + for (i = start_sec; i <= end_sec; i++) { > > + struct mem_section *ms; > > + unsigned long mask; > > + unsigned long pfns; > > + > > + pfns = min(nr_pages, PAGES_PER_SECTION > > + - (pfn & ~PAGE_SECTION_MASK)); > > + mask = section_active_mask(pfn, pfns); > > + > > + ms = __nr_to_section(i); > > + pr_debug("%s: sec: %d mask: %#018lx\n", __func__, i, mask); > > + ms->usage->map_active = mask; > > + > > + pfn += pfns; > > + nr_pages -= pfns; > > + } > > +} > > For some reasons the above code is confusing to me. It seems all the > code supposed to do is set all map_active to -1, and trim the first > and last sections (can be the same section of course). So, I would > replace the above two functions with one function like this: > > void section_active_init(unsigned long pfn, unsigned long nr_pages) > { > int end_sec = pfn_to_section_nr(pfn + nr_pages - 1); > int i, idx, start_sec = pfn_to_section_nr(pfn); > struct mem_section *ms; > > if (!nr_pages) > return; > > for (i = start_sec; i <= end_sec; i++) { > ms = __nr_to_section(i); > ms->usage->map_active = ~0ul; > } > > /* Might need to trim active pfns from the beginning and end */ > idx = section_active_index(PFN_PHYS(pfn)); > ms = __nr_to_section(start_sec); > ms->usage->map_active &= (~0ul << idx); > > idx = section_active_index(PFN_PHYS(pfn + nr_pages -1)); > ms = __nr_to_section(end_sec); > ms->usage->map_active &= (~0ul >> (BITS_PER_LONG - idx - 1)); > } I like the cleanup, but one of the fixes in v7 resulted in the realization that a given section may be populated twice at init time. For example, enabling that pr_debug() yields: section_active_init: sec: 12 mask: 0x00000003ffffffff section_active_init: sec: 12 mask: 0xe000000000000000 So, the implementation can't blindly clear bits based on the current parameters. However, I'm switching this code over to use bitmap_*() helpers which should help with the readability.