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[209.85.220.65]) by mx.google.com with SMTPS id 12sor9490063ejy.58.2019.05.02.09.12.25 for (Google Transport Security); Thu, 02 May 2019 09:12:26 -0700 (PDT) Received-SPF: pass (google.com: domain of pasha.tatashin@soleen.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@soleen.com header.s=google header.b=ZRcrCjA5; spf=pass (google.com: domain of pasha.tatashin@soleen.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=pasha.tatashin@soleen.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=PmuDEks26u7TosMg6YO9rFojJhi017p7aPym+WIjY/s=; b=ZRcrCjA5yDrtzuhuaxGA218aPuy8sioowVXNbMz96fmtX1Q3YhAiRGlzgamPi0mAvB nixiSO3SdAXaNwXkkyRiwjWAOPYOnlW3ZaGc3IMwRN6X6T0kJBBIeKpYX6/gW3tvhj2v tvfJ/mI0Ws/aUUfRVyG59bggwQfeK8Xo8ncypTOvY/rJGjB4xOUAk10lU9CKRYTM6Nss qYhP5n+dg2IjGEpOo0V8UzIRXLskytJ1Quc1RDZAozElxiQIMW+tW/Jmc5ffpKQiTnp1 eTJ5SHTsoZHRFQxKrcXR5/EFeOHgq/xPq8bvxS678Opw86soN2msVgRGObpkLlonfB/7 eVZg== X-Google-Smtp-Source: APXvYqwyYTUtFEmJ3Pk1Kxl+N/9cXpVtziHTpF16SYo8jOemVRi2MW8HQ4q0f3So4cyRee2cDlyFYKUmjwTvJxrP1fU= X-Received: by 2002:a17:906:4988:: with SMTP id p8mr2289364eju.220.1556813545671; Thu, 02 May 2019 09:12:25 -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: <155552635098.2015392.5460028594173939000.stgit@dwillia2-desk3.amr.corp.intel.com> From: Pavel Tatashin Date: Thu, 2 May 2019 12:12:14 -0400 Message-ID: Subject: Re: [PATCH v6 03/12] mm/sparsemem: Add helpers track active portions of a section at boot To: Dan Williams 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 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)); }