On Sat, May 4, 2019, 3:26 PM Dan Williams <[email protected]> wrote:
> On Thu, May 2, 2019 at 9:12 AM Pavel Tatashin <[email protected]> > wrote: > > > > On Wed, Apr 17, 2019 at 2:53 PM Dan Williams <[email protected]> > 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 <[email protected]> > > > Cc: Vlastimil Babka <[email protected]> > > > Cc: Logan Gunthorpe <[email protected]> > > > Signed-off-by: Dan Williams <[email protected]> > > > --- > > > 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. > Yes, bitmap_* will help, and I assume you will also make active_map size scalable? I will take another look at version 8. Thank you, Pasha _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
