On Wed 16-10-19 13:04:53, Anshuman Khandual wrote: > HugeTLB helper alloc_gigantic_page() implements fairly generic allocation > method where it scans over various zones looking for a large contiguous pfn > range before trying to allocate it with alloc_contig_range(). Other than > deriving the requested order from 'struct hstate', there is nothing HugeTLB > specific in there. This can be made available for general use to allocate > contiguous memory which could not have been allocated through the buddy > allocator. > > alloc_gigantic_page() has been split carving out actual allocation method > which is then made available via new alloc_contig_pages() helper wrapped > under CONFIG_CONTIG_ALLOC. All references to 'gigantic' have been replaced > with more generic term 'contig'. Allocated pages here should be freed with > free_contig_range() or by calling __free_page() on each allocated page.
Do we want to export this to modules? Apart from mostly styling issues pointed by David this looks fine. I do agree that a general allocator api belongs to page_alloc.c rather than force people to invent their own and broken instances. > Cc: Mike Kravetz <mike.krav...@oracle.com> > Cc: Andrew Morton <a...@linux-foundation.org> > Cc: Vlastimil Babka <vba...@suse.cz> > Cc: Michal Hocko <mho...@suse.com> > Cc: David Rientjes <rient...@google.com> > Cc: Andrea Arcangeli <aarca...@redhat.com> > Cc: Oscar Salvador <osalva...@suse.de> > Cc: Mel Gorman <mgor...@techsingularity.net> > Cc: Mike Rapoport <r...@linux.ibm.com> > Cc: Dan Williams <dan.j.willi...@intel.com> > Cc: Pavel Tatashin <pavel.tatas...@microsoft.com> > Cc: Matthew Wilcox <wi...@infradead.org> > Cc: David Hildenbrand <da...@redhat.com> > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual <anshuman.khand...@arm.com> After other issues mentioned by David get resolved you can add Acked-by: Michal Hocko <mho...@suse.com> > --- > This is based on https://patchwork.kernel.org/patch/11190213/ > > Changes from [V5,1/2] mm/hugetlb: Make alloc_gigantic_page()... > > - alloc_contig_page() takes nr_pages instead of order per Michal > - s/gigantic/contig on all related functions > > include/linux/gfp.h | 2 + > mm/hugetlb.c | 77 +---------------------------------- > mm/page_alloc.c | 97 +++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 101 insertions(+), 75 deletions(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index fb07b503dc45..1a11d4857027 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -589,6 +589,8 @@ static inline bool pm_suspended_storage(void) > /* The below functions must be run on a range from a single zone. */ > extern int alloc_contig_range(unsigned long start, unsigned long end, > unsigned migratetype, gfp_t gfp_mask); > +extern struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t > gfp_mask, > + int nid, nodemask_t *nodemask); > #endif > void free_contig_range(unsigned long pfn, unsigned int nr_pages); > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 985ee15eb04b..a5c2c880af27 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1023,85 +1023,12 @@ static void free_gigantic_page(struct page *page, > unsigned int order) > } > > #ifdef CONFIG_CONTIG_ALLOC > -static int __alloc_gigantic_page(unsigned long start_pfn, > - unsigned long nr_pages, gfp_t gfp_mask) > -{ > - unsigned long end_pfn = start_pfn + nr_pages; > - return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE, > - gfp_mask); > -} > - > -static bool pfn_range_valid_gigantic(struct zone *z, > - unsigned long start_pfn, unsigned long nr_pages) > -{ > - unsigned long i, end_pfn = start_pfn + nr_pages; > - struct page *page; > - > - for (i = start_pfn; i < end_pfn; i++) { > - page = pfn_to_online_page(i); > - if (!page) > - return false; > - > - if (page_zone(page) != z) > - return false; > - > - if (PageReserved(page)) > - return false; > - > - if (page_count(page) > 0) > - return false; > - > - if (PageHuge(page)) > - return false; > - } > - > - return true; > -} > - > -static bool zone_spans_last_pfn(const struct zone *zone, > - unsigned long start_pfn, unsigned long nr_pages) > -{ > - unsigned long last_pfn = start_pfn + nr_pages - 1; > - return zone_spans_pfn(zone, last_pfn); > -} > - > static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask, > int nid, nodemask_t *nodemask) > { > - unsigned int order = huge_page_order(h); > - unsigned long nr_pages = 1 << order; > - unsigned long ret, pfn, flags; > - struct zonelist *zonelist; > - struct zone *zone; > - struct zoneref *z; > - > - zonelist = node_zonelist(nid, gfp_mask); > - for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), > nodemask) { > - spin_lock_irqsave(&zone->lock, flags); > + unsigned long nr_pages = 1UL << huge_page_order(h); > > - pfn = ALIGN(zone->zone_start_pfn, nr_pages); > - while (zone_spans_last_pfn(zone, pfn, nr_pages)) { > - if (pfn_range_valid_gigantic(zone, pfn, nr_pages)) { > - /* > - * We release the zone lock here because > - * alloc_contig_range() will also lock the zone > - * at some point. If there's an allocation > - * spinning on this lock, it may win the race > - * and cause alloc_contig_range() to fail... > - */ > - spin_unlock_irqrestore(&zone->lock, flags); > - ret = __alloc_gigantic_page(pfn, nr_pages, > gfp_mask); > - if (!ret) > - return pfn_to_page(pfn); > - spin_lock_irqsave(&zone->lock, flags); > - } > - pfn += nr_pages; > - } > - > - spin_unlock_irqrestore(&zone->lock, flags); > - } > - > - return NULL; > + return alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask); > } > > static void prep_new_huge_page(struct hstate *h, struct page *page, int nid); > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index cd1dd0712624..1e084d6acf2f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8499,6 +8499,103 @@ int alloc_contig_range(unsigned long start, unsigned > long end, > pfn_max_align_up(end), migratetype); > return ret; > } > + > +static int __alloc_contig_pages(unsigned long start_pfn, > + unsigned long nr_pages, gfp_t gfp_mask) > +{ > + unsigned long end_pfn = start_pfn + nr_pages; > + > + return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE, > + gfp_mask); > +} > + > +static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn, > + unsigned long nr_pages) > +{ > + unsigned long i, end_pfn = start_pfn + nr_pages; > + struct page *page; > + > + for (i = start_pfn; i < end_pfn; i++) { > + page = pfn_to_online_page(i); > + if (!page) > + return false; > + > + if (page_zone(page) != z) > + return false; > + > + if (PageReserved(page)) > + return false; > + > + if (page_count(page) > 0) > + return false; > + > + if (PageHuge(page)) > + return false; > + } > + return true; > +} > + > +static bool zone_spans_last_pfn(const struct zone *zone, > + unsigned long start_pfn, unsigned long nr_pages) > +{ > + unsigned long last_pfn = start_pfn + nr_pages - 1; > + > + return zone_spans_pfn(zone, last_pfn); > +} > + > +/** > + * alloc_contig_pages() -- tries to find and allocate contiguous range of > pages > + * @nr_pages: Number of contiguous pages to allocate > + * @gfp_mask: GFP mask to limit search and used during compaction > + * @nid: Target node > + * @nodemask: Mask for other possible nodes > + * > + * This routine is an wrapper around alloc_contig_range(). It scans over > zones > + * on an applicable zonelist to find a contiguous pfn range which can then be > + * tried for allocation with alloc_contig_range(). This routine is intended > + * for allocation requests which can not be fulfilled with buddy allocator. > + * > + * Allocated pages can be freed with free_contig_range() or by manually > calling > + * __free_page() on each allocated page. > + * > + * Return: pointer to 'order' pages on success, or NULL if not successful. > + */ > +struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask, > + int nid, nodemask_t *nodemask) > +{ > + unsigned long ret, pfn, flags; > + struct zonelist *zonelist; > + struct zone *zone; > + struct zoneref *z; > + > + zonelist = node_zonelist(nid, gfp_mask); > + for_each_zone_zonelist_nodemask(zone, z, zonelist, > + gfp_zone(gfp_mask), nodemask) { > + spin_lock_irqsave(&zone->lock, flags); > + > + pfn = ALIGN(zone->zone_start_pfn, nr_pages); > + while (zone_spans_last_pfn(zone, pfn, nr_pages)) { > + if (pfn_range_valid_contig(zone, pfn, nr_pages)) { > + /* > + * We release the zone lock here because > + * alloc_contig_range() will also lock the zone > + * at some point. If there's an allocation > + * spinning on this lock, it may win the race > + * and cause alloc_contig_range() to fail... > + */ > + spin_unlock_irqrestore(&zone->lock, flags); > + ret = __alloc_contig_pages(pfn, nr_pages, > + gfp_mask); > + if (!ret) > + return pfn_to_page(pfn); > + spin_lock_irqsave(&zone->lock, flags); > + } > + pfn += nr_pages; > + } > + spin_unlock_irqrestore(&zone->lock, flags); > + } > + return NULL; > +} > #endif /* CONFIG_CONTIG_ALLOC */ > > void free_contig_range(unsigned long pfn, unsigned int nr_pages) > -- > 2.20.1 -- Michal Hocko SUSE Labs
