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Sat, 21 Apr 2018 19:15:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:46354 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753272AbeDUXP2 (ORCPT ); Sat, 21 Apr 2018 19:15:28 -0400 From: Vlastimil Babka Subject: [PATCH 2/3] mm: add find_alloc_contig_pages() interface To: Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Cc: Reinette Chatre , Michal Hocko , Christopher Lameter , Guy Shattah , Anshuman Khandual , Michal Nazarewicz , David Nellans , Laura Abbott , Pavel Machek , Dave Hansen , Andrew Morton References: <20180417020915.11786-1-mike.kravetz@oracle.com> <20180417020915.11786-3-mike.kravetz@oracle.com> Message-ID: Date: Sat, 21 Apr 2018 18:16:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180417020915.11786-3-mike.kravetz@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 04/17/2018 04:09 AM, Mike Kravetz wrote: > find_alloc_contig_pages() is a new interface that attempts to locate > and allocate a contiguous range of pages. It is provided as a more > convenient interface than alloc_contig_range() which is currently > used by CMA and gigantic huge pages. > > When attempting to allocate a range of pages, migration is employed > if possible. There is no guarantee that the routine will succeed. > So, the user must be prepared for failure and have a fall back plan. > > Signed-off-by: Mike Kravetz Hi, just two quick observations, maybe discussion pointers for the LSF/MM session: - it's weird that find_alloc_contig_pages() takes an order, and free_contig_pages() takes a nr_pages. I suspect the interface would be more future-proof with both using nr_pages? Perhaps also minimum alignment for the allocation side? Order is fine for hugetlb, but what about other potential users? - contig_alloc_migratetype_ok() says that MIGRATE_CMA blocks are OK to allocate from. This silently assumes that everything allocated by this will be migratable itself, or it might eat CMA reserves. Is it the case? Also you then call alloc_contig_range() with MIGRATE_MOVABLE, so it will skip/fail on MIGRATE_CMA anyway IIRC. Vlastimil > --- > include/linux/gfp.h | 12 ++++++++ > mm/page_alloc.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 99 insertions(+), 2 deletions(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 86a0d06463ab..528b194cc266 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -573,6 +573,18 @@ static inline bool pm_suspended_storage(void) > extern int alloc_contig_range(unsigned long start, unsigned long end, > unsigned migratetype, gfp_t gfp_mask); > extern void free_contig_range(unsigned long pfn, unsigned long nr_pages); > +extern struct page *find_alloc_contig_pages(unsigned int order, gfp_t gfp, > + int nid, nodemask_t *nodemask); > +extern void free_contig_pages(struct page *page, unsigned long nr_pages); > +#else > +static inline page *find_alloc_contig_pages(unsigned int order, gfp_t gfp, > + int nid, nodemask_t *nodemask) > +{ > + return NULL; > +} > +static void free_contig_pages(struct page *page, unsigned long nr_pages) > +{ > +} > #endif > > #ifdef CONFIG_CMA > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 0fd5e8e2456e..81070fe55c44 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -67,6 +67,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -2010,9 +2011,13 @@ static __always_inline struct page *__rmqueue_cma_fallback(struct zone *zone, > { > return __rmqueue_smallest(zone, order, MIGRATE_CMA); > } > +#define contig_alloc_migratetype_ok(migratetype) \ > + ((migratetype) == MIGRATE_CMA || (migratetype) == MIGRATE_MOVABLE) > #else > static inline struct page *__rmqueue_cma_fallback(struct zone *zone, > unsigned int order) { return NULL; } > +#define contig_alloc_migratetype_ok(migratetype) \ > + ((migratetype) == MIGRATE_MOVABLE) > #endif > > /* > @@ -7822,6 +7827,9 @@ int alloc_contig_range(unsigned long start, unsigned long end, > }; > INIT_LIST_HEAD(&cc.migratepages); > > + if (!contig_alloc_migratetype_ok(migratetype)) > + return -EINVAL; > + > /* > * What we do here is we mark all pageblocks in range as > * MIGRATE_ISOLATE. Because pageblock and max order pages may > @@ -7912,8 +7920,9 @@ int alloc_contig_range(unsigned long start, unsigned long end, > > /* Make sure the range is really isolated. */ > if (test_pages_isolated(outer_start, end, false)) { > - pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n", > - __func__, outer_start, end); > + if (!(migratetype == MIGRATE_MOVABLE)) /* only print for CMA */ > + pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n", > + __func__, outer_start, end); > ret = -EBUSY; > goto done; > } > @@ -7949,6 +7958,82 @@ void free_contig_range(unsigned long pfn, unsigned long nr_pages) > } > WARN(count != 0, "%ld pages are still in use!\n", count); > } > + > +static bool contig_pfn_range_valid(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++) { > + if (!pfn_valid(i)) > + return false; > + > + page = pfn_to_page(i); > + > + if (page_zone(page) != z) > + return false; > + > + } > + > + return true; > +} > + > +/** > + * find_alloc_contig_pages() -- attempt to find and allocate a contiguous > + * range of pages > + * @order: number of pages > + * @gfp: gfp mask used to limit search as well as during compaction > + * @nid: target node > + * @nodemask: mask of other possible nodes > + * > + * Pages can be freed with a call to free_contig_pages(), or by manually > + * calling __free_page() for each page allocated. > + * > + * Return: pointer to 'order' pages on success, or NULL if not successful. > + */ > +struct page *find_alloc_contig_pages(unsigned int order, gfp_t gfp, > + int nid, nodemask_t *nodemask) > +{ > + unsigned long pfn, nr_pages, flags; > + struct page *ret_page = NULL; > + struct zonelist *zonelist; > + struct zoneref *z; > + struct zone *zone; > + int rc; > + > + nr_pages = 1 << order; > + zonelist = node_zonelist(nid, gfp); > + for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp), > + nodemask) { > + spin_lock_irqsave(&zone->lock, flags); > + pfn = ALIGN(zone->zone_start_pfn, nr_pages); > + while (zone_spans_pfn(zone, pfn + nr_pages - 1)) { > + if (contig_pfn_range_valid(zone, pfn, nr_pages)) { > + spin_unlock_irqrestore(&zone->lock, flags); > + > + rc = alloc_contig_range(pfn, pfn + nr_pages, > + MIGRATE_MOVABLE, gfp); > + if (!rc) { > + ret_page = pfn_to_page(pfn); > + return ret_page; > + } > + spin_lock_irqsave(&zone->lock, flags); > + } > + pfn += nr_pages; > + } > + spin_unlock_irqrestore(&zone->lock, flags); > + } > + > + return ret_page; > +} > +EXPORT_SYMBOL_GPL(find_alloc_contig_pages); > + > +void free_contig_pages(struct page *page, unsigned long nr_pages) > +{ > + free_contig_range(page_to_pfn(page), nr_pages); > +} > +EXPORT_SYMBOL_GPL(free_contig_pages); > #endif > > #if defined CONFIG_MEMORY_HOTPLUG || defined CONFIG_CMA >