From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-6501-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id EC30E985DBA for ; Thu, 12 Dec 2019 17:12:42 +0000 (UTC) From: David Hildenbrand Date: Thu, 12 Dec 2019 18:11:28 +0100 Message-Id: <20191212171137.13872-5-david@redhat.com> In-Reply-To: <20191212171137.13872-1-david@redhat.com> References: <20191212171137.13872-1-david@redhat.com> MIME-Version: 1.0 Subject: [virtio-dev] [PATCH RFC v4 04/13] mm: Export alloc_contig_range() / free_contig_range() Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, Michal Hocko , Andrew Morton , "Michael S . Tsirkin" , David Hildenbrand , Michal Hocko , Vlastimil Babka , Oscar Salvador , Mel Gorman , Mike Rapoport , Dan Williams , Alexander Duyck , Pavel Tatashin , Alexander Potapenko List-ID: A virtio-mem device wants to allocate memory from the memory region it manages in order to unplug it in the hypervisor - similar to a balloon driver. Also, it might want to plug previously unplugged (allocated) memory and give it back to Linux. alloc_contig_range() / free_contig_range() seem to be the perfect interface for this task. In contrast to existing balloon devices, a virtio-mem device operates on bigger chunks (e.g., 4MB) and only on physical memory it manages. It tracks which chunks (subblocks) are still plugged, so it can go ahead and try to alloc_contig_range()+unplug them on unplug request, or plug+free_contig_range() unplugged chunks on plug requests. A virtio-mem device will use alloc_contig_range() / free_contig_range() only on ranges that belong to the same node/zone in at least MAX(MAX_ORDER - 1, pageblock_order) order granularity - e.g., 4MB on x86-64. The virtio-mem device added that memory, so the memory exists and does not contain any holes. virtio-mem will only try to allocate on ZONE_NORMAL, never on ZONE_MOVABLE, just like when allocating gigantic pages (we don't put unmovable data into the movable zone). Cc: Andrew Morton Cc: Michal Hocko Cc: Vlastimil Babka Cc: Oscar Salvador Cc: Mel Gorman Cc: Mike Rapoport Cc: Dan Williams Cc: Alexander Duyck Cc: Pavel Tatashin Cc: Alexander Potapenko Acked-by: Michal Hocko # to export contig range allocator= API Signed-off-by: David Hildenbrand --- mm/page_alloc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 62dcd6b76c80..5334decc9e06 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8494,6 +8494,7 @@ int alloc_contig_range(unsigned long start, unsigned = long end, =09=09=09=09pfn_max_align_up(end), migratetype); =09return ret; } +EXPORT_SYMBOL(alloc_contig_range); =20 static int __alloc_contig_pages(unsigned long start_pfn, =09=09=09=09unsigned long nr_pages, gfp_t gfp_mask) @@ -8609,6 +8610,7 @@ void free_contig_range(unsigned long pfn, unsigned in= t nr_pages) =09} =09WARN(count !=3D 0, "%d pages are still in use!\n", count); } +EXPORT_SYMBOL(free_contig_range); =20 /* * The zone indicated has a new number of managed_pages; batch sizes and p= ercpu --=20 2.23.0 --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org