From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Wang Subject: Re: [PATCH v9 3/5] mm: function to offer a page block on the free list Date: Fri, 14 Apr 2017 10:30:27 +0800 Message-ID: <58F03443.9040202@intel.com> References: <1492076108-117229-1-git-send-email-wei.w.wang@intel.com> <1492076108-117229-4-git-send-email-wei.w.wang@intel.com> <20170413130217.2316b0394192d8677f5ddbdf@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, david@redhat.com, dave.hansen@intel.com, cornelia.huck@de.ibm.com, mgorman@techsingularity.net, aarcange@redhat.com, amit.shah@redhat.com, pbonzini@redhat.com, liliang.opensource@gmail.com To: Andrew Morton Return-path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: In-Reply-To: <20170413130217.2316b0394192d8677f5ddbdf@linux-foundation.org> List-Id: kvm.vger.kernel.org On 04/14/2017 04:02 AM, Andrew Morton wrote: > On Thu, 13 Apr 2017 17:35:06 +0800 Wei Wang wrote: > >> Add a function to find a page block on the free list specified by the >> caller. Pages from the page block may be used immediately after the >> function returns. The caller is responsible for detecting or preventing >> the use of such pages. >> >> ... >> >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -4498,6 +4498,93 @@ void show_free_areas(unsigned int filter) >> show_swap_cache_info(); >> } >> >> +/** >> + * Heuristically get a page block in the system that is unused. >> + * It is possible that pages from the page block are used immediately after >> + * inquire_unused_page_block() returns. It is the caller's responsibility >> + * to either detect or prevent the use of such pages. >> + * >> + * The free list to check: zone->free_area[order].free_list[migratetype]. >> + * >> + * If the caller supplied page block (i.e. **page) is on the free list, offer >> + * the next page block on the list to the caller. Otherwise, offer the first >> + * page block on the list. >> + * >> + * Return 0 when a page block is found on the caller specified free list. >> + */ >> +int inquire_unused_page_block(struct zone *zone, unsigned int order, >> + unsigned int migratetype, struct page **page) >> +{ > Perhaps we can wrap this in the appropriate ifdef so the kernels which > won't be using virtio-balloon don't carry the added overhead. > > OK. What do you think if we add this: #if defined(CONFIG_VIRTIO_BALLOON) || defined(CONFIG_VIRTIO_BALLOON_MODULE) Best, Wei