From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id F07856B025E for ; Thu, 21 Dec 2017 07:14:45 -0500 (EST) Received: by mail-pl0-f69.google.com with SMTP id 33so11483595pll.9 for ; Thu, 21 Dec 2017 04:14:45 -0800 (PST) Received: from bombadil.infradead.org (bombadil.infradead.org. [65.50.211.133]) by mx.google.com with ESMTPS id x2si13361178pgr.500.2017.12.21.04.14.44 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 21 Dec 2017 04:14:44 -0800 (PST) Date: Thu, 21 Dec 2017 04:14:37 -0800 From: Matthew Wilcox Subject: Re: [PATCH v20 0/7] Virtio-balloon Enhancement Message-ID: <20171221121437.GA22405@bombadil.infradead.org> References: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com> <201712192305.AAE21882.MtQHJOFFSFVOLO@I-love.SAKURA.ne.jp> <5A3A3CBC.4030202@intel.com> <20171220122547.GA1654@bombadil.infradead.org> <286AC319A985734F985F78AFA26841F73938CC3E@shsmsx102.ccr.corp.intel.com> <20171220171019.GA12236@bombadil.infradead.org> <5A3B2148.8050306@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5A3B2148.8050306@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wei Wang Cc: Tetsuo Handa , "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" , "mhocko@kernel.org" , "akpm@linux-foundation.org" , "mawilcox@microsoft.com" , "david@redhat.com" , "cornelia.huck@de.ibm.com" , "mgorman@techsingularity.net" , "aarcange@redhat.com" , "amit.shah@redhat.com" , "pbonzini@redhat.com" , "liliang.opensource@gmail.com" , "yang.zhang.wz@gmail.com" , "quan.xu0@gmail.com" , "nilal@redhat.com" , "riel@redhat.com" On Thu, Dec 21, 2017 at 10:49:44AM +0800, Wei Wang wrote: > On 12/21/2017 01:10 AM, Matthew Wilcox wrote: > One more question is about the return value, why would it be ambiguous? I > think it is the same as find_next_bit() which returns the found bit or size > if not found. Because find_next_bit doesn't reasonably support a bitmap which is ULONG_MAX in size. The point of XBitmap is to support a bitmap which is ULONG_MAX in size, so every possible return value is a legitimate "we found a bit here". There's no value which can possibly be used for "no bit was found". -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org