From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v3 hmm 11/12] mm/hmm: Remove confusing comment and logic from hmm_release Date: Wed, 19 Jun 2019 01:07:05 -0700 Message-ID: <20190619080705.GA5164@infradead.org> References: <20190614004450.20252-1-jgg@ziepe.ca> <20190614004450.20252-12-jgg@ziepe.ca> <20190615142106.GK17724@infradead.org> <20190618004509.GE30762@ziepe.ca> <20190618053733.GA25048@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Sender: "amd-gfx" To: "Kuehling, Felix" Cc: Andrea Arcangeli , "Yang, Philip" , Ralph Campbell , "linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , John Hubbard , "dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org" , Christoph Hellwig , Jason Gunthorpe , Jerome Glisse , "amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org" , Ben Skeggs T24gV2VkLCBKdW4gMTksIDIwMTkgYXQgMTI6NTM6NTVBTSArMDAwMCwgS3VlaGxpbmcsIEZlbGl4 IHdyb3RlOgo+IFRoaXMgY29kZSBpcyBkZXJpdmVkIGZyb20gb3VyIG9sZCBNTVUgbm90aWZpZXIg Y29kZS4gQmVmb3JlIEhNTSB3ZSB1c2VkIAo+IHRvIHJlZ2lzdGVyIGEgc2luZ2xlIE1NVSBub3Rp ZmllciBwZXIgbW1fc3RydWN0IGFuZCBsb29rIHVwIHZpcnR1YWwgCj4gYWRkcmVzcyByYW5nZXMg dGhhdCBoYWQgYmVlbiByZWdpc3RlcmVkIGZvciBtaXJyb3JpbmcgdmlhIGRyaXZlciBBUEkgCj4g Y2FsbHMuIFRoZSBpZGVhIHdhcyB0byByZXVzZSBhIHNpbmdsZSBNTVUgbm90aWZpZXIgZm9yIHRo ZSBsaWZlIHRpbWUgb2YgCj4gdGhlIHByb2Nlc3MuIEl0IHdvdWxkIHJlbWFpbiByZWdpc3RlcmVk IHVudGlsIHdlIGdvdCBhIG5vdGlmaWVyX3JlbGVhc2UuCj4gCj4gaG1tX21pcnJvciB0b29rIHRo ZSBwbGFjZSBvZiB0aGF0IHdoZW4gd2UgY29udmVydGVkIHRoZSBjb2RlIHRvIEhNTS4KPiAKPiBJ IHN1cHBvc2Ugd2UgY291bGQgZGVzdHJveSB0aGUgbWlycm9yIGVhcmxpZXIsIHdoZW4gd2UgaGF2 ZSBubyBtb3JlIAo+IHJlZ2lzdGVyZWQgdmlydHVhbCBhZGRyZXNzIHJhbmdlcywgYW5kIGNyZWF0 ZSBhIG5ldyBvbmUgaWYgbmVlZGVkIGxhdGVyLgoKSSBkaWRuJ3Qgd3JpdGUgdGhlIGNvZGUsIGJ1 dCBpZiB5b3UgbG9vayBhdCBobW1fbWlycm9yIGl0IGFscmVhZHkgaXMKYSBtdWx0aXBsZXhlciBv dmVyIHRoZSBtbXUgbm90aWZpZXIsIGFuZCB0aGUgaW50ZW50IGNsZWFybHkgc2VlbXMgdGhhdAp5 b3UgcmVnaXN0ZXIgb25lIHBlciByYW5nZSB0aGF0IHlvdSB3YW50IHRvIG1pcnJvciwgYW5kIG5v dCBtdWx0aXBsZXgKaXQgb25jZSBhZ2Fpbi4gIEluIG90aGVyIHdvcmRzIC0gSSB0aGluayBlYWNo IGFtZGdwdV9tbl9ub2RlIHNob3VsZApwcm9iYWJseSBoYXZlIGl0cyBvd24gaG1tX21pcnJvci4g IEFuZCB3aGlsZSB0aGUgYW1kZ3B1X21uX25vZGUgb2JqZWN0cwphcmUgY3VycmVudGx5IHN0b3Jl ZCBpbiBhbiBpbnRlcnZhbCB0cmVlIGl0IHNlZW1zIGxpa2UgdGhleSBhcmUgb25seQpsaW5lYXJs eSBpdGVyYXRlZCBhbnl3YXksIHNvIGEgbGlzdCBhY3R1YWxseSBzZWVtcyBwcmV0dHkgc3VpdGFi bGUuICBJZgpub3Qgd2UgbmVlZCB0byBpbXByb3ZlIHRoZSBjb3JlIGRhdGEgc3RydWN0dXJlcyBp bnN0ZWFkIG9mIHdvcmtpbmcKYXJvdW5kIHRoZW0uCl9fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fCmFtZC1nZnggbWFpbGluZyBsaXN0CmFtZC1nZnhAbGlzdHMu ZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlz dGluZm8vYW1kLWdmeA== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39385C31E49 for ; 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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id o71si797514pjb.8.2019.06.19.01.07.08 for (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 19 Jun 2019 01:07:08 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of batv+77cd4ac56e5e79ab4dbe+5778+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=WdRlzSpz; spf=pass (google.com: best guess record for domain of batv+77cd4ac56e5e79ab4dbe+5778+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+77cd4ac56e5e79ab4dbe+5778+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=joSQX+c79LrXwDofUn4UcqKpzHato3fL9zTkPCCp5Mk=; b=WdRlzSpz2usjiHEXhhtXkURap JR/ywCqFnns9c9y2t4j4VowNJXeRydRRNboQlVSHN8bq2ehggKbdZH1HlMzQMHyezwSB+PRDQklSm QGdvWLYUFZn9VrVTSA3XepaQVYpa+5bgROMB9yzWCXXaKy+/WJuY+VzMSw9v59/fKxlT2CobF5aT/ iKwPEhqNC+F/eV+jAM/BxqQZIwJr5YGZ/rjVwaXAmRH+b9vNvmm3V2rDsAcKr5ORPlRjhxXjkKPPx 3nWz74yeA+o4L5ZKbl6tDC67LBLtYr13ByiHJ3KK4La27WSvZ17+VriT5N6Bx7Ur9bTQVNY8zxBGU CLLHoGCOg==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hdVcX-00045B-4O; Wed, 19 Jun 2019 08:07:05 +0000 Date: Wed, 19 Jun 2019 01:07:05 -0700 From: Christoph Hellwig To: "Kuehling, Felix" Cc: Christoph Hellwig , Jason Gunthorpe , Jerome Glisse , Ralph Campbell , John Hubbard , "linux-rdma@vger.kernel.org" , "linux-mm@kvack.org" , Andrea Arcangeli , "dri-devel@lists.freedesktop.org" , "amd-gfx@lists.freedesktop.org" , Ben Skeggs , "Yang, Philip" Subject: Re: [PATCH v3 hmm 11/12] mm/hmm: Remove confusing comment and logic from hmm_release Message-ID: <20190619080705.GA5164@infradead.org> References: <20190614004450.20252-1-jgg@ziepe.ca> <20190614004450.20252-12-jgg@ziepe.ca> <20190615142106.GK17724@infradead.org> <20190618004509.GE30762@ziepe.ca> <20190618053733.GA25048@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jun 19, 2019 at 12:53:55AM +0000, Kuehling, Felix wrote: > This code is derived from our old MMU notifier code. Before HMM we used > to register a single MMU notifier per mm_struct and look up virtual > address ranges that had been registered for mirroring via driver API > calls. The idea was to reuse a single MMU notifier for the life time of > the process. It would remain registered until we got a notifier_release. > > hmm_mirror took the place of that when we converted the code to HMM. > > I suppose we could destroy the mirror earlier, when we have no more > registered virtual address ranges, and create a new one if needed later. I didn't write the code, but if you look at hmm_mirror it already is a multiplexer over the mmu notifier, and the intent clearly seems that you register one per range that you want to mirror, and not multiplex it once again. In other words - I think each amdgpu_mn_node should probably have its own hmm_mirror. And while the amdgpu_mn_node objects are currently stored in an interval tree it seems like they are only linearly iterated anyway, so a list actually seems pretty suitable. If not we need to improve the core data structures instead of working around them.