From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v3 hmm 06/12] mm/hmm: Hold on to the mmget for the lifetime of the range Date: Sat, 15 Jun 2019 07:14:35 -0700 Message-ID: <20190615141435.GF17724@infradead.org> References: <20190614004450.20252-1-jgg@ziepe.ca> <20190614004450.20252-7-jgg@ziepe.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <20190614004450.20252-7-jgg-uk2M96/98Pc@public.gmane.org> 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: Jason Gunthorpe Cc: Andrea Arcangeli , Philip Yang , Ralph Campbell , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, John Hubbard , Felix.Kuehling-5C7GfCeVMHo@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Jerome Glisse , Jason Gunthorpe , amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, Ben Skeggs PiAgCW11dGV4X2xvY2soJmhtbS0+bG9jayk7Cj4gLQlsaXN0X2Zvcl9lYWNoX2VudHJ5KHJhbmdl LCAmaG1tLT5yYW5nZXMsIGxpc3QpCj4gLQkJcmFuZ2UtPnZhbGlkID0gZmFsc2U7Cj4gLQl3YWtl X3VwX2FsbCgmaG1tLT53cSk7Cj4gKwkvKgo+ICsJICogU2luY2UgaG1tX3JhbmdlX3JlZ2lzdGVy KCkgaG9sZHMgdGhlIG1tZ2V0KCkgbG9jayBobW1fcmVsZWFzZSgpIGlzCj4gKwkgKiBwcmV2ZW50 ZWQgYXMgbG9uZyBhcyBhIHJhbmdlIGV4aXN0cy4KPiArCSAqLwo+ICsJV0FSTl9PTighbGlzdF9l bXB0eSgmaG1tLT5yYW5nZXMpKTsKPiAgCW11dGV4X3VubG9jaygmaG1tLT5sb2NrKTsKClRoaXMg Y2FuIGp1c3QgdXNlIGxpc3RfZW1wdHlfY2FyZWZ1bCBhbmQgYXZvaWQgdGhlIGxvY2sgZW50aXJl bHkuCgpPdGhlcndpc2UgbG9va3MgZ29vZDoKClJldmlld2VkLWJ5OiBDaHJpc3RvcGggSGVsbHdp ZyA8aGNoQGxzdC5kZT4KX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX18KYW1kLWdmeCBtYWlsaW5nIGxpc3QKYW1kLWdmeEBsaXN0cy5mcmVlZGVza3RvcC5vcmcK aHR0cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9hbWQtZ2Z4 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, URIBL_BLOCKED,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 84925C31E50 for ; 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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id 194si5571437pga.203.2019.06.15.07.14.38 for (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sat, 15 Jun 2019 07:14:38 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of batv+78a6abdb7ec5759febfc+5774+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=NDaar3aY; spf=pass (google.com: best guess record for domain of batv+78a6abdb7ec5759febfc+5774+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+78a6abdb7ec5759febfc+5774+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=6K3IZWimfXFDx5zlj0FydVfqj2gXTabKUZsGz9eiwgw=; b=NDaar3aYYUTqIadeUzt3fjl5e xTvini6vXAxFVVQTpQjC/ZVFmzryOfabxlaFlyZA9bhVT+06royjNgkE6cNob+/+Zo0FZs6bvV6i2 VV99tEpby1InU8VhqJHXDCu8OrpmNPZf177PEPtOvB64PS4aPV7XjPvCz0pCp9kzA00pOYzzGBUDW GenFaGRR1yzUlw7nCrOkq+FP9YqBtZNwe1bMN2gEUOqCCy6Na/j6nAQDBCzPKIOyZbbXEwoKCXER8 g8r+0iep8vK1xgNwY+knre1ESI1PCehtG9SiyEQby/7Vugv6F9vqNXIS2/CraTZJ8jq/eDJjaRazX 3ehroctrA==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hc9Rz-0002Dl-UH; Sat, 15 Jun 2019 14:14:35 +0000 Date: Sat, 15 Jun 2019 07:14:35 -0700 From: Christoph Hellwig To: Jason Gunthorpe Cc: Jerome Glisse , Ralph Campbell , John Hubbard , Felix.Kuehling@amd.com, linux-rdma@vger.kernel.org, linux-mm@kvack.org, Andrea Arcangeli , dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, Ben Skeggs , Jason Gunthorpe , Philip Yang Subject: Re: [PATCH v3 hmm 06/12] mm/hmm: Hold on to the mmget for the lifetime of the range Message-ID: <20190615141435.GF17724@infradead.org> References: <20190614004450.20252-1-jgg@ziepe.ca> <20190614004450.20252-7-jgg@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190614004450.20252-7-jgg@ziepe.ca> 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: > mutex_lock(&hmm->lock); > - list_for_each_entry(range, &hmm->ranges, list) > - range->valid = false; > - wake_up_all(&hmm->wq); > + /* > + * Since hmm_range_register() holds the mmget() lock hmm_release() is > + * prevented as long as a range exists. > + */ > + WARN_ON(!list_empty(&hmm->ranges)); > mutex_unlock(&hmm->lock); This can just use list_empty_careful and avoid the lock entirely. Otherwise looks good: Reviewed-by: Christoph Hellwig