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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 1F82FC0044D for ; Mon, 16 Mar 2020 13:06:58 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E8654205ED for ; Mon, 16 Mar 2020 13:06:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E8654205ED Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=amd-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 85BCE89D2F; Mon, 16 Mar 2020 13:06:57 +0000 (UTC) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by gabe.freedesktop.org (Postfix) with ESMTPS id 11BE76E397 for ; Mon, 16 Mar 2020 09:08:05 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 02BB668CF0; Mon, 16 Mar 2020 10:02:51 +0100 (CET) Date: Mon, 16 Mar 2020 10:02:50 +0100 From: Christoph Hellwig To: Jason Gunthorpe Subject: Re: [PATCH hmm 2/8] mm/hmm: don't free the cached pgmap while scanning Message-ID: <20200316090250.GB12439@lst.de> References: <20200311183506.3997-1-jgg@ziepe.ca> <20200311183506.3997-3-jgg@ziepe.ca> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200311183506.3997-3-jgg@ziepe.ca> User-Agent: Mutt/1.5.17 (2007-11-01) X-Mailman-Approved-At: Mon, 16 Mar 2020 13:06:57 +0000 X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Philip Yang , Ralph Campbell , John Hubbard , Felix.Kuehling@amd.com, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Jerome Glisse , Jason Gunthorpe , amd-gfx@lists.freedesktop.org, Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" On Wed, Mar 11, 2020 at 03:35:00PM -0300, Jason Gunthorpe wrote: > @@ -694,6 +672,15 @@ long hmm_range_fault(struct hmm_range *range, unsigned int flags) > return -EBUSY; > ret = walk_page_range(mm, hmm_vma_walk.last, range->end, > &hmm_walk_ops, &hmm_vma_walk); > + /* > + * A pgmap is kept cached in the hmm_vma_walk to avoid expensive > + * searching in the probably common case that the pgmap is the > + * same for the entire requested range. > + */ > + if (hmm_vma_walk.pgmap) { > + put_dev_pagemap(hmm_vma_walk.pgmap); > + hmm_vma_walk.pgmap = NULL; > + } > } while (ret == -EBUSY); In which case it should only be put on return, and not for every loop. I still think the right fix is to just delete all the unused and broken pgmap handling code. If we ever need to add it back it can be added in a proper understood and tested way. _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx