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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 922AAC433FE for ; Fri, 4 Mar 2022 09:42:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239515AbiCDJnU (ORCPT ); Fri, 4 Mar 2022 04:43:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239303AbiCDJmX (ORCPT ); Fri, 4 Mar 2022 04:42:23 -0500 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A97D18C799 for ; Fri, 4 Mar 2022 01:41:35 -0800 (PST) Received: by theia.8bytes.org (Postfix, from userid 1000) id 4DEE39BF; Fri, 4 Mar 2022 10:41:32 +0100 (CET) Date: Fri, 4 Mar 2022 10:41:31 +0100 From: Joerg Roedel To: Miles Chen Cc: robin.murphy@arm.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, will@kernel.org, wsd_upstream@mediatek.com, yf.wang@mediatek.com, stable@vger.kernel.org Subject: Re: [PATCH] iommu/iova: Improve 32-bit free space estimate Message-ID: References: <033815732d83ca73b13c11485ac39336f15c3b40.1646318408.git.robin.murphy@arm.com> <20220303233646.13773-1-miles.chen@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220303233646.13773-1-miles.chen@mediatek.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, Mar 04, 2022 at 07:36:46AM +0800, Miles Chen wrote: > Hi Robin, > > > For various reasons based on the allocator behaviour and typical > > use-cases at the time, when the max32_alloc_size optimisation was > > introduced it seemed reasonable to couple the reset of the tracked > > size to the update of cached32_node upon freeing a relevant IOVA. > > However, since subsequent optimisations focused on helping genuine > > 32-bit devices make best use of even more limited address spaces, it > > is now a lot more likely for cached32_node to be anywhere in a "full" > > 32-bit address space, and as such more likely for space to become > > available from IOVAs below that node being freed. > > > > At this point, the short-cut in __cached_rbnode_delete_update() really > > doesn't hold up any more, and we need to fix the logic to reliably > > provide the expected behaviour. We still want cached32_node to only move > > upwards, but we should reset the allocation size if *any* 32-bit space > > has become available. > > > > Reported-by: Yunfei Wang > > Signed-off-by: Robin Murphy > > Would you mind adding: > > Cc: Applied without stable tag for now. If needed, please consider re-sending it for stable when this patch is merged upstream. Regards, Joerg