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 9D798C433F5 for ; Fri, 4 Mar 2022 14:03:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239483AbiCDOEO (ORCPT ); Fri, 4 Mar 2022 09:04:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239756AbiCDOEN (ORCPT ); Fri, 4 Mar 2022 09:04:13 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AF6A8532D8; Fri, 4 Mar 2022 06:03:25 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7893E1424; Fri, 4 Mar 2022 06:03:25 -0800 (PST) Received: from [10.57.39.47] (unknown [10.57.39.47]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A7E423F70D; Fri, 4 Mar 2022 06:03:23 -0800 (PST) Message-ID: <906a446e-3e25-5813-d380-de699a84b6f4@arm.com> Date: Fri, 4 Mar 2022 14:03:22 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [PATCH] iommu/iova: Free all CPU rcache for retry when iova alloc failure Content-Language: en-GB To: yf.wang@mediatek.com, Joerg Roedel , Will Deacon , Matthias Brugger , "open list:IOMMU DRIVERS" , open list , "moderated list:ARM/Mediatek SoC support" , "moderated list:ARM/Mediatek SoC support" Cc: wsd_upstream@mediatek.com, Libo Kang , stable@vger.kernel.org, Ning Li References: <20220304044635.4273-1-yf.wang@mediatek.com> From: Robin Murphy In-Reply-To: <20220304044635.4273-1-yf.wang@mediatek.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 2022-03-04 04:46, yf.wang--- via iommu wrote: > From: Yunfei Wang > > In alloc_iova_fast function, if an iova alloc request fail, > it will free the iova ranges present in the percpu iova > rcaches and free global iova rcache and then retry, but > flushing CPU iova rcaches only for each online CPU, which > will cause incomplete rcache cleaning, and iova rcaches of > not online CPU cannot be flushed, because iova rcaches may > also lead to fragmentation of iova space, so the next retry > action may still be fail. > > Based on the above, so need to flushing all iova rcaches > for each possible CPU, use for_each_possible_cpu instead of > for_each_online_cpu like in free_iova_rcaches function, > so that all rcaches can be completely released to try > replenishing IOVAs. OK, so either there's a mystery bug where IOVAs somehow get freed on offline CPUs, or the hotplug notifier isn't working correctly, or you've contrived a situation where alloc_iova_fast() is actually racing against iova_cpuhp_dead(). In the latter case, the solution is "don't do that". This change should not be necessary. Thanks, Robin. > Signed-off-by: Yunfei Wang > Cc: # 5.4.* > --- > drivers/iommu/iova.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c > index b28c9435b898..5a0637cd7bc2 100644 > --- a/drivers/iommu/iova.c > +++ b/drivers/iommu/iova.c > @@ -460,7 +460,7 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size, > > /* Try replenishing IOVAs by flushing rcache. */ > flush_rcache = false; > - for_each_online_cpu(cpu) > + for_each_possible_cpu(cpu) > free_cpu_cached_iovas(cpu, iovad); > free_global_cached_iovas(iovad); > goto retry; > > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu