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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 B1789C43141 for ; Fri, 15 Nov 2019 21:13:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94BAB2073B for ; Fri, 15 Nov 2019 21:13:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727427AbfKOVN1 (ORCPT ); Fri, 15 Nov 2019 16:13:27 -0500 Received: from smtprelay0097.hostedemail.com ([216.40.44.97]:45045 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727414AbfKOVNZ (ORCPT ); Fri, 15 Nov 2019 16:13:25 -0500 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay04.hostedemail.com (Postfix) with ESMTP id 4CEEF1800972C; Fri, 15 Nov 2019 21:13:24 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: sheet88_3ab5708df5b0a X-Filterd-Recvd-Size: 1924 Received: from XPS-9350.home (unknown [47.151.135.224]) (Authenticated sender: joe@perches.com) by omf01.hostedemail.com (Postfix) with ESMTPA; Fri, 15 Nov 2019 21:13:23 +0000 (UTC) Message-ID: Subject: Re: [PATCH] iommu/iova: silence warnings under memory pressure From: Joe Perches To: Qian Cai , jroedel@suse.de Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Date: Fri, 15 Nov 2019 13:13:03 -0800 In-Reply-To: <1573851046-32384-1-git-send-email-cai@lca.pw> References: <1573851046-32384-1-git-send-email-cai@lca.pw> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.34.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2019-11-15 at 15:50 -0500, Qian Cai wrote: > When running heavy memory pressure workloads, this 5+ old system is > throwing endless warnings below because disk IO is too slow to recover > from swapping. Since the volume from alloc_iova_fast() could be large, > once it calls printk(), it will trigger disk IO (writing to the log > files) and pending softirqs which could cause a loop and no progress > from memory reclaim for days. [] > diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c [] > @@ -233,7 +233,7 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, > > struct iova *alloc_iova_mem(void) > { > - return kmem_cache_alloc(iova_cache, GFP_ATOMIC); > + return kmem_cache_alloc(iova_cache, GFP_ATOMIC | __GFP_NOWARN); > } > EXPORT_SYMBOL(alloc_iova_mem); Is notification ever useful? If so, maybe something like: struct iova *alloc_iova_mem(void) { void *mem = kmem_cache_alloc(iova_cache, GFP_ATOMIC | __GFP_NOWARN)_ WARN_RATELIMIT(!mem, "%s: unable to alloc cache\n", __func__); return mem; } or maybe use printk_deferred or prink_deferred_once ?