From patchwork Thu Mar 21 01:39:52 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herbert Xu X-Patchwork-Id: 1059709 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=gondor.apana.org.au Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 44PqGt6Phsz9sRD for ; Thu, 21 Mar 2019 12:40:06 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727751AbfCUBkC (ORCPT ); Wed, 20 Mar 2019 21:40:02 -0400 Received: from orcrist.hmeau.com ([104.223.48.154]:57376 "EHLO deadmen.hmeau.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726487AbfCUBkB (ORCPT ); Wed, 20 Mar 2019 21:40:01 -0400 Received: from gondobar.mordor.me.apana.org.au ([192.168.128.4] helo=gondobar) by deadmen.hmeau.com with esmtps (Exim 4.89 #2 (Debian)) id 1h6mgW-0006YX-FV; Thu, 21 Mar 2019 09:39:56 +0800 Received: from herbert by gondobar with local (Exim 4.89) (envelope-from ) id 1h6mgS-0002cR-7D; Thu, 21 Mar 2019 09:39:52 +0800 Date: Thu, 21 Mar 2019 09:39:52 +0800 From: Herbert Xu To: Josh Hunt Cc: Josh Elsasser , "David S . Miller" , Thomas Graf , netdev , LKML Subject: [v3 PATCH] rhashtable: Still do rehash when we get EEXIST Message-ID: <20190321013952.3quw6bsqptyngzo5@gondor.apana.org.au> References: <20190123211758.104275-1-jelsasser@appneta.com> <20190124030841.n4jtsqka5zji3e62@gondor.apana.org.au> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Mar 20, 2019 at 03:29:17PM -0700, Josh Hunt wrote: > > Herbert > > We're seeing this pretty regularly on 4.14 LTS kernels. I didn't see your > change in any of the regular trees. Are there plans to submit this? If so, > can it get queued up for 4.14 stable too? Hi Josh: Thanks for reminding me. Looks like this one slipped through the cracks. Dave, could you please apply this? Thanks! ---8<--- As it stands if a shrink is delayed because of an outstanding rehash, we will go into a rescheduling loop without ever doing the rehash. This patch fixes this by still carrying out the rehash and then rescheduling so that we can shrink after the completion of the rehash should it still be necessary. The return value of EEXIST captures this case and other cases (e.g., another thread expanded/rehashed the table at the same time) where we should still proceed with the rehash. Fixes: da20420f83ea ("rhashtable: Add nested tables") Reported-by: Josh Elsasser Signed-off-by: Herbert Xu Tested-by: Josh Elsasser diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 852ffa5160f1..4edcf3310513 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -416,8 +416,12 @@ static void rht_deferred_worker(struct work_struct *work) else if (tbl->nest) err = rhashtable_rehash_alloc(ht, tbl, tbl->size); - if (!err) - err = rhashtable_rehash_table(ht); + if (!err || err == -EEXIST) { + int nerr; + + nerr = rhashtable_rehash_table(ht); + err = err ?: nerr; + } mutex_unlock(&ht->mutex);