From patchwork Thu Sep 17 08:10:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oscar Salvador X-Patchwork-Id: 11781963 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D456E618 for ; Thu, 17 Sep 2020 08:27:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8993E2083B for ; Thu, 17 Sep 2020 08:27:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8993E2083B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 76D986B0055; Thu, 17 Sep 2020 04:27:47 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 6F2BF6B005A; Thu, 17 Sep 2020 04:27:47 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5E1E36B005C; Thu, 17 Sep 2020 04:27:47 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0038.hostedemail.com [216.40.44.38]) by kanga.kvack.org (Postfix) with ESMTP id 449D86B0055 for ; Thu, 17 Sep 2020 04:27:47 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id EEFD78249980 for ; Thu, 17 Sep 2020 08:27:46 +0000 (UTC) X-FDA: 77271874932.02.cough26_2807aaf27121 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id BF08F100BEE39 for ; Thu, 17 Sep 2020 08:27:46 +0000 (UTC) X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,osalvador@suse.de,,RULES_HIT:30054,0,RBL:195.135.220.15:@suse.de:.lbl8.mailshell.net-62.2.6.2 64.100.201.201;04yfxbqaqkburu56fmn44kqkh7n8iyc7n47jk6jx7wncd9rop5o99ybwrzwhq5q.q6q3eu9apzybncqj1rdkfammkqhtx5mtg71dfwzeofwa1y8h4tkigx9bba6qc8n.1-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:24,LUA_SUMMARY:none X-HE-Tag: cough26_2807aaf27121 X-Filterd-Recvd-Size: 2515 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Thu, 17 Sep 2020 08:27:46 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2A772B134; Thu, 17 Sep 2020 08:28:18 +0000 (UTC) From: Oscar Salvador To: akpm@linux-foundation.org Cc: aris@ruivo.org, naoya.horiguchi@nec.com, mhocko@kernel.org, tony.luck@intel.com, cai@lca.pw, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Oscar Salvador Subject: [PATCH v4 3/7] mm,hwpoison: Try to narrow window race for free pages Date: Thu, 17 Sep 2020 10:10:45 +0200 Message-Id: <20200917081049.27428-4-osalvador@suse.de> X-Mailer: git-send-email 2.13.7 In-Reply-To: <20200917081049.27428-1-osalvador@suse.de> References: <20200917081049.27428-1-osalvador@suse.de> X-Rspamd-Queue-Id: BF08F100BEE39 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Aristeu Rozanski reported that a customer test case started to report -EBUSY after the hwpoison report patchset. There is a race window between spotting a free page and taking it off its buddy freelist, so it might be that by the time we try to take it off, the page has been already allocated. This patch tries to handle such race window by trying to handle the new type of page again if the page was allocated under us. After this patch, Aristeu said the test cases work properly. Signed-off-by: Oscar Salvador Reported-by: Aristeu Rozanski Tested-by: Aristeu Rozanski --- mm/memory-failure.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index db61bdee9734..a2ccd3ba4015 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1917,6 +1917,7 @@ int soft_offline_page(unsigned long pfn, int flags) { int ret; struct page *page; + bool try_again = true; if (!pfn_valid(pfn)) return -ENXIO; @@ -1932,6 +1933,7 @@ int soft_offline_page(unsigned long pfn, int flags) return 0; } +retry: get_online_mems(); ret = get_any_page(page, pfn, flags); put_online_mems(); @@ -1939,7 +1941,10 @@ int soft_offline_page(unsigned long pfn, int flags) if (ret > 0) ret = soft_offline_in_use_page(page); else if (ret == 0) - ret = soft_offline_free_page(page); + if (soft_offline_free_page(page) && try_again) { + try_again = false; + goto retry; + } return ret; }