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=-9.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 BDBDBC4363C for ; Thu, 8 Oct 2020 13:00:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DA1D207DE for ; Thu, 8 Oct 2020 13:00:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730197AbgJHNAe (ORCPT ); Thu, 8 Oct 2020 09:00:34 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:42187 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730173AbgJHNAd (ORCPT ); Thu, 8 Oct 2020 09:00:33 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=wenyang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0UBIzwIH_1602162022; Received: from localhost(mailfrom:wenyang@linux.alibaba.com fp:SMTPD_---0UBIzwIH_1602162022) by smtp.aliyun-inc.com(127.0.0.1); Thu, 08 Oct 2020 21:00:28 +0800 From: Wen Yang To: Greg Kroah-Hartman , Sasha Levin Cc: Wen Yang , "Eric W . Biederman" , stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Stable backport request for fixing the issue of not being able to create a new pid_ns Date: Thu, 8 Oct 2020 21:00:21 +0800 Message-Id: <20201008130021.79829-1-wenyang@linux.alibaba.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After the process exits, the following three dentries still refer to the pid: /proc/ /proc//ns /proc//ns/pid https://bugzilla.kernel.org/show_bug.cgi?id=208613 According to the commit f333c700c610 ("pidns: Add a limit on the number of pid namespaces"), if the pid cannot be released, it may result in the inability to create a new pid_ns. Please backport the following patches to the kernel stable trees (from 4.9.y to 5.6.y): 7bc3e6e55acf ("proc: Use a list of inodes to flush from proc") 26dbc60f385f ("proc: Generalize proc_sys_prune_dcache into proc_prune_siblings_dcache") f90f3cafe8d5 ("proc: Use d_invalidate in proc_prune_siblings_dcache") Signed-off-by: Wen Yang Cc: Eric W. Biederman Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org