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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 3EDDFC43387 for ; Wed, 2 Jan 2019 20:59:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC84B21479 for ; Wed, 2 Jan 2019 20:59:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kf7OU3nI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728582AbfABU7n (ORCPT ); Wed, 2 Jan 2019 15:59:43 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:36299 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726941AbfABU7n (ORCPT ); Wed, 2 Jan 2019 15:59:43 -0500 Received: by mail-pg1-f196.google.com with SMTP id n2so15066181pgm.3 for ; Wed, 02 Jan 2019 12:59:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=slOs5HVUDIi/Tpmu6RLaJrzMYZWLNYUNQu8MlH9pJVg=; b=kf7OU3nI0S2hH7AACI8TgRbihF5wMq4j1iybBNcdzj8Ii/cRpXvYcM8afgiYGDtzog JVPpGA6m1iHi4ki+AoGqnd7Fn6JPv21nmOoF3GB8oQ1Q11TUt4y1CXcZcBRYMPkCgbBR G3NDYvWerD+tMhtZX1Z7SKtBxYWNvgReBn+s+Lhd2Znzo40DeAielNeHERmkecPvDOHc MBppGX3/cXrnjkfiMDsS+se2Xdr+Xlrp/o1Z5wsgeeXgcYXeYqo55I03FkeOSbDIueaw bHYgoP7/t+fveVxzFvBuOtzpJufkvMqLUMXNBM7P0RqurmG9Lgwej8+133rVxjVQt12N kDAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=slOs5HVUDIi/Tpmu6RLaJrzMYZWLNYUNQu8MlH9pJVg=; b=fmS/X1w0wiOy02XQCoh3ZCnZAFdVyeNgGhtNriyyLe78GBf6PQWiEGX/59zgIlE3zv BMfJ9olO5zE1xYvmAT05CffdfDXxaY0lmQFMGbjEGBMcY6w6+6EfF9XSeEViSrDdWlU9 jhscUBGQWA5EVaEsOZDwh6swTjz1711Eo3T/gLmswJq+dexRLwI17VmnBEPcKnmCWMxg qZkMhM8iGSPOfNkhYNTRwiXPrF/yepxRCsGe4IC9E9SLiaBW8xcFFRKwhbLhgaF7Ph9r ca1+LhpBZdfNdmSPpZJ5YqhHdhgy/g+YLKecrJPyRJUAiQeymEgLg+yxi54vaC3UfIzh fWzQ== X-Gm-Message-State: AA+aEWYRYzReW2W+/J8usLPGdXmnN3fB488eTHcGmDUrt8xVlpX9ZdLv kbyLxfui0fmxANAaCgdIUyo= X-Google-Smtp-Source: AFSGD/Vvax0pYW9NlZyR7zElkVToNVJU1PJQMm6rUcxN2PSXY1xRgUlx+zn2FTTfvTifgdQRzIFGZA== X-Received: by 2002:a62:4c5:: with SMTP id 188mr46395749pfe.130.1546462781908; Wed, 02 Jan 2019 12:59:41 -0800 (PST) Received: from localhost.localdomain ([2620:0:1008:fd00:78b4:3a07:980a:287b]) by smtp.gmail.com with ESMTPSA id k24sm79185108pfj.13.2019.01.02.12.59.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 02 Jan 2019 12:59:41 -0800 (PST) From: Andrei Vagin To: Alexander Viro , Andrew Morton , Oleg Nesterov Cc: linux-kernel@vger.kernel.org, Andrei Vagin , "Eric W. Biederman" Subject: [PATCH] kernel: release ptraced tasks before zap_pid_ns_processes Date: Wed, 2 Jan 2019 12:59:39 -0800 Message-Id: <20190102205939.26231-1-avagin@gmail.com> X-Mailer: git-send-email 2.17.2 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, exit_ptrace() adds all ptraced tasks in a dead list, than zap_pid_ns_processes() waits all tasks in a current pid ns, and only then tasks from the dead list are released. zap_pid_ns_processes() can stuck on waiting tasks from the dead list. In this case, we will have one unkillable process with one or more dead children. Cc: Oleg Nesterov Cc: "Eric W. Biederman" Cc: Andrew Morton Signed-off-by: Andrei Vagin --- kernel/exit.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 0e21e6d21f35..ccaa6f6549ba 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -664,9 +664,6 @@ static void forget_original_parent(struct task_struct *father, { struct task_struct *p, *t, *reaper; - if (unlikely(!list_empty(&father->ptraced))) - exit_ptrace(father, dead); - /* Can drop and reacquire tasklist_lock */ reaper = find_child_reaper(father); if (list_empty(&father->children)) @@ -705,8 +702,18 @@ static void exit_notify(struct task_struct *tsk, int group_dead) LIST_HEAD(dead); write_lock_irq(&tasklist_lock); - forget_original_parent(tsk, &dead); + if (unlikely(!list_empty(&tsk->ptraced))) + exit_ptrace(tsk, &dead); + write_unlock_irq(&tasklist_lock); + + /* Ptraced tasks have to be released before zap_pid_ns_processes(). */ + list_for_each_entry_safe(p, n, &dead, ptrace_entry) { + list_del_init(&p->ptrace_entry); + release_task(p); + } + write_lock_irq(&tasklist_lock); + forget_original_parent(tsk, &dead); if (group_dead) kill_orphaned_pgrp(tsk->group_leader, NULL); -- 2.17.2