Received: by 2002:a05:6a10:f347:0:0:0:0 with SMTP id d7csp772637pxu; Thu, 3 Dec 2020 12:13:26 -0800 (PST) X-Google-Smtp-Source: ABdhPJzk1Zlm1rve4nwTjQgmXLK1jK/DKeCeZdfLkhWZBoWVutlwSPrQFRlYQ7ydlsuZ7vuW/rd+ X-Received: by 2002:aa7:db59:: with SMTP id n25mr3321952edt.203.1607026405944; Thu, 03 Dec 2020 12:13:25 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1607026405; cv=none; d=google.com; s=arc-20160816; b=K+GD3VN649FdNdHjIsUDkCS6DzpnOqQypcuvlo2LjcpYlzJhXQGuOQDl7i53CnN0bV S/BUJkZizPDKrvbR6N3HhyM1knCJOr20AuN2ZDo1DZfEgg0R1PZfQpup/jviBbmZ0M7P TPyy4U41PqAtroXRxfSrCcL6vuufRPEE48IxSEhgNFM83CbEUhxHdGhm0cmAgC5mskCd stAjVk87suZQCAAzV2jLpDnrl9tkpGlsWd51G4EEmpz460Wb6kDSEyqGuv7Mm466gqoQ XtwUmNk9ykCv3Ao27LwW2890/90FBSSw4Yn/ytCk495PaR7krW6YWuPI9qHBKod+nRQP nO6A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:subject:mime-version:user-agent:message-id:date :cc:to:from; bh=X+RGpHOUdfCbatLsC7VtvIi5BhBbi6ZlIZLGFQeip4Q=; b=KPVz3sH04lRwbNEQJQvkpMIqitevgjNaL6N8CNAF4Iaxc184SRwhUeSLo4OI1Vv+RC I0R7YTWyJqHzeWM+TGLATheHAEti1j+qaLZw0pP8VWsrTBW4BsyfB7XF3yYSPYyiIugz Zcb4VUV/kVXwRCmND5LM/PwqvyDPWzdt1ycxFg8Xu4ZTbWyweeKSH75P/hOUOOtS8k9N 5qm+6IF/MGhgixplwXI7V6IUmCWjpwizZKlcQwMlbR38hJpsG9Jlho+NxtqwURRkjVfY 4zB4oJIJr+99AcQTwcp5J6h3ruSDAXGxG6vRPu8VOMFcbb2ycurYLvfqqVYNfOFOhurw 79KQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=xmission.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id x17si1803615edq.475.2020.12.03.12.13.03; Thu, 03 Dec 2020 12:13:25 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=xmission.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731119AbgLCULC (ORCPT + 99 others); Thu, 3 Dec 2020 15:11:02 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:56650 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726681AbgLCULB (ORCPT ); Thu, 3 Dec 2020 15:11:01 -0500 Received: from in02.mta.xmission.com ([166.70.13.52]) by out03.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1kkuvd-00BMPH-Py; Thu, 03 Dec 2020 13:10:13 -0700 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1kkuvc-00B32W-N8; Thu, 03 Dec 2020 13:10:13 -0700 From: ebiederm@xmission.com (Eric W. Biederman) To: Cc: Linus Torvalds , Peter Zijlstra , Ingo Molnar , Will Deacon , Jann Horn , Vasiliy Kulikov , Al Viro , Bernd Edlinger , Oleg Nesterov , Christopher Yeoh , Cyrill Gorcunov , Sargun Dhillon , Christian Brauner , Arnd Bergmann , Arnaldo Carvalho de Melo Date: Thu, 03 Dec 2020 14:09:39 -0600 Message-ID: <87tut2bqik.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1kkuvc-00B32W-N8;;;mid=<87tut2bqik.fsf@x220.int.ebiederm.org>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+KAKkx+upN+DyhS/e8mfHxnCYAh8W63fM= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on sa02.xmission.com X-Spam-Level: *** X-Spam-Status: No, score=3.5 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,TR_XM_SB_Phish,T_TooManySym_01,XMNoVowels,XMSubLong, XMSubPhish11 autolearn=disabled version=3.4.2 X-Spam-Virus: No X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.4988] * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.7 XMSubLong Long Subject * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa02 1397; Body=1 Fuz1=1 Fuz2=1] * 1.5 XMSubPhish11 Phishy Language Subject * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 TR_XM_SB_Phish Phishing flag in subject of message X-Spam-DCC: XMission; sa02 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ***; X-Spam-Relay-Country: X-Spam-Timing: total 438 ms - load_scoreonly_sql: 0.03 (0.0%), signal_user_changed: 3.5 (0.8%), b_tie_ro: 2.4 (0.5%), parse: 0.56 (0.1%), extract_message_metadata: 2.1 (0.5%), get_uri_detail_list: 0.70 (0.2%), tests_pri_-1000: 3.2 (0.7%), tests_pri_-950: 1.02 (0.2%), tests_pri_-900: 0.82 (0.2%), tests_pri_-90: 201 (45.9%), check_bayes: 200 (45.7%), b_tokenize: 4.7 (1.1%), b_tok_get_all: 6 (1.3%), b_comp_prob: 1.37 (0.3%), b_tok_touch_all: 185 (42.3%), b_finish: 0.70 (0.2%), tests_pri_0: 212 (48.5%), check_dkim_signature: 0.34 (0.1%), check_dkim_adsp: 2.1 (0.5%), poll_dns_idle: 0.70 (0.2%), tests_pri_10: 1.77 (0.4%), tests_pri_500: 6 (1.4%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH 0/3] exec: Transform exec_update_mutex into a rw_semaphore X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Recently syzbot reported[0] that there is a deadlock amongst the users of exec_update_mutex. The simplest and most robust solution appears to be making exec_update_mutex a read/write lock and having everything execept for exec take the lock for read. This set of changes upgrades rwsem so it has the functionality needed and uses a rw_semaphore to replace the current mutex. Eric W. Biederman (3): rwsem: Implement down_read_killable_nested rwsem: Implement down_read_interruptible exec: Transform exec_update_mutex into a rw_semaphore fs/exec.c | 12 ++++++------ fs/proc/base.c | 10 +++++----- include/linux/rwsem.h | 3 +++ include/linux/sched/signal.h | 11 ++++++----- init/init_task.c | 2 +- kernel/events/core.c | 12 ++++++------ kernel/fork.c | 6 +++--- kernel/kcmp.c | 30 +++++++++++++++--------------- kernel/locking/rwsem.c | 40 ++++++++++++++++++++++++++++++++++++++++ kernel/pid.c | 4 ++-- 10 files changed, 87 insertions(+), 43 deletions(-) [0] https://lkml.kernel.org/r/00000000000063640c05ade8e3de@google.com Eric