From nobody Sun Sep 14 14:22:06 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6B48C05027 for ; Fri, 20 Jan 2023 14:32:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230232AbjATOcN (ORCPT ); Fri, 20 Jan 2023 09:32:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229615AbjATOcM (ORCPT ); Fri, 20 Jan 2023 09:32:12 -0500 X-Greylist: delayed 2131 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Fri, 20 Jan 2023 06:32:11 PST Received: from frasgout11.his.huawei.com (frasgout11.his.huawei.com [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A23393D3; Fri, 20 Jan 2023 06:32:11 -0800 (PST) Received: from mail02.huawei.com (unknown [172.18.147.229]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4Nz16x3JJMz9v7VH; Fri, 20 Jan 2023 21:48:41 +0800 (CST) Received: from huaweicloud.com (unknown [10.206.134.113]) by APP2 (Coremail) with SMTP id GxC2BwDnu2J0ncpj_ryvAA--.23516S2; Fri, 20 Jan 2023 14:56:15 +0100 (CET) From: Hernan Ponce de Leon To: peterz@infradead.org, mingo@redhat.com, will@kernel.org, longman@redhat.com, boqun.feng@gmail.com, akpm@osdl.org, arjan@linux.intel.com, tglx@linutronix.de, joel@joelfernandes.org, paulmck@kernel.org, stern@rowland.harvard.edu, diogo.behrens@huawei.com, jonas.oberhauser@huawei.com Cc: linux-kernel@vger.kernel.org, Hernan Ponce de Leon , stable@vger.kernel.org Subject: [PATCH] Fix data race in mark_rt_mutex_waiters Date: Fri, 20 Jan 2023 14:55:25 +0100 Message-Id: <20230120135525.25561-1-hernan.poncedeleon@huaweicloud.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: GxC2BwDnu2J0ncpj_ryvAA--.23516S2 X-Coremail-Antispam: 1UD129KBjvJXoW7ArW5Gr4kJrWDuw4rtF1rXrb_yoW8JFW3pF W5C3yUG3yqgr1vgrWDW3Z29ayUJ395CrWxW3Z7JryxWr15t3ZFgr9rC3WUWr1FvFWkKFWa vF1Yqr10qrW3Za7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUk2b4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6r106r1rM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxV AFwI0_Gr1j6F4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxAIw28I cxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2 IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI 42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42 IY6xAIw20EY4v20xvaj40_WFyUJVCq3wCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E 87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxUFDGOUUUUU X-CM-SenderInfo: xkhu0tnqos00pfhgvzhhrqqx5xdzvxpfor3voofrz/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Hernan Ponce de Leon Following the defition of data race in tools/memory-model/linux-kernel.cat the dartagnan tool https://github.com/hernanponcedeleon/Dat3M reported a race between mark_rt_mutex_waiters and rt_mutex_cmpxchg_release. Commit 23f78d4a03c5 ("[PATCH] pi-futex: rt mutex core") later removed in commit d0aa7a70bf03 ("futex_requeue_pi optimization") and reverted in commit bd197234b0a6 ("Revert "futex_requeue_pi optimization"") The original commit introduced the data race. Cc: stable@vger.kernel.org # v2.6.18.x Fixes: 23f78d4a03c5 ("[PATCH] pi-futex: rt mutex core") Signed-off-by: Hernan Ponce de Leon --- kernel/locking/rtmutex.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 010cf4e6d0b8..7ed9472edd48 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -235,7 +235,7 @@ static __always_inline void mark_rt_mutex_waiters(struc= t rt_mutex_base *lock) unsigned long owner, *p =3D (unsigned long *) &lock->owner; =20 do { - owner =3D *p; + owner =3D READ_ONCE(*p); } while (cmpxchg_relaxed(p, owner, owner | RT_MUTEX_HAS_WAITERS) !=3D owner); =20 --=20 2.25.1