From nobody Tue Sep 16 14:11:51 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 EC345C5479D for ; Mon, 2 Jan 2023 15:13:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236268AbjABPNR (ORCPT ); Mon, 2 Jan 2023 10:13:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53622 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236231AbjABPMt (ORCPT ); Mon, 2 Jan 2023 10:12:49 -0500 Received: from smtpout.efficios.com (unknown [IPv6:2607:5300:203:b2ee::31e5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87C338FE6; Mon, 2 Jan 2023 07:12:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1672672364; bh=NXjw6+rKKlfiUhcOC13HUdlVvOIiNsxG9TWj+5AVcIw=; h=From:To:Cc:Subject:Date:From; b=r5UT4MIPL/pFPmCMszOD5+rkZ6FAF+gPIqMWw+xNObFLDXaU5dEIECX4G5qNxSVou NRrFMJn9sf9dZRb4/DWw/tKk75H3GzNRczXAfQFZr1EWlVPXUKvXxjPqJB4BR4jgU5 1MfD5fEv8tS1THB/ulXN+i+K+t3qmETRwq7N5grONjL2C8qIsnOSxEr3NIm673R383 AOv1kKzusKsqYGOfLqwfMGm04BF4bQTWPPTy0VNkRuztC0WxSJH9eivZsCkPDeHAF9 fdyaKiYvdlV84k3Sziil0EEjY46KIxZQAaOwuoE4mRMwJdizSESccDpu9hSW9me0wT h0mN/nL29MJVg== Received: from localhost.localdomain (192-222-180-24.qc.cable.ebox.net [192.222.180.24]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4NlzrC6lcrzd3y; Mon, 2 Jan 2023 10:12:43 -0500 (EST) From: Mathieu Desnoyers To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , "Paul E . McKenney" , Boqun Feng , "H . Peter Anvin" , Paul Turner , linux-api@vger.kernel.org, Christian Brauner , Florian Weimer , David.Laight@ACULAB.COM, carlos@redhat.com, Peter Oskolkov , Alexander Mikhalitsyn , Chris Kennelly , Mathieu Desnoyers , kernel test robot , Borislav Petkov Subject: [RFC PATCH for tip] sched: Fix concurrency ID handling of usermodehelper kthreads Date: Mon, 2 Jan 2023 10:12:16 -0500 Message-Id: <20230102151216.328117-1-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" sched_mm_cid_after_execve does not expect NULL t->mm, but it may happen if a usermodehelper kthread fails when attempting to execute a binary. sched_mm_cid_fork can be issued from a usermodehelper kthread, which has t->flags PF_KTHREAD set. Fixes: af7f588d8f73 ("sched: Introduce per-memory-map concurrency ID") Reported-by: kernel test robot Link: https://lore.kernel.org/oe-lkp/202212301353.5c959d72-yujie.liu@intel.= com Reported-by: Borislav Petkov Signed-off-by: Mathieu Desnoyers --- kernel/sched/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 048ec2417990..f99ee69867e3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -11343,8 +11343,8 @@ void sched_mm_cid_after_execve(struct task_struct *= t) struct mm_struct *mm =3D t->mm; unsigned long flags; =20 - WARN_ON_ONCE((t->flags & PF_KTHREAD) || !t->mm); - + if (!mm) + return; local_irq_save(flags); t->mm_cid =3D mm_cid_get(mm); t->mm_cid_active =3D 1; @@ -11354,7 +11354,7 @@ void sched_mm_cid_after_execve(struct task_struct *= t) =20 void sched_mm_cid_fork(struct task_struct *t) { - WARN_ON_ONCE((t->flags & PF_KTHREAD) || !t->mm || t->mm_cid !=3D -1); + WARN_ON_ONCE(!t->mm || t->mm_cid !=3D -1); t->mm_cid_active =3D 1; } #endif --=20 2.25.1