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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0AFC2C433EF for ; Wed, 11 May 2022 17:37:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345677AbiEKRhr (ORCPT ); Wed, 11 May 2022 13:37:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234039AbiEKRhl (ORCPT ); Wed, 11 May 2022 13:37:41 -0400 Received: from out02.mta.xmission.com (out02.mta.xmission.com [166.70.13.232]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99FAD692AC; Wed, 11 May 2022 10:37:40 -0700 (PDT) Received: from in01.mta.xmission.com ([166.70.13.51]:58578) by out02.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1noqHJ-006mps-BT; Wed, 11 May 2022 11:37:37 -0600 Received: from ip68-227-174-4.om.om.cox.net ([68.227.174.4]:37816 helo=email.froward.int.ebiederm.org.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1noqHH-001c0M-Bx; Wed, 11 May 2022 11:37:36 -0600 From: "Eric W. Biederman" To: Cc: Tejun Heo , Peter Zijlstra , Vincent Guittot , Al Viro , Jens Axboe , Thomas Gleixner , Linus Torvalds , References: <87a6czifo7.fsf@email.froward.int.ebiederm.org> <87ilrn1drx.ffs@tglx> <877d7zk1cf.ffs@tglx> <87y20fid4d.ffs@tglx> <87bkx5q3pk.fsf_-_@email.froward.int.ebiederm.org> <87mtfu4up3.fsf@email.froward.int.ebiederm.org> Date: Wed, 11 May 2022 12:37:10 -0500 In-Reply-To: <87mtfu4up3.fsf@email.froward.int.ebiederm.org> (Eric W. Biederman's message of "Fri, 06 May 2022 09:11:36 -0500") Message-ID: <87r150ug1l.fsf_-_@email.froward.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1noqHH-001c0M-Bx;;;mid=<87r150ug1l.fsf_-_@email.froward.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=68.227.174.4;;;frm=ebiederm@xmission.com;;;spf=softfail X-XM-AID: U2FsdGVkX19mmGlUvgKMqbZ/amgfpc+1CZO+CoJffcI= X-SA-Exim-Connect-IP: 68.227.174.4 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH 8/7] sched: Update task_tick_numa to ignore tasks without an mm X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Qian Cai wrote: > Reverting the last 3 commits of the series fixed a boot crash. > > 1b2552cbdbe0 fork: Stop allowing kthreads to call execve > 753550eb0ce1 fork: Explicitly set PF_KTHREAD > 68d85f0a33b0 init: Deal with the init process being a user mode process > > BUG: KASAN: null-ptr-deref in task_nr_scan_windows.isra.0 > arch_atomic_long_read at ./include/linux/atomic/atomic-long.h:29 > (inlined by) atomic_long_read at ./include/linux/atomic/atomic-instrumented.h:1266 > (inlined by) get_mm_counter at ./include/linux/mm.h:1996 > (inlined by) get_mm_rss at ./include/linux/mm.h:2049 > (inlined by) task_nr_scan_windows at kernel/sched/fair.c:1123 > Read of size 8 at addr 00000000000003d0 by task swapper/0/1 With the change to init and the user mode helper processes to not have PF_KTHREAD set before they call kernel_execve the PF_KTHREAD test in task_tick_numa became insufficient to detect all tasks that have "->mm == NULL". Correct that by testing for "->mm == NULL" directly. Reported-by: Qian Cai Tested-by: Qian Cai Fixes: 1b2552cbdbe0 ("fork: Stop allowing kthreads to call execve") Signed-off-by: "Eric W. Biederman" --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d4bd299d67ab..db6f0df9d43e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2915,7 +2915,7 @@ static void task_tick_numa(struct rq *rq, struct task_struct *curr) /* * We don't care about NUMA placement if we don't have memory. */ - if ((curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work) + if (!curr->mm || (curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work) return; /* -- 2.35.3