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 705F9C7EE25 for ; Thu, 8 Jun 2023 08:33:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230106AbjFHIde (ORCPT ); Thu, 8 Jun 2023 04:33:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232272AbjFHIdd (ORCPT ); Thu, 8 Jun 2023 04:33:33 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E77C626B2; Thu, 8 Jun 2023 01:33:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=OQw4LAzesIERDw/tpoXXpYhapTxz4emCfmHUIqoyXmc=; b=VUz7MHYyg/m98/jyhEwR0jwBGs k1c3pabfEohSaawm81RVv+cQKRq8jZaORuyZZbyPLAj4uR46aOQ7pwGGNfEEr/+UEnmNS+datSjmb XMgtAFI8ULYEQ9C72GIctLMCcEQX8JZ3Hv9gXNzT3JeJgNUjtU+BbBgXkVz3hqV3vdQqRFCojbWhZ GT44ueppZVlqYp81oh7p6CWzEUok9tPB5NQ82Co8j7kkJOMY8nDNm45gk90ZOObUU/puvVUazjOW4 x8cAWeNgxwqaxoUem5FQtANrzm/mlJPcvPGjsKhby4DIZadHvz2tQHyBBjF5/lbs1FbJmaOfGYzZv kfoIKOxA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1q7B55-00FGiQ-I7; Thu, 08 Jun 2023 08:33:19 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 37F04300274; Thu, 8 Jun 2023 10:33:18 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2124820D72192; Thu, 8 Jun 2023 10:33:18 +0200 (CEST) Date: Thu, 8 Jun 2023 10:33:18 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: "Jain, Ayush" , Linux Next Mailing List , sfr@canb.auug.org.au, rcu@vger.kernel.org, Wyes Karny , linux-kernel@vger.kernel.org, void@manifault.com Subject: Re: Null pointer dereference during rcutorture test on linux-next from next-20230602 Message-ID: <20230608083318.GG998233@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-next@vger.kernel.org On Wed, Jun 07, 2023 at 12:24:12PM -0700, Paul E. McKenney wrote: > On Wed, Jun 07, 2023 at 04:48:19PM +0530, Jain, Ayush wrote: > > Hello All, > > > > Observed null pointer dereference during rcutorture test on linux-next tree > > from next-20230602. > > > > Commit ID: commit bc708bbd8260ee4eb3428b0109f5f3be661fae46 (HEAD, tag: next-20230602) > > > > Here I am attaching log trace > > > > [12133.344278] rcu-torture: rcu_torture_read_exit: Start of test > > [12133.344282] rcu-torture: rcu_torture_read_exit: Start of episode > > [12138.350637] rcu-torture: rcu_torture_read_exit: End of episode > > [12143.419412] smpboot: CPU 1 is now offline > > [12143.427996] BUG: kernel NULL pointer dereference, address: 0000000000000128 > > [12143.435777] #PF: supervisor read access in kernel mode > > [12143.441517] #PF: error_code(0x0000) - not-present page > > [12143.447256] PGD 0 P4D 0 > > [12143.450087] Oops: 0000 [#1] PREEMPT SMP NOPTI > > [12143.454955] CPU: 68 PID: 978653 Comm: rcu_torture_rea Kdump: loaded Not tainted 6.4.0-rc5-next-20230606-1686061107994 #1 > > [12143.467095] Hardware name: AMD Corporation Speedway/Speedway, BIOS RSW1009C 07/27/2018 > > [12143.475934] RIP: 0010:__bitmap_and+0x18/0x70 > > [12143.480713] Code: 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 89 cb 49 89 f9 41 c1 eb 06 74 51 45 89 da 31 c0 45 31 c0 <48> 8b 3c c6 48 23 3c c2 49 89 3c c1 48 83 c0 01 49 09 f8 49 39 c2 > > [12143.501675] RSP: 0018:ffffa3a90db70d90 EFLAGS: 00010046 > > [12143.507510] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000080 > > [12143.515468] RDX: ffff8a1ec17a1d68 RSI: 0000000000000128 RDI: ffff8a1e800429c0 > > [12143.523425] RBP: ffff8a1ec17a1980 R08: 0000000000000000 R09: ffff8a1e800429c0 > > [12143.531385] R10: 0000000000000002 R11: 0000000000000002 R12: ffff8a1e800429c0 > > [12143.539352] R13: 0000000000000000 R14: 0000000000032580 R15: 0000000000000000 > > [12143.547320] FS: 0000000000000000(0000) GS:ffff8a2dbf100000(0000) knlGS:0000000000000000 > > [12143.556354] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [12143.562770] CR2: 0000000000000128 CR3: 0000003089e50000 CR4: 00000000003506e0 > > [12143.570729] Call Trace: > > [12143.573463] > > [12143.575714] ? __die+0x24/0x70 > > [12143.579130] ? page_fault_oops+0x82/0x150 > > [12143.583615] ? exc_page_fault+0x69/0x150 > > [12143.588001] ? asm_exc_page_fault+0x26/0x30 > > [12143.592678] ? __bitmap_and+0x18/0x70 > > [12143.596768] select_idle_cpu+0x84/0x3d0 > > [12143.601059] select_idle_sibling+0x1b7/0x500 > > [12143.605831] select_task_rq_fair+0x1b2/0x2e0 > > [12143.610603] select_task_rq+0x7a/0xc0 > > [12143.614696] try_to_wake_up+0xe8/0x550 > > [12143.618885] ? update_process_times+0x83/0x90 > > [12143.623747] ? __pfx_hrtimer_wakeup+0x10/0x10 > > [12143.628615] hrtimer_wakeup+0x22/0x30 > > [12143.632706] __hrtimer_run_queues+0x112/0x2b0 > > [12143.637574] hrtimer_interrupt+0x100/0x240 > > [12143.642152] __sysvec_apic_timer_interrupt+0x63/0x130 > > [12143.647796] sysvec_apic_timer_interrupt+0x71/0x90 > > [12143.653149] > > [12143.655493] > > [12143.657834] asm_sysvec_apic_timer_interrupt+0x1a/0x20 I'm thikning this is because of ("sched/fair: Multi-LLC select_idle_sibling()") which I've already dropped from tip/sched/core (and should hopefully also dissapear from -next if it hasn't already). Also see: https://lkml.kernel.org/r/20230605175636.GA4253@hirez.programming.kicks-ass.net