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 DFFD6C433EF for ; Sat, 12 Feb 2022 22:30:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232106AbiBLWa5 (ORCPT ); Sat, 12 Feb 2022 17:30:57 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:41856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229532AbiBLWa4 (ORCPT ); Sat, 12 Feb 2022 17:30:56 -0500 X-Greylist: delayed 564 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sat, 12 Feb 2022 14:30:52 PST Received: from mail-41103.protonmail.ch (mail-41103.protonmail.ch [185.70.41.103]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A05460A84 for ; Sat, 12 Feb 2022 14:30:52 -0800 (PST) Received: from mail-0301.mail-europe.com (mail-0301.mail-europe.com [188.165.51.139]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by mail-41103.protonmail.ch (Postfix) with ESMTPS id 4Jx4hR2FHyz4xGGd for ; Sat, 12 Feb 2022 22:21:27 +0000 (UTC) Authentication-Results: mail-41103.protonmail.ch; dkim=pass (2048-bit key) header.d=pm.me header.i=@pm.me header.b="BOwEQaoN" Date: Sat, 12 Feb 2022 22:21:11 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail2; t=1644704481; bh=ryu2oTX8un4bZO5aF2kiNhHdcBaW57NJk9xC8bxjxWI=; h=Date:To:From:Cc:Reply-To:Subject:Message-ID:From:To:Cc:Date: Subject:Reply-To:Feedback-ID:Message-ID; b=BOwEQaoNJ9gUhvKzLyzWSmrumL727bl9a//yWCI7WeudDkmHE98BDsGHyvqyYvdvX ZnRYQ0D1kl6fdsDNTCI46OQK0tLBRWIpJb/+5DiyHa1HARSL6nw0jZRHHvy+GFINtf +ncjWuhd857xRL2n6bimZAvUtrjrVkcVkESealWWZKnKsPUgJ/4dnhLRxS0GJPs5RU mYoaPBRLHB5kkqc4DAGm2QJf/uDuoO+9FpiWiuJk+QItLZGYCxu5JYBc8d8Z8Epoog oX10by4GjjCDr7hCHoX/DQBD3BrMjojYUEuM8XbThGR6Uh6IUQ9KOQQ+whoKhwe0Nf XXt+ZihtAwEuw== To: Thomas Bogendoerfer From: Alexander Lobakin Cc: Valentin Schneider , Ingo Molnar , Peter Zijlstra , Alexander Lobakin , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Reply-To: Alexander Lobakin Subject: [PATCH mips-fixes] MIPS: smp: fill in sibling and core maps earlier Message-ID: <20220212221347.442070-1-alobakin@pm.me> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After enabling CONFIG_SCHED_CORE (landed during 5.14 cycle), 2-core 2-thread-per-core interAptiv (CPS-driven) started emitting the following: [ 0.025698] CPU1 revision is: 0001a120 (MIPS interAptiv (multi)) [ 0.048183] ------------[ cut here ]------------ [ 0.048187] WARNING: CPU: 1 PID: 0 at kernel/sched/core.c:6025 sched_cor= e_cpu_starting+0x198/0x240 [ 0.048220] Modules linked in: [ 0.048233] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.17.0-rc3+ #35 b7= b319f24073fd9a3c2aa7ad15fb7993eec0b26f [ 0.048247] Stack : 817f0000 00000004 327804c8 810eb050 00000000 0000000= 4 00000000 c314fdd1 [ 0.048278] 830cbd64 819c0000 81800000 817f0000 83070bf4 0000000= 1 830cbd08 00000000 [ 0.048307] 00000000 00000000 815fcbc4 00000000 00000000 0000000= 0 00000000 00000000 [ 0.048334] 00000000 00000000 00000000 00000000 817f0000 0000000= 0 00000000 817f6f34 [ 0.048361] 817f0000 818a3c00 817f0000 00000004 00000000 0000000= 0 4dc33260 0018c933 [ 0.048389] ... [ 0.048396] Call Trace: [ 0.048399] [<8105a7bc>] show_stack+0x3c/0x140 [ 0.048424] [<8131c2a0>] dump_stack_lvl+0x60/0x80 [ 0.048440] [<8108b5c0>] __warn+0xc0/0xf4 [ 0.048454] [<8108b658>] warn_slowpath_fmt+0x64/0x10c [ 0.048467] [<810bd418>] sched_core_cpu_starting+0x198/0x240 [ 0.048483] [<810c6514>] sched_cpu_starting+0x14/0x80 [ 0.048497] [<8108c0f8>] cpuhp_invoke_callback_range+0x78/0x140 [ 0.048510] [<8108d914>] notify_cpu_starting+0x94/0x140 [ 0.048523] [<8106593c>] start_secondary+0xbc/0x280 [ 0.048539] [ 0.048543] ---[ end trace 0000000000000000 ]--- [ 0.048636] Synchronize counters for CPU 1: done. ...for each but CPU 0/boot. Basic debug printks right before the mentioned line say: [ 0.048170] CPU: 1, smt_mask: So smt_mask, which is sibling mask obviously, is empty when entering the function. This is critical, as sched_core_cpu_starting() calculates core-scheduling parameters only once per CPU start, and it's crucial to have all the parameters filled in at that moment (at least it uses cpu_smt_mask() which in fact is `&cpu_sibling_map[cpu]` on MIPS). A bit of debugging led me to that set_cpu_sibling_map() performing the actual map calculation, was being invocated after notify_cpu_start(), and exactly the latter function starts CPU HP callback round (sched_core_cpu_starting() is basically a CPU HP callback). While the flow is same on ARM64 (maps after the notifier, although before calling set_cpu_online()), x86 started calculating sibling maps earlier than starting the CPU HP callbacks in Linux 4.14 (see [0] for the reference). Neither me nor my brief tests couldn't find any potential caveats in calculating the maps right after performing delay calibration, but the WARN splat is now gone. The very same debug prints now yield exactly what I expected from them: [ 0.048433] CPU: 1, smt_mask: 0-1 [0] https://git.kernel.org/pub/scm/linux/kernel/git/mips/linux.git/commit/?= id=3D76ce7cfe35ef Signed-off-by: Alexander Lobakin --- arch/mips/kernel/smp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c index d542fb7af3ba..1986d1309410 100644 --- a/arch/mips/kernel/smp.c +++ b/arch/mips/kernel/smp.c @@ -351,6 +351,9 @@ asmlinkage void start_secondary(void) =09cpu =3D smp_processor_id(); =09cpu_data[cpu].udelay_val =3D loops_per_jiffy; +=09set_cpu_sibling_map(cpu); +=09set_cpu_core_map(cpu); + =09cpumask_set_cpu(cpu, &cpu_coherent_mask); =09notify_cpu_starting(cpu); @@ -362,9 +365,6 @@ asmlinkage void start_secondary(void) =09/* The CPU is running and counters synchronised, now mark it online */ =09set_cpu_online(cpu, true); -=09set_cpu_sibling_map(cpu); -=09set_cpu_core_map(cpu); - =09calculate_cpu_foreign_map(); =09/* -- 2.35.1