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 AF5ABC433F5 for ; Sat, 2 Apr 2022 02:24:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237343AbiDBCYD (ORCPT ); Fri, 1 Apr 2022 22:24:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230157AbiDBCYC (ORCPT ); Fri, 1 Apr 2022 22:24:02 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 200CE215936 for ; Fri, 1 Apr 2022 19:22:11 -0700 (PDT) Received: from dggpeml500025.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KVgjP6pVPzDq8S; Sat, 2 Apr 2022 10:19:53 +0800 (CST) Received: from dggpeml500018.china.huawei.com (7.185.36.186) by dggpeml500025.china.huawei.com (7.185.36.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Sat, 2 Apr 2022 10:22:09 +0800 Received: from [10.67.111.186] (10.67.111.186) by dggpeml500018.china.huawei.com (7.185.36.186) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Sat, 2 Apr 2022 10:22:09 +0800 Message-ID: Date: Sat, 2 Apr 2022 10:22:08 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.1.1 Subject: Re: Question about kill a process group From: Zhang Qiao To: lkml CC: References: In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.111.186] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpeml500018.china.huawei.com (7.185.36.186) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping... Any suggestions for this problem？ thank! Qiao 在 2022/3/29 16:07, Zhang Qiao 写道: > hello everyone, > > I got a hradlockup panic when run the ltp syscall testcases. > > 348439.713178] NMI watchdog: Watchdog detected hard LOCKUP on cpu 32 > [348439.713236] irq event stamp: 0 > [348439.713237] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [348439.713238] hardirqs last disabled at (0): [] copy_process+0x7f5/0x2160 > [348439.713239] softirqs last enabled at (0): [] copy_process+0x7f5/0x2160 > [348439.713240] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [348439.713241] CPU: 32 PID: 1151212 Comm: fork12 Kdump: loaded Tainted: G S 5.10.0+ #1 > [348439.713242] Hardware name: Huawei RH2288H V3/BC11HGSA0, BIOS 3.35 10/20/2016 > [348439.713243] RIP: 0010:queued_write_lock_slowpath+0x4d/0x80 > [348439.713245] RSP: 0018:ffffa3a6bed4fe60 EFLAGS: 00000006 > [348439.713246] RAX: 0000000000000500 RBX: ffffffff892060c0 RCX: 00000000000000ff > [348439.713247] RDX: 0000000000000500 RSI: 0000000000000100 RDI: ffffffff892060c0 > [348439.713248] RBP: ffffffff892060c4 R08: 0000000000000001 R09: 0000000000000000 > [348439.713249] R10: ffffa3a6bed4fde8 R11: 0000000000000000 R12: ffff96dfd3b68001 > [348439.713250] R13: ffff96dfd3b68000 R14: ffff96dfd3b68c38 R15: ffff96e2cf1f51c0 > [348439.713251] FS: 0000000000000000(0000) GS:ffff96edbc200000(0000) knlGS:0000000000000000 > [348439.713252] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [348439.713253] CR2: 0000000000416ea0 CR3: 0000002d91812004 CR4: 00000000001706e0 > [348439.713254] Call Trace: > [348439.713255] do_raw_write_lock+0xa9/0xb0 > [348439.713256] _raw_write_lock_irq+0x5a/0x70 > [348439.713256] do_exit+0x429/0xd00 > [348439.713257] do_group_exit+0x39/0xb0 > [348439.713258] __x64_sys_exit_group+0x14/0x20 > [348439.713259] do_syscall_64+0x33/0x40 > [348439.713260] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [348439.713260] RIP: 0033:0x7f59295a7066 > [348439.713261] Code: Unable to access opcode bytes at RIP 0x7f59295a703c. > [348439.713262] RSP: 002b:00007fff0afeac38 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > [348439.713264] RAX: ffffffffffffffda RBX: 00007f5929694530 RCX: 00007f59295a7066 > [348439.713265] RDX: 0000000000000002 RSI: 000000000000003c RDI: 0000000000000002 > [348439.713266] RBP: 0000000000000002 R08: 00000000000000e7 R09: ffffffffffffff80 > [348439.713267] R10: 0000000000000002 R11: 0000000000000246 R12: 00007f5929694530 > [348439.713268] R13: 0000000000000001 R14: 00007f5929697f68 R15: 0000000000000000 > [348439.713269] Kernel panic - not syncing: Hard LOCKUP > [348439.713270] CPU: 32 PID: 1151212 Comm: fork12 Kdump: loaded Tainted: G S 5.10.0+ #1 > [348439.713272] Hardware name: Huawei RH2288H V3/BC11HGSA0, BIOS 3.35 10/20/2016 > [348439.713272] Call Trace: > [348439.713273] > [348439.713274] dump_stack+0x77/0x97 > [348439.713275] panic+0x10c/0x2fb > [348439.713275] nmi_panic+0x35/0x40 > [348439.713276] watchdog_hardlockup_check+0xeb/0x110 > [348439.713277] __perf_event_overflow+0x52/0xf0 > [348439.713278] handle_pmi_common+0x21a/0x320 > [348439.713286] intel_pmu_handle_irq+0xc9/0x1b0 > [348439.713287] perf_event_nmi_handler+0x24/0x40 > [348439.713288] nmi_handle+0xc3/0x2a0 > [348439.713289] default_do_nmi+0x49/0xf0 > [348439.713289] exc_nmi+0x146/0x160 > [348439.713290] end_repeat_nmi+0x16/0x55 > [348439.713291] RIP: 0010:queued_write_lock_slowpath+0x4d/0x80 > [348439.713293] RSP: 0018:ffffa3a6bed4fe60 EFLAGS: 00000006 > [348439.713295] RAX: 0000000000000500 RBX: ffffffff892060c0 RCX: 00000000000000ff > [348439.713296] RDX: 0000000000000500 RSI: 0000000000000100 RDI: ffffffff892060c0 > [348439.713296] RBP: ffffffff892060c4 R08: 0000000000000001 R09: 0000000000000000 > [348439.713297] R10: ffffa3a6bed4fde8 R11: 0000000000000000 R12: ffff96dfd3b68001 > [348439.713298] R13: ffff96dfd3b68000 R14: ffff96dfd3b68c38 R15: ffff96e2cf1f51c0 > [348439.713300] > [348439.713301] do_raw_write_lock+0xa9/0xb0 > [348439.713302] _raw_write_lock_irq+0x5a/0x70 > [348439.713303] do_exit+0x429/0xd00 > [348439.713303] do_group_exit+0x39/0xb0 > [348439.713304] __x64_sys_exit_group+0x14/0x20 > [348439.713305] do_syscall_64+0x33/0x40 > [348439.713306] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [348439.713307] RIP: 0033:0x7f59295a7066 > [348439.713308] Code: Unable to access opcode bytes at RIP 0x7f59295a703c. > > > when analyzing vmcore, i notice lots of fork12 processes are waiting for tasklist read lock or write > lock (see the attachment file all_cpu_stacks.log)，and every fork12 process(belongs to the same > process group) call kill(0, SIGQUIT) in their signal handler()[1], it will traverse all the processes in the > same process group and send signal to them one by one, which is a very time-costly work and hold tasklist > read lock long time. At the same time, other processes will exit after receive signal, they try to get > the tasklist write lock at exit_notify(). > > [1] fork12 testcase: https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/fork/fork12.c > > some processes call kill(0, SIGQUIT), wait for tasklist read lock: > > #5 [ffff972a9b16fd78] native_queued_spin_lock_slowpath at ffffffff9931ed47 > #6 [ffff972a9b16fd78] queued_read_lock_slowpath at ffffffff99320a58 > #7 [ffff972a9b16fd90] do_wait at ffffffff992bc17d > #8 [ffff972a9b16fdd0] kernel_wait4 at ffffffff992bd88d > #9 [ffff972a9b16fe58] __do_sys_wait4 at ffffffff992bd9e5 > #10 [ffff972a9b16ff30] do_syscall_64 at ffffffff9920432d > #11 [ffff972a9b16ff50] entry_SYSCALL_64_after_hwframe at ffffffff99c000ad > > As the same time, some processes are exiting, wait for tasklist write lock: > > #5 [ffff972aa49a7e60] native_queued_spin_lock_slowpath at ffffffff9931ecb0 > #6 [ffff972aa49a7e60] queued_write_lock_slowpath at ffffffff993209e4 > #7 [ffff972aa49a7e78] do_raw_write_lock at ffffffff99320834 > #8 [ffff972aa49a7e88] do_exit at ffffffff992bcd78 > #9 [ffff972aa49a7f00] do_group_exit at ffffffff992bd719 > #10 [ffff972aa49a7f28] __x64_sys_exit_group at ffffffff992bd7a4 > #11 [ffff972aa49a7f30] do_syscall_64 at ffffffff9920432d > #12 [ffff972aa49a7f50] entry_SYSCALL_64_after_hwframe at ffffffff99c000ad > > In this scenario,there are lots of process are waiting for tasklist read lock or the tasklist > write lock, so they will queue. if the wait queue is long enough, it might cause a hardlockup issue when a > process wait for taking the write lock at exit_notify(). > > I tried to solve this problem by avoiding traversing the process group multiple times when kill(0, xxxx) > is called multiple times form the same process group, but it doesn't look like a good solution. > > Is there any good idea for fixing this problem ? > > Thanks! > > Qiao > . >