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 62533C433EF for ; Fri, 28 Jan 2022 15:43:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349649AbiA1PnD (ORCPT ); Fri, 28 Jan 2022 10:43:03 -0500 Received: from foss.arm.com ([217.140.110.172]:50380 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349641AbiA1PnC (ORCPT ); Fri, 28 Jan 2022 10:43:02 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E493712FC; Fri, 28 Jan 2022 07:43:01 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.13.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4654F3F793; Fri, 28 Jan 2022 07:42:59 -0800 (PST) Date: Fri, 28 Jan 2022 15:42:48 +0000 From: Mark Rutland To: Sven Schnelle Cc: Steven Rostedt , LKML , Ingo Molnar , Andrew Morton , Yinan Liu , Ard Biesheuvel , Kees Cook , Sachin Sant , linuxppc-dev@lists.ozlabs.org, Russell King , linux-arm-kernel@lists.infradead.org, hca@linux.ibm.com, linux-s390@vgr.kernel.org, "Paul E. McKenney" Subject: Re: ftrace hangs waiting for rcu (was: Re: [PATCH] ftrace: Have architectures opt-in for mcount build time sorting) Message-ID: References: <20220127114249.03b1b52b@gandalf.local.home> 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-kernel@vger.kernel.org Hi Sven, On Thu, Jan 27, 2022 at 07:42:35PM +0100, Sven Schnelle wrote: > Mark Rutland writes: > > > * I intermittently see a hang when running the tests. I previously hit that > > when originally trying to bisect this issue (and IIRC that bisected down to > > some RCU changes, but I need to re-run that). When the tests hang I > > magic-srsrq + L tells me: > > > > [ 271.938438] sysrq: Show Blocked State > > [ 271.939245] task:ftracetest state:D stack: 0 pid: 5687 ppid: 5627 flags:0x00000200 > > [ 271.940961] Call trace: > > [ 271.941472] __switch_to+0x104/0x160 > > [ 271.942213] __schedule+0x2b0/0x6e0 > > [ 271.942933] schedule+0x5c/0xf0 > > [ 271.943586] schedule_timeout+0x184/0x1c4 > > [ 271.944410] wait_for_completion+0x8c/0x12c > > [ 271.945274] __wait_rcu_gp+0x184/0x190 > > [ 271.946047] synchronize_rcu_tasks_rude+0x48/0x70 > > [ 271.947007] update_ftrace_function+0xa4/0xec > > [ 271.947897] __unregister_ftrace_function+0xa4/0xf0 > > [ 271.948898] unregister_ftrace_function+0x34/0x70 > > [ 271.949857] wakeup_tracer_reset+0x4c/0x100 > > [ 271.950713] tracing_set_tracer+0xd0/0x2b0 > > [ 271.951552] tracing_set_trace_write+0xe8/0x150 > > [ 271.952477] vfs_write+0xfc/0x284 > > [ 271.953171] ksys_write+0x7c/0x110 > > [ 271.953874] __arm64_sys_write+0x2c/0x40 > > [ 271.954678] invoke_syscall+0x5c/0x130 > > [ 271.955442] el0_svc_common.constprop.0+0x108/0x130 > > [ 271.956435] do_el0_svc+0x74/0x90 > > [ 271.957124] el0_svc+0x2c/0x90 > > [ 271.957757] el0t_64_sync_handler+0xa8/0x12c > > [ 271.958629] el0t_64_sync+0x1a0/0x1a4 On arm64 I bisected this down to: 7a30871b6a27de1a ("rcu-tasks: Introduce ->percpu_enqueue_shift for dynamic queue selection") Which was going wrong because ilog2() rounds down, and so the shift was wrong for any nr_cpus that was not a power-of-two. Paul had already fixed that in rcu-next, and just sent a pull request to Linus: https://lore.kernel.org/lkml/20220128143251.GA2398275@paulmck-ThinkPad-P17-Gen-1/ With that applied, I no longer see these hangs. Does your s390 test machine have a non-power-of-two nr_cpus, and does that fix the issue for you? On arm64 the startup tests didn't seem to trigger the hang, but I was able to trigger the hang fairly reliably with the ftrace selftests, e.g. $ for N in $(seq 1 10); do ./ftracetest test.d/00basic/basic2.tc; done ... which prior to the fix, would hang between runs 2 to 5. Thanks, Mark. > that's interesting. On s390 i'm seeing the same problem in CI, but with > the startup ftrace tests. So that's likely not arm64 spacific. > > On s390, the last messages from ftrace are [ 5.663568] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns > [ 5.667099] futex hash table entries: 65536 (order: 12, 16777216 bytes, vmalloc) > [ 5.739549] Running postponed tracer tests: > [ 5.740662] Testing tracer function: PASSED > [ 6.194635] Testing dynamic ftrace: PASSED > [ 6.471213] Testing dynamic ftrace ops #1: > [ 6.558445] (1 0 1 0 0) > [ 6.558458] (1 1 2 0 0) > [ 6.699135] (2 1 3 0 764347) > [ 6.699252] (2 2 4 0 766466) > [ 6.759857] (3 2 4 0 1159604) > [..] hangs here > > The backtrace looks like this, which is very similar to the one above: > > crash> bt 1 > PID: 1 TASK: 80e68100 CPU: 133 COMMAND: "swapper/0" > #0 [380004df808] __schedule at cda39f0e > #1 [380004df880] schedule at cda3a488 > #2 [380004df8b0] schedule_timeout at cda41ef6 > #3 [380004df978] wait_for_completion at cda3bd0a > #4 [380004df9d8] __wait_rcu_gp at ccdddd92 > #5 [380004dfa30] synchronize_rcu_tasks_generic at ccdde0aa > #6 [380004dfad8] ftrace_shutdown at cce7b050 > #7 [380004dfb18] unregister_ftrace_function at cce7b192 > #8 [380004dfb50] trace_selftest_ops at cda1e0fa > #9 [380004dfba0] run_tracer_selftest at cda1e4f2 > #10 [380004dfc00] trace_selftest_startup_function at ce74355c > #11 [380004dfc58] run_tracer_selftest at cda1e2fc > #12 [380004dfc98] init_trace_selftests at ce742d30 > #13 [380004dfcd0] do_one_initcall at cccdca16 > #14 [380004dfd68] do_initcalls at ce72e776 > #15 [380004dfde0] kernel_init_freeable at ce72ea60 > #16 [380004dfe50] kernel_init at cda333fe > #17 [380004dfe68] __ret_from_fork at cccdf920 > #18 [380004dfe98] ret_from_fork at cda444ca > > I didn't had success reproducing it so far, but it is good to know that > this also happens when running the ftrace testsuite. > > I have several crashdumps, so i could try to pull out some information > if someone tells me what to look for. > > Thanks, > Sven 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 37688C433F5 for ; Fri, 28 Jan 2022 15:43:38 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4JlhZJ3jmxz30Mn for ; Sat, 29 Jan 2022 02:43:36 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=mark.rutland@arm.com; receiver=) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4JlhYm31Blz30Mn for ; Sat, 29 Jan 2022 02:43:05 +1100 (AEDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E493712FC; Fri, 28 Jan 2022 07:43:01 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.13.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4654F3F793; Fri, 28 Jan 2022 07:42:59 -0800 (PST) Date: Fri, 28 Jan 2022 15:42:48 +0000 From: Mark Rutland To: Sven Schnelle Subject: Re: ftrace hangs waiting for rcu (was: Re: [PATCH] ftrace: Have architectures opt-in for mcount build time sorting) Message-ID: References: <20220127114249.03b1b52b@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kees Cook , "Paul E. McKenney" , hca@linux.ibm.com, LKML , Steven Rostedt , Ingo Molnar , linux-s390@vgr.kernel.org, Sachin Sant , Russell King , Andrew Morton , Yinan Liu , linuxppc-dev@lists.ozlabs.org, Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Sven, On Thu, Jan 27, 2022 at 07:42:35PM +0100, Sven Schnelle wrote: > Mark Rutland writes: > > > * I intermittently see a hang when running the tests. I previously hit that > > when originally trying to bisect this issue (and IIRC that bisected down to > > some RCU changes, but I need to re-run that). When the tests hang I > > magic-srsrq + L tells me: > > > > [ 271.938438] sysrq: Show Blocked State > > [ 271.939245] task:ftracetest state:D stack: 0 pid: 5687 ppid: 5627 flags:0x00000200 > > [ 271.940961] Call trace: > > [ 271.941472] __switch_to+0x104/0x160 > > [ 271.942213] __schedule+0x2b0/0x6e0 > > [ 271.942933] schedule+0x5c/0xf0 > > [ 271.943586] schedule_timeout+0x184/0x1c4 > > [ 271.944410] wait_for_completion+0x8c/0x12c > > [ 271.945274] __wait_rcu_gp+0x184/0x190 > > [ 271.946047] synchronize_rcu_tasks_rude+0x48/0x70 > > [ 271.947007] update_ftrace_function+0xa4/0xec > > [ 271.947897] __unregister_ftrace_function+0xa4/0xf0 > > [ 271.948898] unregister_ftrace_function+0x34/0x70 > > [ 271.949857] wakeup_tracer_reset+0x4c/0x100 > > [ 271.950713] tracing_set_tracer+0xd0/0x2b0 > > [ 271.951552] tracing_set_trace_write+0xe8/0x150 > > [ 271.952477] vfs_write+0xfc/0x284 > > [ 271.953171] ksys_write+0x7c/0x110 > > [ 271.953874] __arm64_sys_write+0x2c/0x40 > > [ 271.954678] invoke_syscall+0x5c/0x130 > > [ 271.955442] el0_svc_common.constprop.0+0x108/0x130 > > [ 271.956435] do_el0_svc+0x74/0x90 > > [ 271.957124] el0_svc+0x2c/0x90 > > [ 271.957757] el0t_64_sync_handler+0xa8/0x12c > > [ 271.958629] el0t_64_sync+0x1a0/0x1a4 On arm64 I bisected this down to: 7a30871b6a27de1a ("rcu-tasks: Introduce ->percpu_enqueue_shift for dynamic queue selection") Which was going wrong because ilog2() rounds down, and so the shift was wrong for any nr_cpus that was not a power-of-two. Paul had already fixed that in rcu-next, and just sent a pull request to Linus: https://lore.kernel.org/lkml/20220128143251.GA2398275@paulmck-ThinkPad-P17-Gen-1/ With that applied, I no longer see these hangs. Does your s390 test machine have a non-power-of-two nr_cpus, and does that fix the issue for you? On arm64 the startup tests didn't seem to trigger the hang, but I was able to trigger the hang fairly reliably with the ftrace selftests, e.g. $ for N in $(seq 1 10); do ./ftracetest test.d/00basic/basic2.tc; done ... which prior to the fix, would hang between runs 2 to 5. Thanks, Mark. > that's interesting. On s390 i'm seeing the same problem in CI, but with > the startup ftrace tests. So that's likely not arm64 spacific. > > On s390, the last messages from ftrace are [ 5.663568] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns > [ 5.667099] futex hash table entries: 65536 (order: 12, 16777216 bytes, vmalloc) > [ 5.739549] Running postponed tracer tests: > [ 5.740662] Testing tracer function: PASSED > [ 6.194635] Testing dynamic ftrace: PASSED > [ 6.471213] Testing dynamic ftrace ops #1: > [ 6.558445] (1 0 1 0 0) > [ 6.558458] (1 1 2 0 0) > [ 6.699135] (2 1 3 0 764347) > [ 6.699252] (2 2 4 0 766466) > [ 6.759857] (3 2 4 0 1159604) > [..] hangs here > > The backtrace looks like this, which is very similar to the one above: > > crash> bt 1 > PID: 1 TASK: 80e68100 CPU: 133 COMMAND: "swapper/0" > #0 [380004df808] __schedule at cda39f0e > #1 [380004df880] schedule at cda3a488 > #2 [380004df8b0] schedule_timeout at cda41ef6 > #3 [380004df978] wait_for_completion at cda3bd0a > #4 [380004df9d8] __wait_rcu_gp at ccdddd92 > #5 [380004dfa30] synchronize_rcu_tasks_generic at ccdde0aa > #6 [380004dfad8] ftrace_shutdown at cce7b050 > #7 [380004dfb18] unregister_ftrace_function at cce7b192 > #8 [380004dfb50] trace_selftest_ops at cda1e0fa > #9 [380004dfba0] run_tracer_selftest at cda1e4f2 > #10 [380004dfc00] trace_selftest_startup_function at ce74355c > #11 [380004dfc58] run_tracer_selftest at cda1e2fc > #12 [380004dfc98] init_trace_selftests at ce742d30 > #13 [380004dfcd0] do_one_initcall at cccdca16 > #14 [380004dfd68] do_initcalls at ce72e776 > #15 [380004dfde0] kernel_init_freeable at ce72ea60 > #16 [380004dfe50] kernel_init at cda333fe > #17 [380004dfe68] __ret_from_fork at cccdf920 > #18 [380004dfe98] ret_from_fork at cda444ca > > I didn't had success reproducing it so far, but it is good to know that > this also happens when running the ftrace testsuite. > > I have several crashdumps, so i could try to pull out some information > if someone tells me what to look for. > > Thanks, > Sven 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2E03CC433EF for ; Fri, 28 Jan 2022 15:44:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=JjQNshu6f/fgs9MmhFAOTu7aKIpCfkw43CtIFyO3Fzs=; b=ZYGyOHgyUOjk34 zTm10dq0Mf/BfDQC9LjGbZwwDGV49w7IyF6fM7JQd2oDCB5SQT1pT6WJEXiUZBgrCvN8BBcrLKrQw oR8toJFrWSsNXyUinZJCyfzLXXP2YfZmPr/A5EVe2e1Ioy37+KLCPJotGxbLiD7dPrZMd/x8ZUSwt bbS45qCy2xjR6Pi1iPTcvllXbE3SWFHQlWAZAmW0/ZcNo4pxfcCjxmPCk+KDAPpqOtefPK6y53Ay5 LF/UIXvhvcI+6bQ3D17jCPHbLRdusr3/ZfA3VDb7I/IAeIetsBRcR6pnaAi+t01hHvsDYZDGsh+cq fi9sNPhJ530dUPWJH5AQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nDTP1-002lIW-0r; Fri, 28 Jan 2022 15:43:07 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nDTOx-002lHt-A0 for linux-arm-kernel@lists.infradead.org; Fri, 28 Jan 2022 15:43:05 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E493712FC; Fri, 28 Jan 2022 07:43:01 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.13.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4654F3F793; Fri, 28 Jan 2022 07:42:59 -0800 (PST) Date: Fri, 28 Jan 2022 15:42:48 +0000 From: Mark Rutland To: Sven Schnelle Cc: Steven Rostedt , LKML , Ingo Molnar , Andrew Morton , Yinan Liu , Ard Biesheuvel , Kees Cook , Sachin Sant , linuxppc-dev@lists.ozlabs.org, Russell King , linux-arm-kernel@lists.infradead.org, hca@linux.ibm.com, linux-s390@vgr.kernel.org, "Paul E. McKenney" Subject: Re: ftrace hangs waiting for rcu (was: Re: [PATCH] ftrace: Have architectures opt-in for mcount build time sorting) Message-ID: References: <20220127114249.03b1b52b@gandalf.local.home> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220128_074303_466020_7C71C15E X-CRM114-Status: GOOD ( 22.23 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Sven, On Thu, Jan 27, 2022 at 07:42:35PM +0100, Sven Schnelle wrote: > Mark Rutland writes: > > > * I intermittently see a hang when running the tests. I previously hit that > > when originally trying to bisect this issue (and IIRC that bisected down to > > some RCU changes, but I need to re-run that). When the tests hang I > > magic-srsrq + L tells me: > > > > [ 271.938438] sysrq: Show Blocked State > > [ 271.939245] task:ftracetest state:D stack: 0 pid: 5687 ppid: 5627 flags:0x00000200 > > [ 271.940961] Call trace: > > [ 271.941472] __switch_to+0x104/0x160 > > [ 271.942213] __schedule+0x2b0/0x6e0 > > [ 271.942933] schedule+0x5c/0xf0 > > [ 271.943586] schedule_timeout+0x184/0x1c4 > > [ 271.944410] wait_for_completion+0x8c/0x12c > > [ 271.945274] __wait_rcu_gp+0x184/0x190 > > [ 271.946047] synchronize_rcu_tasks_rude+0x48/0x70 > > [ 271.947007] update_ftrace_function+0xa4/0xec > > [ 271.947897] __unregister_ftrace_function+0xa4/0xf0 > > [ 271.948898] unregister_ftrace_function+0x34/0x70 > > [ 271.949857] wakeup_tracer_reset+0x4c/0x100 > > [ 271.950713] tracing_set_tracer+0xd0/0x2b0 > > [ 271.951552] tracing_set_trace_write+0xe8/0x150 > > [ 271.952477] vfs_write+0xfc/0x284 > > [ 271.953171] ksys_write+0x7c/0x110 > > [ 271.953874] __arm64_sys_write+0x2c/0x40 > > [ 271.954678] invoke_syscall+0x5c/0x130 > > [ 271.955442] el0_svc_common.constprop.0+0x108/0x130 > > [ 271.956435] do_el0_svc+0x74/0x90 > > [ 271.957124] el0_svc+0x2c/0x90 > > [ 271.957757] el0t_64_sync_handler+0xa8/0x12c > > [ 271.958629] el0t_64_sync+0x1a0/0x1a4 On arm64 I bisected this down to: 7a30871b6a27de1a ("rcu-tasks: Introduce ->percpu_enqueue_shift for dynamic queue selection") Which was going wrong because ilog2() rounds down, and so the shift was wrong for any nr_cpus that was not a power-of-two. Paul had already fixed that in rcu-next, and just sent a pull request to Linus: https://lore.kernel.org/lkml/20220128143251.GA2398275@paulmck-ThinkPad-P17-Gen-1/ With that applied, I no longer see these hangs. Does your s390 test machine have a non-power-of-two nr_cpus, and does that fix the issue for you? On arm64 the startup tests didn't seem to trigger the hang, but I was able to trigger the hang fairly reliably with the ftrace selftests, e.g. $ for N in $(seq 1 10); do ./ftracetest test.d/00basic/basic2.tc; done ... which prior to the fix, would hang between runs 2 to 5. Thanks, Mark. > that's interesting. On s390 i'm seeing the same problem in CI, but with > the startup ftrace tests. So that's likely not arm64 spacific. > > On s390, the last messages from ftrace are [ 5.663568] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns > [ 5.667099] futex hash table entries: 65536 (order: 12, 16777216 bytes, vmalloc) > [ 5.739549] Running postponed tracer tests: > [ 5.740662] Testing tracer function: PASSED > [ 6.194635] Testing dynamic ftrace: PASSED > [ 6.471213] Testing dynamic ftrace ops #1: > [ 6.558445] (1 0 1 0 0) > [ 6.558458] (1 1 2 0 0) > [ 6.699135] (2 1 3 0 764347) > [ 6.699252] (2 2 4 0 766466) > [ 6.759857] (3 2 4 0 1159604) > [..] hangs here > > The backtrace looks like this, which is very similar to the one above: > > crash> bt 1 > PID: 1 TASK: 80e68100 CPU: 133 COMMAND: "swapper/0" > #0 [380004df808] __schedule at cda39f0e > #1 [380004df880] schedule at cda3a488 > #2 [380004df8b0] schedule_timeout at cda41ef6 > #3 [380004df978] wait_for_completion at cda3bd0a > #4 [380004df9d8] __wait_rcu_gp at ccdddd92 > #5 [380004dfa30] synchronize_rcu_tasks_generic at ccdde0aa > #6 [380004dfad8] ftrace_shutdown at cce7b050 > #7 [380004dfb18] unregister_ftrace_function at cce7b192 > #8 [380004dfb50] trace_selftest_ops at cda1e0fa > #9 [380004dfba0] run_tracer_selftest at cda1e4f2 > #10 [380004dfc00] trace_selftest_startup_function at ce74355c > #11 [380004dfc58] run_tracer_selftest at cda1e2fc > #12 [380004dfc98] init_trace_selftests at ce742d30 > #13 [380004dfcd0] do_one_initcall at cccdca16 > #14 [380004dfd68] do_initcalls at ce72e776 > #15 [380004dfde0] kernel_init_freeable at ce72ea60 > #16 [380004dfe50] kernel_init at cda333fe > #17 [380004dfe68] __ret_from_fork at cccdf920 > #18 [380004dfe98] ret_from_fork at cda444ca > > I didn't had success reproducing it so far, but it is good to know that > this also happens when running the ftrace testsuite. > > I have several crashdumps, so i could try to pull out some information > if someone tells me what to look for. > > Thanks, > Sven _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel