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 90664C4332F for ; Mon, 5 Dec 2022 15:35:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232078AbiLEPfn (ORCPT ); Mon, 5 Dec 2022 10:35:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231592AbiLEPfm (ORCPT ); Mon, 5 Dec 2022 10:35:42 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70EAE38F; Mon, 5 Dec 2022 07:35:38 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DC946B80D99; Mon, 5 Dec 2022 15:35:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5246AC433C1; Mon, 5 Dec 2022 15:35:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670254535; bh=L5EnuFW8VsNqp9txZnwflmp5QbjPWAAD11OfHOWmnUQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BzcboGooEV3Kpv87rYcBxeWJB+37vqTH1rljGL87BnbZbhttkf8D1bt2cZFWQy1sU GPBGy1mZkz4QVVkbY16LEA5SnmnTHSJDR11HYI2dZskkoPSNRDoRYTZ0wu5kw6cHlw hIBNJ/q8VG9lSmuQqmQgoy1MWVThmTH/JoW3vZUYsMul4JqE9fjTqXMx7EWXLw42JT u+aIAH/YsfywoolRKBbscz3jhCv+BB9JfCnoJ3OomWf2RoXSZGeSoou17+GM3y/j4Y 4rWTq2hJCqJnQCzxl5gGMu86cVE9VNnQYdPYv9qJ4DbwD5np6VO4l0kku+Ic3EkGH1 ABO9MSsFo6BcQ== Date: Mon, 5 Dec 2022 16:35:32 +0100 From: Frederic Weisbecker To: Zheng Yejian Cc: paulmck@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: [PATCH] rcu: Fix kernel stack overflow caused by kprobe on rcu_irq_enter_check_tick() Message-ID: <20221205153532.GA1802155@lothringen> References: <20221119040049.795065-1-zhengyejian1@huawei.com> <20221121195703.GO4001@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Fri, Dec 02, 2022 at 05:54:48PM +0800, Zheng Yejian wrote: > > > On 2022/11/22 03:57, Paul E. McKenney wrote: > > On Sat, Nov 19, 2022 at 12:00:49PM +0800, Zheng Yejian wrote: > > > Register kprobe on __rcu_irq_enter_check_tick() can cause kernel stack > > > overflow [1]. This issue is first found in v5.10 and can be reproduced > > > by enabling CONFIG_NO_HZ_FULL and doing like: > > > # cd /sys/kernel/debug/tracing/ > > > # echo 'p:mp1 __rcu_irq_enter_check_tick' >> kprobe_events > > > # echo 1 > events/kprobes/enable > > > > > > So __rcu_irq_enter_check_tick() should not be kprobed, mark it as noinstr. > > > > Good catch! > > > > I am inclined to queue this, but noticed that one of its callers need > > it to be noinstr but that the others do not. > > > > Need noinstr: > > > > o enter_from_kernel_mode() -> __enter_from_kernel_mode() -> > > rcu_irq_enter_check_tick() -> __rcu_irq_enter_check_tick() > > > > Doesn't need noinstr: > > > > o ct_nmi_enter() -> rcu_irq_enter_check_tick() -> > > __rcu_irq_enter_check_tick(), courtesy of the call to > > instrumentation_begin() in ct_nmi_enter() that precedes the call > > to rcu_irq_enter_check_tick(). > > > > o irqentry_enter() -> rcu_irq_enter_check_tick() -> > > __rcu_irq_enter_check_tick(), courtesy of the call to > > instrumentation_begin() in irqentry_enter() that precedes the > > call to rcu_irq_enter_check_tick(). > > > > Is tagging __rcu_irq_enter_check_tick() with noinstr as > > proposed in this patch the right thing to do, or should there > > be calls to instrumentation_begin() and instrumentation_end() in > > enter_from_kernel_mode()? Or something else entirely? > > I have tried the calls to instrumentation_{begin,end}() in > enter_from_kernel_mode(), see [1]. But this problem can still be > reproduced, maybe more complete calltrace info [2] is needed for > analyzing. > > Did I add the instrumentation_{begin,end}() in wrong place or is there other > caller need noinstr? > > [1] > diff --git a/arch/arm64/kernel/entry-common.c > b/arch/arm64/kernel/entry-common.c > index 27369fa1c032..deed5a0941d3 100644 > --- a/arch/arm64/kernel/entry-common.c > +++ b/arch/arm64/kernel/entry-common.c > @@ -49,7 +49,9 @@ static __always_inline void > __enter_from_kernel_mode(struct pt_regs *regs) > } > > lockdep_hardirqs_off(CALLER_ADDR0); > + instrumentation_begin(); > rcu_irq_enter_check_tick(); > + instrumentation_end(); > trace_hardirqs_off_finish(); > } > > > [2] > [ 48.921197] Call trace: > [ 48.921241] dump_backtrace+0xf8/0x108 > [ 48.921358] show_stack+0x20/0x48 > [ 48.921418] dump_stack_lvl+0x68/0x84 > [ 48.921477] dump_stack+0x1c/0x38 > [ 48.921530] panic+0x214/0x404 > [ 48.921598] add_taint+0x0/0xf0 > [ 48.921657] panic_bad_stack+0x144/0x160 > [ 48.921715] handle_bad_stack+0x38/0x58 > [ 48.921774] __bad_stack+0x78/0x7c > [ 48.921825] __rcu_irq_enter_check_tick+0x0/0x1b8 > [ 48.921886] arm64_enter_el1_dbg.isra.0+0x14/0x20 > [ 48.921949] el1_dbg+0x2c/0x90 > [ 48.922001] el1h_64_sync_handler+0xcc/0xe8 > [ 48.922061] el1h_64_sync+0x64/0x68 > [ 48.922112] __rcu_irq_enter_check_tick+0x0/0x1b8 > [...] > [ 48.938382] __rcu_irq_enter_check_tick+0x0/0x1b8 > [ 48.938441] arm64_enter_el1_dbg.isra.0+0x14/0x20 > [ 48.938500] el1_dbg+0x2c/0x90 > [ 48.938549] el1h_64_sync_handler+0xcc/0xe8 > [ 48.938607] el1h_64_sync+0x64/0x68 > [ 48.938656] __rcu_irq_enter_check_tick+0x0/0x1b8 > [ 48.938715] arm64_enter_el1_dbg.isra.0+0x14/0x20 > [ 48.938778] el1_dbg+0x2c/0x90 > [ 48.938829] el1h_64_sync_handler+0xcc/0xe8 > [ 48.938887] el1h_64_sync+0x64/0x68 > [ 48.938936] __rcu_irq_enter_check_tick+0x0/0x1b8 > [ 48.938995] arm64_enter_el1_dbg.isra.0+0x14/0x20 > [ 48.939054] el1_dbg+0x2c/0x90 > [ 48.939105] el1h_64_sync_handler+0xcc/0xe8 > [ 48.939164] el1h_64_sync+0x64/0x68 > [ 48.939215] __rcu_irq_enter_check_tick+0x0/0x1b8 Well, that looks strange. If that is called under instrumentation_begin()... +Cc: Peter in case he has an idea. Thanks. > [ 48.939274] el1_interrupt+0x28/0x60 > [ 48.939327] el1h_64_irq_handler+0x18/0x28 > [ 48.939385] el1h_64_irq+0x64/0x68 > [ 48.939434] __asan_load8+0x54/0xa8 > [ 48.939500] __ftrace_set_clr_event_nolock+0x6c/0x198 > [ 48.939563] __ftrace_set_clr_event+0x58/0x80 > [ 48.939618] system_enable_write+0x144/0x178 > [ 48.939673] vfs_write+0x174/0x738 > [ 48.939734] ksys_write+0xd0/0x188 > [ 48.939791] __arm64_sys_write+0x4c/0x60 > [ 48.939851] invoke_syscall+0x64/0x180 > [ 48.939921] el0_svc_common.constprop.0+0x84/0x160 > [ 48.939996] do_el0_svc+0x48/0xf8 > [ 48.940062] el0_svc+0x34/0xd0 > [ 48.940114] el0t_64_sync_handler+0xb8/0xc0 > [ 48.940173] el0t_64_sync+0x18c/0x190 > [ 48.940872] SMP: stopping secondary CPUs > [ 48.942844] Kernel Offset: 0x2d9499c00000 from 0xffff800008000000 > [ 48.942938] PHYS_OFFSET: 0xffffaa9840000000 > [ 48.942999] CPU features: 0x00000,00d00080,0000421b > [ 48.943387] Memory Limit: none > > > > > > Thoughts? > > Sorry, I have no more idea :-( > > > > > Thanx, Paul > > > > > [1] > > > Insufficient stack space to handle exception! > > > Insufficient stack space to handle exception! > > > [...] > > > Kernel panic - not syncing: kernel stack overflow > > > CPU: 3 PID: 34 Comm: migration/3 Not tainted > > > 6.1.0-rc5-00884-g84368d882b96 #2 > > > Hardware name: linux,dummy-virt (DT) > > > Stopper: multi_cpu_stop+0x0/0x228 <- __stop_cpus.constprop.0+0xa4/0x100 > > > Call trace: > > > dump_backtrace+0xf8/0x108 > > > show_stack+0x20/0x48 > > > dump_stack_lvl+0x68/0x84 > > > dump_stack+0x1c/0x38 > > > panic+0x214/0x404 > > > add_taint+0x0/0xf0 > > > panic_bad_stack+0x144/0x160 > > > handle_bad_stack+0x38/0x58 > > > __bad_stack+0x78/0x7c > > > el1h_64_sync_handler+0x4/0xe8 > > > __rcu_irq_enter_check_tick+0x0/0x1b8 > > > arm64_enter_el1_dbg.isra.0+0x14/0x20 > > > el1_dbg+0x2c/0x90 > > > el1h_64_sync_handler+0xcc/0xe8 > > > el1h_64_sync+0x64/0x68 > > > __rcu_irq_enter_check_tick+0x0/0x1b8 > > > arm64_enter_el1_dbg.isra.0+0x14/0x20 > > > el1_dbg+0x2c/0x90 > > > el1h_64_sync_handler+0xcc/0xe8 > > > el1h_64_sync+0x64/0x68 > > > __rcu_irq_enter_check_tick+0x0/0x1b8 > > > arm64_enter_el1_dbg.isra.0+0x14/0x20 > > > el1_dbg+0x2c/0x90 > > > el1h_64_sync_handler+0xcc/0xe8 > > > el1h_64_sync+0x64/0x68 > > > __rcu_irq_enter_check_tick+0x0/0x1b8 > > > arm64_enter_el1_dbg.isra.0+0x14/0x20 > > > el1_dbg+0x2c/0x90 > > > el1h_64_sync_handler+0xcc/0xe8 > > > el1h_64_sync+0x64/0x68 > > > __rcu_irq_enter_check_tick+0x0/0x1b8 > > > arm64_enter_el1_dbg.isra.0+0x14/0x20 > > > el1_dbg+0x2c/0x90 > > > el1h_64_sync_handler+0xcc/0xe8 > > > el1h_64_sync+0x64/0x68 > > > __rcu_irq_enter_check_tick+0x0/0x1b8 > > > [...] > > > > > > Cc: stable@vger.kernel.org > > > Fixes: aaf2bc50df1f ("rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter()") > > > Signed-off-by: Zheng Yejian > > > --- > > > kernel/rcu/tree.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > > index 93416afebd59..68230f02cfb7 100644 > > > --- a/kernel/rcu/tree.c > > > +++ b/kernel/rcu/tree.c > > > @@ -631,7 +631,7 @@ void rcu_irq_exit_check_preempt(void) > > > * controlled environments, this function allows RCU to get what it > > > * needs without creating otherwise useless interruptions. > > > */ > > > -void __rcu_irq_enter_check_tick(void) > > > +noinstr void __rcu_irq_enter_check_tick(void) > > > { > > > struct rcu_data *rdp = this_cpu_ptr(&rcu_data); > > > -- > > > 2.25.1 > > > > -- > Best regards, > Zheng Yejian