linux-kernel - Re: [PATCH] rcu/torture: Improve badness extraction from console logs

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Message-ID: <b292cca4-d451-4371-ae2e-9417e0079e84@paulmck-laptop>
Date:   Fri, 1 Sep 2023 07:49:24 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Shuah Khan <shuah@...nel.org>, rcu@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH] rcu/torture: Improve badness extraction from console logs

On Thu, Aug 31, 2023 at 01:22:56AM +0000, Joel Fernandes (Google) wrote:
> Currently console.log.diags contains an output like follows:
> [ 2457.293734] WARNING: CPU: 2 PID: 13 at kernel/rcu/tasks.h:1061 rcu_tasks_trace_pregp_step+0x4a/0x50
> [ 2457.542385] Call Trace:
> 
> This is not very useful and the Call trace is desired. Improve the
> script by Extracting more lines after each grep match.
> 
> With this the above becomes:
> 
> Issue 1:
> [ 2457.293734] WARNING: CPU: 2 PID: 13 at kernel/rcu/tasks.h:1061 rcu_tasks_trace_pregp_step+0x4a/0x50
> [ 2457.326661] Modules linked in:
> [ 2457.334818] CPU: 2 PID: 13 Comm: rcu_tasks_trace Not tainted 5.15.128+ #381
> [ 2457.349782] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> [ 2457.373309] RIP: 0010:rcu_tasks_trace_pregp_step+0x4a/0x50
> [ 2457.386691] Code: 48 63 c7 48 8b 0
> [ 2457.421803] RSP: 0018:ffffa80fc0073e40 EFLAGS: 00010202
> [ 2457.431940] RAX: ffff8db91f580000 RBX: 000000000001b900 RCX: 0000000000000003
> [ 2457.443206] RDX: 0000000000000008 RSI: ffffffffac6bebd8 RDI: 0000000000000003
> [ 2457.454428] RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000001
> [ 2457.465668] R10: 0000000000000000 R11: 00000000ffffffff R12: ffff8db902d87f40
> [ 2457.476971] R13: ffffffffac556620 R14: ffffffffac556630 R15: ffff8db9011a3200
> [ 2457.488251] FS:  0000000000000000(0000) GS:ffff8db91f500000(0000) knlGS:0000000000000000
> [ 2457.500834] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 2457.509602] CR2: 0000000000000000 CR3: 0000000002cbc000 CR4: 00000000000006e0
> [ 2457.520378] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 2457.531440] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 2457.542385] Call Trace:
> [ 2457.546756]  <TASK>
> [ 2457.550349]  ? __warn+0x7b/0x100
> [ 2457.567214]  ? rcu_tasks_trace_pregp_step+0x4a/0x50
> -------------------------------------
> Issue 2:
> [ 2457.542385] Call Trace:
> [ 2457.546756]  <TASK>
> [ 2457.550349]  ? __warn+0x7b/0x100
> [ 2457.567214]  ? rcu_tasks_trace_pregp_step+0x4a/0x50
> [ 2457.574948]  ? report_bug+0x99/0xc0
> [ 2457.593824]  ? handle_bug+0x3c/0x70
> [ 2457.599534]  ? exc_invalid_op+0x13/0x60
> [ 2457.625729]  ? asm_exc_invalid_op+0x16/0x20
> [ 2457.632249]  ? rcu_tasks_trace_pregp_step+0x4a/0x50
> [ 2457.660010]  rcu_tasks_wait_gp+0x54/0x360
> [ 2457.677761]  ? _raw_spin_unlock_irqrestore+0x2b/0x60
> [ 2457.705658]  rcu_tasks_kthread+0x114/0x200
> [ 2457.712450]  ? wait_woken+0x70/0x70
> [ 2457.727283]  ? synchronize_rcu_tasks_rude+0x10/0x10
> [ 2457.746221]  kthread+0x130/0x160
> [ 2457.751487]  ? set_kthread_struct+0x40/0x40
> [ 2457.758178]  ret_from_fork+0x22/0x30
> [ 2457.763909]  </TASK>
> [ 2457.767546] irq event stamp: 29544441
> [ 2457.773344] hardirqs last  enabled at (29544451): [<ffffffffaace6cbd>] __up_console_sem+0x4d/0x60
> [ 2457.786967] hardirqs last disabled at (29544460): [<ffffffffaace6ca2>] __up_console_sem+0x32/0x60
> -------------------------------------
> 
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>

Nice!!!

One request, though.  If I am reading this correctly, if a console.log
file is filled with splats, then console.log.diags will replicate most
of console.log.  Could you please limit something, perhaps the number
of lines, the number of splats, or some such?

Just for context, my use case for the current setup is to run
kvm-find-errors.sh, which puts each console.log.diags/console.log pair
into my editor.  I copy an appropriate string from the console.log.diags,
and then paste that string to search for it in the corresponding
console.log file, which is what is edited next.

This script does the same with any build errors.

							Thanx, Paul

> ---
>  .../rcutorture/bin/console-badness.sh         | 24 ++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/rcutorture/bin/console-badness.sh b/tools/testing/selftests/rcutorture/bin/console-badness.sh
> index aad51e7c0183..d28efcd86b64 100755
> --- a/tools/testing/selftests/rcutorture/bin/console-badness.sh
> +++ b/tools/testing/selftests/rcutorture/bin/console-badness.sh
> @@ -9,10 +9,32 @@
>  # Copyright (C) 2020 Facebook, Inc.
>  #
>  # Authors: Paul E. McKenney <paulmck@...nel.org>
> +INPUT_DATA=$(< /dev/stdin)
>  
> -grep -E 'Badness|WARNING:|Warn|BUG|===========|BUG: KCSAN:|Call Trace:|Oops:|detected stalls on CPUs/tasks:|self-detected stall on CPU|Stall ended before state dump start|\?\?\? Writer stall state|rcu_.*kthread starved for|!!!' |
> +# Get the line numbers for all the grep matches
> +GREP_LINES="$(echo "$INPUT_DATA" |
> +grep -n -E 'Badness|WARNING:|Warn|BUG|===========|BUG: KCSAN:|Call Trace:|Oops:|detected stalls on CPUs/tasks:|self-detected stall on CPU|Stall ended before state dump start|\?\?\? Writer stall state|rcu_.*kthread starved for|!!!' |
>  grep -v 'ODEBUG: ' |
>  grep -v 'This means that this is a DEBUG kernel and it is' |
>  grep -v 'Warning: unable to open an initial console' |
>  grep -v 'Warning: Failed to add ttynull console. No stdin, stdout, and stderr.*the init process!' |
>  grep -v 'NOHZ tick-stop error: Non-RCU local softirq work is pending, handler'
> +)"
> +
> +# Exit if no grep matches
> +if [ ! -n "$GREP_LINES" ]; then exit 0; fi
> +
> +# Go through each line of GREP_LINES, extract the line number and then
> +# print from that line and 20 lines after that line. Do that for each
> +# grep match.
> +issue_num=1
> +while IFS= read -r line; do
> +    # Extract the line number from the line
> +    num=$(echo "$line" | awk -F: '{print $1}')
> +    # Print 20 lines after the matched line
> +    echo "Issue $issue_num:"
> +    issue_num="$(($issue_num + 1))"
> +    echo "$INPUT_DATA" | sed -n "${num},$(($num + 20))p"
> +    echo "-------------------------------------"
> +done <<< "$GREP_LINES"
> +
> -- 
> 2.42.0.rc2.253.gd59a3bf2b4-goog
>