From: Joerg Roedel <jroedel@suse.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>,
Andrew Morton <akpm@linux-foundation.org>,
Shile Zhang <shile.zhang@linux.alibaba.com>,
Andy Lutomirski <luto@amacapital.net>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Subject: Re: [RFC][PATCH] x86/mm: Sync all vmalloc mappings before text_poke()
Date: Wed, 29 Apr 2020 12:59:41 +0200 [thread overview]
Message-ID: <20200429105941.GQ30814@suse.de> (raw)
In-Reply-To: <20200429054857.66e8e333@oasis.local.home>
Hi Steven,
On Wed, Apr 29, 2020 at 05:48:57AM -0400, Steven Rostedt wrote:
> From: Steven Rostedt (VMware) <rostedt@goodmis.org>
>
> Tzvetomir was adding a feature to trace-cmd that would allow the user
> to specify filtering on process IDs within a tracing instance (or
> buffer). When he added this feature and tested it on tracing PIDs 1 and
> 2, it caused his kernel to hang.
>
> He sent me his code and I was able to reproduce the hang as well. I
> bisected it down to this commit 763802b53a42 ("x86/mm: split
> vmalloc_sync_all()"). It was 100% reproducible. With the commit it
> would hang, and reverting the commit, it would work.
>
> Adding a bunch of printk()s, I found where it locked up. It was after
> the recording was finished, and a write of "0" to
> tracefs/instance/foo/events/enable. And in the code, it was:
>
> (you may skip to the end of the chain)
>
> system_enable_write() {
> __ftrace_set_clr_event() {
> __ftrace_set_clr_event_nolock() {
> ftrace_event_enable_disable() {
> __ftrace_event_enable_disable() {
> call->class->reg() <trace_event_reg()> {
> trace_point_probe_unregister() {
> tracepoint_remove_func() {
> static_key_slow_dec() {
> __static_key_slow_dec() {
>
> <continued>
>
> __static_key_slow_dec_cpus_locked() {
> jump_label_update() {
> __jump_label_update()
> arch_jump_label_transform() {
> jump_label_transform() {
> __jump_label_transform() {
> text_poke_bp() {
> text_poke_bp_batch() {
> text_poke() {
> __text_poke() {
>
> <continued> (This is where you want to see)
>
> use_temporary_mm() {
> switch_mm_irqs_off() {
> load_new_mm_cr3() {
> write_cr3() <<--- Lock up!
I don't see how it could lock up in write_cr3(), at least on bare-metal.
What is the environment this happens, 32 or 64 bit, in a VM or
bare-metal?
I think it is more likely that your lockup is actually a page-fault
loop, where the #PF handler does not map the faulting address correctly.
But I have to look closer into how text_poke() works before I can say
more.
Btw, in case it happens on x86-64, does it also happen without
vmalloc-stacks?
Regards,
Joerg
next prev parent reply other threads:[~2020-04-29 10:59 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-29 9:48 [RFC][PATCH] x86/mm: Sync all vmalloc mappings before text_poke() Steven Rostedt
2020-04-29 10:59 ` Joerg Roedel [this message]
2020-04-29 12:28 ` Steven Rostedt
2020-04-29 14:07 ` Steven Rostedt
2020-04-29 14:10 ` Joerg Roedel
2020-04-29 14:32 ` Steven Rostedt
2020-04-29 15:44 ` Peter Zijlstra
2020-04-29 16:17 ` Joerg Roedel
2020-04-29 16:20 ` Joerg Roedel
2020-04-29 16:52 ` Steven Rostedt
2020-04-29 17:29 ` Mathieu Desnoyers
2020-04-29 18:51 ` Peter Zijlstra
2020-04-30 14:11 ` Joerg Roedel
2020-04-30 14:50 ` Joerg Roedel
2020-04-30 15:20 ` Mathieu Desnoyers
2020-04-30 16:16 ` Steven Rostedt
2020-04-30 16:18 ` Mathieu Desnoyers
2020-04-30 16:30 ` Steven Rostedt
2020-04-30 16:35 ` Mathieu Desnoyers
2020-04-30 15:23 ` Mathieu Desnoyers
2020-04-30 16:12 ` Steven Rostedt
2020-04-30 16:11 ` Steven Rostedt
2020-04-30 16:16 ` Mathieu Desnoyers
2020-04-30 16:25 ` Steven Rostedt
2020-04-30 19:14 ` Joerg Roedel
2020-05-01 1:13 ` Steven Rostedt
2020-05-01 2:26 ` Mathieu Desnoyers
2020-05-01 2:39 ` Steven Rostedt
2020-05-01 10:16 ` Joerg Roedel
2020-05-01 13:35 ` Mathieu Desnoyers
2020-05-04 15:12 ` [PATCH] percpu: Sync vmalloc mappings in pcpu_alloc() and free_percpu() Joerg Roedel
2020-05-04 15:28 ` Mathieu Desnoyers
2020-05-04 15:31 ` Joerg Roedel
2020-05-04 15:38 ` Mathieu Desnoyers
2020-05-04 15:51 ` Joerg Roedel
2020-05-04 17:04 ` Steven Rostedt
2020-05-04 17:40 ` Steven Rostedt
2020-05-04 18:38 ` Joerg Roedel
2020-05-04 19:10 ` Steven Rostedt
2020-05-05 12:31 ` [PATCH] tracing: Call vmalloc_sync_mappings() after alloc_percpu() Joerg Roedel
2020-05-06 15:17 ` Steven Rostedt
2020-05-08 14:42 ` Joerg Roedel
2020-05-04 20:25 ` [PATCH] percpu: Sync vmalloc mappings in pcpu_alloc() and free_percpu() Peter Zijlstra
2020-05-04 20:43 ` Steven Rostedt
2020-05-01 4:20 ` [RFC][PATCH] x86/mm: Sync all vmalloc mappings before text_poke() Steven Rostedt
2020-05-01 13:22 ` Mathieu Desnoyers
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