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>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [RFC][PATCH] x86/mm: Sync all vmalloc mappings before text_poke()
Date: Thu, 30 Apr 2020 21:14:34 +0200 [thread overview]
Message-ID: <20200430191434.GC8135@suse.de> (raw)
In-Reply-To: <20200430121136.6d7aeb22@gandalf.local.home>
On Thu, Apr 30, 2020 at 12:11:36PM -0400, Steven Rostedt wrote:
> bool trace_event_ignore_this_pid(struct trace_event_file *trace_file)
> {
> struct trace_array *tr = trace_file->tr;
> struct trace_array_cpu *data;
> struct trace_pid_list *no_pid_list;
> struct trace_pid_list *pid_list;
>
> pid_list = rcu_dereference_raw(tr->filtered_pids);
> no_pid_list = rcu_dereference_raw(tr->filtered_no_pids);
>
> if (!pid_list && !no_pid_list)
> return false;
>
> data = this_cpu_ptr(tr->array_buffer.data);
>
> return data->ignore_pid;
> }
>
> [...]
>
> tl;dr; It's not an issue with the vmalloc, it's an issue with per_cpu
> allocations!
Yes, looks like you are right, it faults on the return statement, so the
data-pointer seems not to be mapped. I looked at another instance:
The trapping instruction is:
movzbl 0x7c(%rax),%eax
Which is a pointer-dereference, with %rax=0xffffe8ffffccc870. The 'data'
pointer is allocated with alloc_percpu().
And alloc_percpu() calls down into pcpu_alloc(), which allocates new
percpu chunks using vmalloc() on x86. And there we are again in the
vmalloc area.
Regards,
Joerg
next prev parent reply other threads:[~2020-04-30 19:14 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
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 [this message]
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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