From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: rostedt <rostedt@goodmis.org>
Cc: Joerg Roedel <jroedel@suse.de>,
linux-kernel <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: Thu, 30 Apr 2020 12:18:22 -0400 (EDT) [thread overview]
Message-ID: <947455570.77870.1588263502669.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20200430121627.682061e2@gandalf.local.home>
----- On Apr 30, 2020, at 12:16 PM, rostedt rostedt@goodmis.org wrote:
> On Thu, 30 Apr 2020 11:20:15 -0400 (EDT)
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
>
>> > The right fix is to call vmalloc_sync_mappings() right after allocating
>> > tracing or perf buffers via v[zm]alloc().
>>
>> Either right after allocation, or right before making the vmalloc'd data
>> structure visible to the instrumentation. In the case of the pid filter,
>> that would be the rcu_assign_pointer() which publishes the new pid filter
>> table.
>>
>> As long as vmalloc_sync_mappings() is performed somewhere *between* allocation
>> and publishing the pointer for instrumentation, it's fine.
>>
>> I'll let Steven decide on which approach works best for him.
>
> As stated in the other email, I don't see it having anything to do with
> vmalloc, but with the per_cpu() allocation. I'll test this theory out by
> not even allocating the pid masks and touching the per cpu data at every
> event to see if it crashes.
As pointed out in my other email, per-cpu allocation uses vmalloc when
size > PAGE_SIZE.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2020-04-30 16:18 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 [this message]
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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