From: Thomas Gleixner <tglx@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Sam Sun <samsun1006219@gmail.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
syzkaller-bugs@googlegroups.com, peterz@infradead.org,
jpoimboe@kernel.org, jbaron@akamai.com, ardb@kernel.org,
mingo@redhat.com, Borislav Petkov <bp@alien8.de>,
dave.hansen@linux.intel.com, hpa@zytor.com,
xrivendell7@gmail.com,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tejun Heo <tj@kernel.org>
Subject: Re: [Linux kernel bug] WARNING in static_key_slow_inc_cpuslocked
Date: Sun, 09 Jun 2024 18:02:49 +0200 [thread overview]
Message-ID: <87le3exfx2.ffs@tglx> (raw)
In-Reply-To: <20240609102530.0a292b07@rorschach.local.home>
On Sun, Jun 09 2024 at 10:25, Steven Rostedt wrote:
> On Sun, 09 Jun 2024 16:06:05 +0200
> Thomas Gleixner <tglx@linutronix.de> wrote:
>> CPU 0 CPU 1
>>
>> kernfs_fop_write_iter() kernfs_fop_write_iter()
>> set_attr_rdpmc() set_attr_rdpmc()
>> arch_jump_label_transform_queue() arch_jump_label_transform_queue()
>> mutex_lock(text_mutex) mutex_lock(text_mutex)
>> __jump_label_patch()
>> text_poke_queue()
>> mutex_unlokc(text_mutex)
>> __jump_label_patch()
>>
>> CPU 1 sees the original text and not the expected because CPU 0 did not
>> yet invoke arch_jump_label_transform_apply().
>>
>> So clearly set_attr_rdpmc() lacks serialization, no?
>>
> Hmm, but should jump labels fail when that happens? Or should it catch
> it, and not cause a BUG?
Well the bug is there to detect inconsistency and that clearly works :)
But I clearly can't read, because the jump label operations are
serialized via jump_label_mutex. Hrm...
next prev parent reply other threads:[~2024-06-09 16:02 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-09 6:33 [Linux kernel bug] WARNING in static_key_slow_inc_cpuslocked Sam Sun
2024-06-09 13:04 ` Steven Rostedt
2024-06-09 14:06 ` Thomas Gleixner
2024-06-09 14:25 ` Steven Rostedt
2024-06-09 16:02 ` Thomas Gleixner [this message]
2024-06-09 16:56 ` Thomas Gleixner
2024-06-09 19:39 ` Thomas Gleixner
2024-06-10 6:46 ` Peter Zijlstra
2024-06-10 10:34 ` Thomas Gleixner
2024-06-10 12:46 ` [patch 0/4] perf/x86, jump_label: Cure serialization issues Thomas Gleixner
2024-06-10 12:46 ` [patch 1/4] perf/x86: Serialize set_attr_rdpmc() Thomas Gleixner
2024-06-17 15:47 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2024-06-10 12:46 ` [patch 2/4] jump_label: Fix concurrency issues in static_key_slow_dec() Thomas Gleixner
2024-06-10 17:57 ` Peter Zijlstra
2024-06-10 18:00 ` Thomas Gleixner
2024-06-17 15:47 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2024-06-10 12:46 ` [patch 3/4] jump_label: Clarify condition in static_key_fast_inc_not_disabled() Thomas Gleixner
2024-06-17 15:47 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2024-06-10 12:46 ` [patch 4/4] jump_label: Simplify and clarify static_key_fast_inc_cpus_locked() Thomas Gleixner
2024-06-12 13:57 ` Uros Bizjak
2024-06-17 15:47 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
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