From: Andrew Morton <akpm@linux-foundation.org>
To: Chen Zhongjin <chenzhongjin@huawei.com>
Cc: <linux-kernel@vger.kernel.org>,
<linux-trace-kernel@vger.kernel.org>, <yangjihong1@huawei.com>,
<naveen.n.rao@linux.ibm.com>, <anil.s.keshavamurthy@intel.com>,
<davem@davemloft.net>, <paulmck@kernel.org>,
<mhiramat@kernel.org>, <tglx@linutronix.de>,
<peterz@infradead.org>, <pmladek@suse.com>,
<dianders@chromium.org>, <npiggin@gmail.com>,
<mpe@ellerman.id.au>, <jkl820.git@gmail.com>,
<juerg.haefliger@canonical.com>, <rick.p.edgecombe@intel.com>,
<eric.devolder@oracle.com>, <mic@digikod.net>
Subject: Re: [PATCH] kprobes: Use synchronize_rcu_tasks_rude in kprobe_optimizer
Date: Wed, 17 Jan 2024 12:31:33 -0800 [thread overview]
Message-ID: <20240117123133.2e40438936167e6a4aec8b16@linux-foundation.org> (raw)
In-Reply-To: <20240117061636.288412-1-chenzhongjin@huawei.com>
On Wed, 17 Jan 2024 06:16:36 +0000 Chen Zhongjin <chenzhongjin@huawei.com> wrote:
> There is a deadlock scenario in kprobe_optimizer():
>
> pid A pid B pid C
> kprobe_optimizer() do_exit() perf_kprobe_init()
> mutex_lock(&kprobe_mutex) exit_tasks_rcu_start() mutex_lock(&kprobe_mutex)
> synchronize_rcu_tasks() zap_pid_ns_processes() // waiting kprobe_mutex
> // waiting tasks_rcu_exit_srcu kernel_wait4()
> // waiting pid C exit
>
> To avoid this deadlock loop, use synchronize_rcu_tasks_rude() in kprobe_optimizer()
> rather than synchronize_rcu_tasks(). synchronize_rcu_tasks_rude() can also promise
> that all preempted tasks have scheduled, but it will not wait tasks_rcu_exit_srcu.
>
> Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Thanks. Should we backport this fix into earlier kernels? If so, are
we able to identify a suitable Fixes: target?
next prev parent reply other threads:[~2024-01-17 20:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-17 6:16 Chen Zhongjin
2024-01-17 20:31 ` Andrew Morton [this message]
2024-01-18 14:41 ` Paul E. McKenney
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