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Date: Wed, 8 Jan 2025 13:50:48 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <olsajiri@gmail.com>
Cc: Pu Lehui <pulehui@huaweicloud.com>, bpf@vger.kernel.org,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@fomichev.me>,
	Hao Luo <haoluo@google.com>, Jann Horn <jannh@google.com>,
	Pu Lehui <pulehui@huawei.com>
Subject: Re: [PATCH bpf-next v2] bpf: Move out synchronize_rcu_tasks_trace
 from mutex CS
Message-ID: <20250108125048.GG23315@noisy.programming.kicks-ass.net>
References: <20250104013946.1111785-1-pulehui@huaweicloud.com>
 <Z35gz9q8z7LBNssS@krava>
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In-Reply-To: <Z35gz9q8z7LBNssS@krava>

On Wed, Jan 08, 2025 at 12:26:07PM +0100, Jiri Olsa wrote:
> On Sat, Jan 04, 2025 at 01:39:46AM +0000, Pu Lehui wrote:
> > From: Pu Lehui <pulehui@huawei.com>
> > 
> > Commit ef1b808e3b7c ("bpf: Fix UAF via mismatching bpf_prog/attachment
> > RCU flavors") resolved a possible UAF issue in uprobes that attach
> > non-sleepable bpf prog by explicitly waiting for a tasks-trace-RCU grace
> > period. But, in the current implementation, synchronize_rcu_tasks_trace
> > is included within the mutex critical section, which increases the
> > length of the critical section and may affect performance. So let's move
> > out synchronize_rcu_tasks_trace from mutex CS.
> 
> lgtm, adding peter

Yeah, I don't immediately see anything funny there either. Carry on.